ASP.NET Core Blazor-Dateiuploads

Benutzende von Autofac Inversion of Control (IoC)-Containern

Wenn Sie den Autofac IoC-Container (Inversion of Control) anstelle des integrierten ASP.NET Core-Abhängigkeitsinjektionscontainers verwenden, legen Sie DisableImplicitFromServicesParameters in den serverseitigen Circuit-Handler-Hub-Optionen auf true fest. Weitere Informationen finden Sie unter FileUpload: Es wurden innerhalb der vorgegebenen Zeit keine Daten empfangen (dotnet/aspnetcore #38842).

Bei serverseitigen oder clientseitigen Apps gibt es speziell für die Komponente InputFile keine Größenbeschränkung für das Lesen oder Hochladen von Dateien. Blazor auf der Clientseite liest jedoch die Bytes der Datei in einen einzelnen JavaScript-Arraypuffer, wenn die Daten von JavaScript nach C# gemarshallt werden. Dieser Vorgang ist auf 2 GB oder den verfügbaren Arbeitsspeicher des Geräts beschränkt. Große Dateiuploads (> 250 MB) können bei clientseitigen Uploads mit der InputFile-Komponente fehlschlagen. Weitere Informationen finden Sie in den folgenden Diskussionen:

Die maximale unterstützte Dateigröße für die InputFile-Komponente beträgt 2 GB. Darüber hinaus liest Blazor auf der Clientseite die Bytes der Datei in einen einzelnen JavaScript-Arraypuffer, wenn die Daten von JavaScript nach C# gemarshallt werden. Dieser Vorgang ist auf 2 GB oder den verfügbaren Arbeitsspeicher des Geräts beschränkt. Große Dateiuploads (> 250 MB) können bei clientseitigen Uploads mit der InputFile-Komponente fehlschlagen. Weitere Informationen finden Sie in den folgenden Diskussionen:

@page "/file-upload-1"
@using System 
@using System.IO
@using Microsoft.AspNetCore.Hosting
@inject ILogger<FileUpload1> Logger
@inject IWebHostEnvironment Environment

<PageTitle>File Upload 1</PageTitle>

<h1>File Upload Example 1</h1>

<p>
    <label>
        Max file size:
        <input type="number" @bind="maxFileSize" />
    </label>
</p>

<p>
    <label>
        Max allowed files:
        <input type="number" @bind="maxAllowedFiles" />
    </label>
</p>

<p>
    <label>
        Upload up to @maxAllowedFiles of up to @maxFileSize bytes:
        <InputFile OnChange="LoadFiles" multiple />
    </label>
</p>

@if (isLoading)
{
    <p>Uploading...</p>
}
else
{
    <ul>
        @foreach (var file in loadedFiles)
        {
            <li>
                <ul>
                    <li>Name: @file.Name</li>
                    <li>Last modified: @file.LastModified.ToString()</li>
                    <li>Size (bytes): @file.Size</li>
                    <li>Content type: @file.ContentType</li>
                </ul>
            </li>
        }
    </ul>
}

@code {
    private List<IBrowserFile> loadedFiles = new();
    private long maxFileSize = 1024 * 15;
    private int maxAllowedFiles = 3;
    private bool isLoading;

    private async Task LoadFiles(InputFileChangeEventArgs e)
    {
        isLoading = true;
        loadedFiles.Clear();

        foreach (var file in e.GetMultipleFiles(maxAllowedFiles))
        {
            try
            {
                var trustedFileName = Path.GetRandomFileName();
                var path = Path.Combine(Environment.ContentRootPath,
                    Environment.EnvironmentName, "unsafe_uploads",
                    trustedFileName);

                await using FileStream fs = new(path, FileMode.Create);
                await file.OpenReadStream(maxFileSize).CopyToAsync(fs);

                loadedFiles.Add(file);

                Logger.LogInformation(
                    "Unsafe Filename: {UnsafeFilename} File saved: {Filename}",
                    file.Name, trustedFileName);
            }
            catch (Exception ex)
            {
                Logger.LogError("File: {Filename} Error: {Error}", 
                    file.Name, ex.Message);
            }
        }

        isLoading = false;
    }
}

@page "/file-upload-1"
@using System 
@using System.IO
@using Microsoft.AspNetCore.Hosting
@using Microsoft.Extensions.Logging
@inject ILogger<FileUpload1> Logger
@inject IWebHostEnvironment Environment

<h3>Upload Files</h3>

<p>
    <label>
        Max file size:
        <input type="number" @bind="maxFileSize" />
    </label>
</p>

<p>
    <label>
        Max allowed files:
        <input type="number" @bind="maxAllowedFiles" />
    </label>
</p>

<p>
    <label>
        Upload up to @maxAllowedFiles of up to @maxFileSize bytes:
        <InputFile OnChange="LoadFiles" multiple />
    </label>
</p>

@if (isLoading)
{
    <p>Uploading...</p>
}
else
{
    <ul>
        @foreach (var file in loadedFiles)
        {
            <li>
                <ul>
                    <li>Name: @file.Name</li>
                    <li>Last modified: @file.LastModified.ToString()</li>
                    <li>Size (bytes): @file.Size</li>
                    <li>Content type: @file.ContentType</li>
                </ul>
            </li>
        }
    </ul>
}

@code {
    private List<IBrowserFile> loadedFiles = new();
    private long maxFileSize = 1024 * 15;
    private int maxAllowedFiles = 3;
    private bool isLoading;

    private async Task LoadFiles(InputFileChangeEventArgs e)
    {
        isLoading = true;
        loadedFiles.Clear();

        foreach (var file in e.GetMultipleFiles(maxAllowedFiles))
        {
            try
            {
                loadedFiles.Add(file);

                var trustedFileNameForFileStorage = Path.GetRandomFileName();
                var path = Path.Combine(Environment.ContentRootPath,
                        Environment.EnvironmentName, "unsafe_uploads",
                        trustedFileNameForFileStorage);

                await using FileStream fs = new(path, FileMode.Create);
                await file.OpenReadStream(maxFileSize).CopyToAsync(fs);
            }
            catch (Exception ex)
            {
                Logger.LogError("File: {Filename} Error: {Error}", 
                    file.Name, ex.Message);
            }
        }

        isLoading = false;
    }
}

@page "/file-upload-1"
@using System 
@using System.IO
@using Microsoft.AspNetCore.Hosting
@using Microsoft.Extensions.Logging
@inject ILogger<FileUpload1> Logger
@inject IWebHostEnvironment Environment

<h3>Upload Files</h3>

<p>
    <label>
        Max file size:
        <input type="number" @bind="maxFileSize" />
    </label>
</p>

<p>
    <label>
        Max allowed files:
        <input type="number" @bind="maxAllowedFiles" />
    </label>
</p>

<p>
    <label>
        Upload up to @maxAllowedFiles of up to @maxFileSize bytes:
        <InputFile OnChange="LoadFiles" multiple />
    </label>
</p>

@if (isLoading)
{
    <p>Uploading...</p>
}
else
{
    <ul>
        @foreach (var file in loadedFiles)
        {
            <li>
                <ul>
                    <li>Name: @file.Name</li>
                    <li>Last modified: @file.LastModified.ToString()</li>
                    <li>Size (bytes): @file.Size</li>
                    <li>Content type: @file.ContentType</li>
                </ul>
            </li>
        }
    </ul>
}

@code {
    private List<IBrowserFile> loadedFiles = new();
    private long maxFileSize = 1024 * 15;
    private int maxAllowedFiles = 3;
    private bool isLoading;

    private async Task LoadFiles(InputFileChangeEventArgs e)
    {
        isLoading = true;
        loadedFiles.Clear();

        foreach (var file in e.GetMultipleFiles(maxAllowedFiles))
        {
            try
            {
                loadedFiles.Add(file);

                var trustedFileNameForFileStorage = Path.GetRandomFileName();
                var path = Path.Combine(Environment.ContentRootPath,
                        Environment.EnvironmentName, "unsafe_uploads",
                        trustedFileNameForFileStorage);

                await using FileStream fs = new(path, FileMode.Create);
                await file.OpenReadStream(maxFileSize).CopyToAsync(fs);
            }
            catch (Exception ex)
            {
                Logger.LogError("File: {Filename} Error: {Error}", 
                    file.Name, ex.Message);
            }
        }

        isLoading = false;
    }
}

@page "/file-upload-1"
@using System 
@using System.IO
@using Microsoft.AspNetCore.Hosting
@using Microsoft.Extensions.Logging
@inject ILogger<FileUpload1> Logger
@inject IWebHostEnvironment Environment

<h3>Upload Files</h3>

<p>
    <label>
        Max file size:
        <input type="number" @bind="maxFileSize" />
    </label>
</p>

<p>
    <label>
        Max allowed files:
        <input type="number" @bind="maxAllowedFiles" />
    </label>
</p>

<p>
    <label>
        Upload up to @maxAllowedFiles of up to @maxFileSize bytes:
        <InputFile OnChange="LoadFiles" multiple />
    </label>
</p>

@if (isLoading)
{
    <p>Uploading...</p>
}
else
{
    <ul>
        @foreach (var file in loadedFiles)
        {
            <li>
                <ul>
                    <li>Name: @file.Name</li>
                    <li>Last modified: @file.LastModified.ToString()</li>
                    <li>Size (bytes): @file.Size</li>
                    <li>Content type: @file.ContentType</li>
                </ul>
            </li>
        }
    </ul>
}

@code {
    private List<IBrowserFile> loadedFiles = new();
    private long maxFileSize = 1024 * 15;
    private int maxAllowedFiles = 3;
    private bool isLoading;

    private async Task LoadFiles(InputFileChangeEventArgs e)
    {
        isLoading = true;
        loadedFiles.Clear();

        foreach (var file in e.GetMultipleFiles(maxAllowedFiles))
        {
            try
            {
                loadedFiles.Add(file);

                var trustedFileNameForFileStorage = Path.GetRandomFileName();
                var path = Path.Combine(Environment.ContentRootPath,
                        Environment.EnvironmentName, "unsafe_uploads",
                        trustedFileNameForFileStorage);

                await using FileStream fs = new(path, FileMode.Create);
                await file.OpenReadStream(maxFileSize).CopyToAsync(fs);
            }
            catch (Exception ex)
            {
                Logger.LogError("File: {Filename} Error: {Error}", 
                    file.Name, ex.Message);
            }
        }

        isLoading = false;
    }
}

@page "/file-upload-1"
@inject ILogger<FileUpload1> Logger

<PageTitle>File Upload 1</PageTitle>

<h1>File Upload Example 1</h1>

<p>
    <label>
        Max file size:
        <input type="number" @bind="maxFileSize" />
    </label>
</p>

<p>
    <label>
        Max allowed files:
        <input type="number" @bind="maxAllowedFiles" />
    </label>
</p>

<p>
    <label>
        Upload up to @maxAllowedFiles of up to @maxFileSize bytes:
        <InputFile OnChange="LoadFiles" multiple />
    </label>
</p>

@if (isLoading)
{
    <p>Uploading...</p>
}
else
{
    <ul>
        @foreach (var file in loadedFiles)
        {
            <li>
                <ul>
                    <li>Name: @file.Name</li>
                    <li>Last modified: @file.LastModified.ToString()</li>
                    <li>Size (bytes): @file.Size</li>
                    <li>Content type: @file.ContentType</li>
                </ul>
            </li>
        }
    </ul>
}

@code {
    private List<IBrowserFile> loadedFiles = new();
    private long maxFileSize = 1024 * 15;
    private int maxAllowedFiles = 3;
    private bool isLoading;

    private void LoadFiles(InputFileChangeEventArgs e)
    {
        isLoading = true;
        loadedFiles.Clear();

        foreach (var file in e.GetMultipleFiles(maxAllowedFiles))
        {
            try
            {
                loadedFiles.Add(file);
            }
            catch (Exception ex)
            {
                Logger.LogError("File: {FileName} Error: {Error}", 
                    file.Name, ex.Message);
            }
        }

        isLoading = false;
    }
}

@page "/file-upload-1"
@using Microsoft.Extensions.Logging
@inject ILogger<FileUpload1> Logger

<h3>Upload Files</h3>

<p>
    <label>
        Max file size:
        <input type="number" @bind="maxFileSize" />
    </label>
</p>

<p>
    <label>
        Max allowed files:
        <input type="number" @bind="maxAllowedFiles" />
    </label>
</p>

<p>
    <label>
        Upload up to @maxAllowedFiles of up to @maxFileSize bytes:
        <InputFile OnChange="LoadFiles" multiple />
    </label>
</p>

@if (isLoading)
{
    <p>Uploading...</p>
}
else
{
    <ul>
        @foreach (var file in loadedFiles)
        {
            <li>
                <ul>
                    <li>Name: @file.Name</li>
                    <li>Last modified: @file.LastModified.ToString()</li>
                    <li>Size (bytes): @file.Size</li>
                    <li>Content type: @file.ContentType</li>
                </ul>
            </li>
        }
    </ul>
}

@code {
    private List<IBrowserFile> loadedFiles = new();
    private long maxFileSize = 1024 * 15;
    private int maxAllowedFiles = 3;
    private bool isLoading;

    private void LoadFiles(InputFileChangeEventArgs e)
    {
        isLoading = true;
        loadedFiles.Clear();

        foreach (var file in e.GetMultipleFiles(maxAllowedFiles))
        {
            try
            {
                loadedFiles.Add(file);
            }
            catch (Exception ex)
            {
                Logger.LogError("File: {FileName} Error: {Error}", 
                    file.Name, ex.Message);
            }
        }

        isLoading = false;
    }
}

@page "/file-upload-1"
@using Microsoft.Extensions.Logging
@inject ILogger<FileUpload1> Logger

<h3>Upload Files</h3>

<p>
    <label>
        Max file size:
        <input type="number" @bind="maxFileSize" />
    </label>
</p>

<p>
    <label>
        Max allowed files:
        <input type="number" @bind="maxAllowedFiles" />
    </label>
</p>

<p>
    <label>
        Upload up to @maxAllowedFiles of up to @maxFileSize bytes:
        <InputFile OnChange="LoadFiles" multiple />
    </label>
</p>

@if (isLoading)
{
    <p>Uploading...</p>
}
else
{
    <ul>
        @foreach (var file in loadedFiles)
        {
            <li>
                <ul>
                    <li>Name: @file.Name</li>
                    <li>Last modified: @file.LastModified.ToString()</li>
                    <li>Size (bytes): @file.Size</li>
                    <li>Content type: @file.ContentType</li>
                </ul>
            </li>
        }
    </ul>
}

@code {
    private List<IBrowserFile> loadedFiles = new();
    private long maxFileSize = 1024 * 15;
    private int maxAllowedFiles = 3;
    private bool isLoading;

    private void LoadFiles(InputFileChangeEventArgs e)
    {
        isLoading = true;
        loadedFiles.Clear();

        foreach (var file in e.GetMultipleFiles(maxAllowedFiles))
        {
            try
            {
                loadedFiles.Add(file);
            }
            catch (Exception ex)
            {
                Logger.LogError("File: {Filename} Error: {Error}", 
                    file.Name, ex.Message);
            }
        }

        isLoading = false;
    }
}

@page "/file-upload-1"
@using Microsoft.Extensions.Logging
@inject ILogger<FileUpload1> Logger

<h3>Upload Files</h3>

<p>
    <label>
        Max file size:
        <input type="number" @bind="maxFileSize" />
    </label>
</p>

<p>
    <label>
        Max allowed files:
        <input type="number" @bind="maxAllowedFiles" />
    </label>
</p>

<p>
    <label>
        Upload up to @maxAllowedFiles of up to @maxFileSize bytes:
        <InputFile OnChange="LoadFiles" multiple />
    </label>
</p>

@if (isLoading)
{
    <p>Uploading...</p>
}
else
{
    <ul>
        @foreach (var file in loadedFiles)
        {
            <li>
                <ul>
                    <li>Name: @file.Name</li>
                    <li>Last modified: @file.LastModified.ToString()</li>
                    <li>Size (bytes): @file.Size</li>
                    <li>Content type: @file.ContentType</li>
                </ul>
            </li>
        }
    </ul>
}

@code {
    private List<IBrowserFile> loadedFiles = new();
    private long maxFileSize = 1024 * 15;
    private int maxAllowedFiles = 3;
    private bool isLoading;

    private void LoadFiles(InputFileChangeEventArgs e)
    {
        isLoading = true;
        loadedFiles.Clear();

        foreach (var file in e.GetMultipleFiles(maxAllowedFiles))
        {
            try
            {
                loadedFiles.Add(file);
            }
            catch (Exception ex)
            {
                Logger.LogError("File: {Filename} Error: {Error}", 
                    file.Name, ex.Message);
            }
        }

        isLoading = false;
    }
}

using Microsoft.AspNetCore.Components.Forms;
using System.Diagnostics.CodeAnalysis;

namespace BlazorSample;

internal sealed class LazyBrowserFileStream(IBrowserFile file, int maxAllowedSize) 
    : Stream
{
    private readonly IBrowserFile file = file;
    private readonly int maxAllowedSize = maxAllowedSize;
    private Stream? underlyingStream;
    private bool isDisposed;

    public override bool CanRead => true;

    public override bool CanSeek => false;

    public override bool CanWrite => false;

    public override long Length => file.Size;

    public override long Position
    {
        get => underlyingStream?.Position ?? 0;
        set => throw new NotSupportedException();
    }

    public override void Flush() => underlyingStream?.Flush();

    public override Task<int> ReadAsync(byte[] buffer, int offset, int count, 
        CancellationToken cancellationToken)
    {
        EnsureStreamIsOpen();

        return underlyingStream.ReadAsync(buffer, offset, count, cancellationToken);
    }

    public override ValueTask<int> ReadAsync(Memory<byte> buffer, 
        CancellationToken cancellationToken = default)
    {
        EnsureStreamIsOpen();
        return underlyingStream.ReadAsync(buffer, cancellationToken);
    }

    [MemberNotNull(nameof(underlyingStream))]
    private void EnsureStreamIsOpen() => 
        underlyingStream ??= file.OpenReadStream(maxAllowedSize);

    protected override void Dispose(bool disposing)
    {
        if (isDisposed)
        {
            return;
        }

        underlyingStream?.Dispose();
        isDisposed = true;

        base.Dispose(disposing);
    }

    public override int Read(byte[] buffer, int offset, int count)
        => throw new NotSupportedException();

    public override long Seek(long offset, SeekOrigin origin)
        => throw new NotSupportedException();

    public override void SetLength(long value)
        => throw new NotSupportedException();

    public override void Write(byte[] buffer, int offset, int count)
        => throw new NotSupportedException();
}

using Microsoft.AspNetCore.Components.Forms;
using System.Diagnostics.CodeAnalysis;

namespace BlazorSample;

internal sealed class LazyBrowserFileStream : Stream
{
    private readonly IBrowserFile file;
    private readonly int maxAllowedSize;
    private Stream? underlyingStream;
    private bool isDisposed;

    public override bool CanRead => true;

    public override bool CanSeek => false;

    public override bool CanWrite => false;

    public override long Length => file.Size;

    public override long Position
    {
        get => underlyingStream?.Position ?? 0;
        set => throw new NotSupportedException();
    }

    public LazyBrowserFileStream(IBrowserFile file, int maxAllowedSize)
    {
        this.file = file;
        this.maxAllowedSize = maxAllowedSize;
    }

    public override void Flush()
    {
        underlyingStream?.Flush();
    }

    public override Task<int> ReadAsync(byte[] buffer, int offset, int count, 
        CancellationToken cancellationToken)
    {
        EnsureStreamIsOpen();

        return underlyingStream.ReadAsync(buffer, offset, count, cancellationToken);
    }

    public override ValueTask<int> ReadAsync(Memory<byte> buffer, 
        CancellationToken cancellationToken = default)
    {
        EnsureStreamIsOpen();
        return underlyingStream.ReadAsync(buffer, cancellationToken);
    }

    [MemberNotNull(nameof(underlyingStream))]
    private void EnsureStreamIsOpen()
    {
        underlyingStream ??= file.OpenReadStream(maxAllowedSize);
    }

    protected override void Dispose(bool disposing)
    {
        if (isDisposed)
        {
            return;
        }

        underlyingStream?.Dispose();
        isDisposed = true;

        base.Dispose(disposing);
    }

    public override int Read(byte[] buffer, int offset, int count)
        => throw new NotSupportedException();

    public override long Seek(long offset, SeekOrigin origin)
        => throw new NotSupportedException();

    public override void SetLength(long value)
        => throw new NotSupportedException();

    public override void Write(byte[] buffer, int offset, int count)
        => throw new NotSupportedException();
}

using Microsoft.AspNetCore.Components.Forms;
using System.Diagnostics.CodeAnalysis;

namespace BlazorSample;

internal sealed class LazyBrowserFileStream : Stream
{
    private readonly IBrowserFile file;
    private readonly int maxAllowedSize;
    private Stream? underlyingStream;
    private bool isDisposed;

    public override bool CanRead => true;

    public override bool CanSeek => false;

    public override bool CanWrite => false;

    public override long Length => file.Size;

    public override long Position
    {
        get => underlyingStream?.Position ?? 0;
        set => throw new NotSupportedException();
    }

    public LazyBrowserFileStream(IBrowserFile file, int maxAllowedSize)
    {
        this.file = file;
        this.maxAllowedSize = maxAllowedSize;
    }

    public override void Flush()
    {
        underlyingStream?.Flush();
    }

    public override Task<int> ReadAsync(byte[] buffer, int offset, int count, 
        CancellationToken cancellationToken)
    {
        EnsureStreamIsOpen();

        return underlyingStream.ReadAsync(buffer, offset, count, cancellationToken);
    }

    public override ValueTask<int> ReadAsync(Memory<byte> buffer, 
        CancellationToken cancellationToken = default)
    {
        EnsureStreamIsOpen();
        return underlyingStream.ReadAsync(buffer, cancellationToken);
    }

    [MemberNotNull(nameof(underlyingStream))]
    private void EnsureStreamIsOpen()
    {
        underlyingStream ??= file.OpenReadStream(maxAllowedSize);
    }

    protected override void Dispose(bool disposing)
    {
        if (isDisposed)
        {
            return;
        }

        underlyingStream?.Dispose();
        isDisposed = true;

        base.Dispose(disposing);
    }

    public override int Read(byte[] buffer, int offset, int count)
        => throw new NotSupportedException();

    public override long Seek(long offset, SeekOrigin origin)
        => throw new NotSupportedException();

    public override void SetLength(long value)
        => throw new NotSupportedException();

    public override void Write(byte[] buffer, int offset, int count)
        => throw new NotSupportedException();
}

using System;
using System.Diagnostics.CodeAnalysis;
using System.IO;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Components.Forms;

namespace BlazorSample;

internal sealed class LazyBrowserFileStream : Stream
{
    private readonly IBrowserFile file;
    private readonly int maxAllowedSize;
    private Stream? underlyingStream;
    private bool isDisposed;

    public override bool CanRead => true;

    public override bool CanSeek => false;

    public override bool CanWrite => false;

    public override long Length => file.Size;

    public override long Position
    {
        get => underlyingStream?.Position ?? 0;
        set => throw new NotSupportedException();
    }

    public LazyBrowserFileStream(IBrowserFile file, int maxAllowedSize)
    {
        this.file = file;
        this.maxAllowedSize = maxAllowedSize;
    }

    public override void Flush()
    {
        underlyingStream?.Flush();
    }

    public override Task<int> ReadAsync(byte[] buffer, int offset, int count, 
        CancellationToken cancellationToken)
    {
        EnsureStreamIsOpen();

        return underlyingStream.ReadAsync(buffer, offset, count, cancellationToken);
    }

    public override ValueTask<int> ReadAsync(Memory<byte> buffer, 
        CancellationToken cancellationToken = default)
    {
        EnsureStreamIsOpen();
        return underlyingStream.ReadAsync(buffer, cancellationToken);
    }

    [MemberNotNull(nameof(underlyingStream))]
    private void EnsureStreamIsOpen()
    {
        underlyingStream ??= file.OpenReadStream(maxAllowedSize);
    }

    protected override void Dispose(bool disposing)
    {
        if (isDisposed)
        {
            return;
        }

        underlyingStream?.Dispose();
        isDisposed = true;

        base.Dispose(disposing);
    }

    public override int Read(byte[] buffer, int offset, int count)
        => throw new NotSupportedException();

    public override long Seek(long offset, SeekOrigin origin)
        => throw new NotSupportedException();

    public override void SetLength(long value)
        => throw new NotSupportedException();

    public override void Write(byte[] buffer, int offset, int count)
        => throw new NotSupportedException();
}

@page "/file-upload-2"
@using System.Net.Http.Headers
@using System.Text.Json
@inject IHttpClientFactory ClientFactory
@inject ILogger<FileUpload2> Logger

<PageTitle>File Upload 2</PageTitle>

<h1>File Upload Example 2</h1>

<p>
    This example requires a backend server API to function. For more information, 
    see the <em>Upload files to a server</em> section 
    of the <em>ASP.NET Core Blazor file uploads</em> article.
</p>

<p>
    <label>
        Upload up to @maxAllowedFiles files:
        <InputFile OnChange="OnInputFileChange" multiple />
    </label>
</p>

@if (files.Any())
{
    <div class="card">
        <div class="card-body">
            <ul>
                @foreach (var file in files)
                {
                    <li>
                        File: @file.Name
                        <br>
                        @if (FileUpload(uploadResults, file.Name, Logger,
                           out var result))
                        {
                            <span>
                                Stored File Name: @result.StoredFileName
                            </span>
                        }
                        else
                        {
                            <span>
                                There was an error uploading the file
                                (Error: @result.ErrorCode).
                            </span>
                        }
                    </li>
                }
            </ul>
        </div>
    </div>
}

@code {
    private List<File> files = new();
    private List<UploadResult> uploadResults = new();
    private int maxAllowedFiles = 3;
    private bool shouldRender;

    protected override bool ShouldRender() => shouldRender;

    private async Task OnInputFileChange(InputFileChangeEventArgs e)
    {
        shouldRender = false;
        int maxFileSize = 1024 * 15;
        var upload = false;

        using var content = new MultipartFormDataContent();

        foreach (var file in e.GetMultipleFiles(maxAllowedFiles))
        {
            if (uploadResults.SingleOrDefault(
                f => f.FileName == file.Name) is null)
            {
                try
                {
                    files.Add(new() { Name = file.Name });

                    var stream = new LazyBrowserFileStream(file, maxFileSize);
                    var fileContent = new StreamContent(stream);

                    fileContent.Headers.ContentType = 
                        new MediaTypeHeaderValue(file.ContentType);

                    content.Add(
                        content: fileContent,
                        name: "\"files\"",
                        fileName: file.Name);

                    upload = true;
                }
                catch (Exception ex)
                {
                    Logger.LogInformation(
                        "{FileName} not uploaded (Err: 6): {Message}", 
                        file.Name, ex.Message);

                    uploadResults.Add(
                        new()
                        {
                            FileName = file.Name, 
                            ErrorCode = 6, 
                            Uploaded = false
                        });
                }
            }
        }

        if (upload)
        {
            var client = ClientFactory.CreateClient();

            var response = 
                await client.PostAsync("https://localhost:5001/Filesave", 
                content);

            if (response.IsSuccessStatusCode)
            {
                var options = new JsonSerializerOptions
                {
                    PropertyNameCaseInsensitive = true,
                };

                using var responseStream =
                    await response.Content.ReadAsStreamAsync();

                var newUploadResults = await JsonSerializer
                    .DeserializeAsync<IList<UploadResult>>(responseStream, options);

                if (newUploadResults is not null)
                {
                    uploadResults = uploadResults.Concat(newUploadResults).ToList();
                }
            }
        }

        shouldRender = true;
    }

    private static bool FileUpload(IList<UploadResult> uploadResults,
        string? fileName, ILogger<FileUpload2> logger, out UploadResult result)
    {
        result = uploadResults.SingleOrDefault(f => f.FileName == fileName) ?? new();

        if (!result.Uploaded)
        {
            logger.LogInformation("{FileName} not uploaded (Err: 5)", fileName);
            result.ErrorCode = 5;
        }

        return result.Uploaded;
    }

    private class File
    {
        public string? Name { get; set; }
    }
}

@page "/file-upload-2"
@using System.Net.Http.Headers
@using System.Text.Json
@inject IHttpClientFactory ClientFactory
@inject ILogger<FileUpload2> Logger

<h1>File Upload Example 2</h1>

<p>
    This example requires a backend server API to function. For more information, 
    see the <em>Upload files to a server</em> section 
    of the <em>ASP.NET Core Blazor file uploads</em> article.
</p>

<p>
    <label>
        Upload up to @maxAllowedFiles files:
        <InputFile OnChange="OnInputFileChange" multiple />
    </label>
</p>

@if (files.Count > 0)
{
    <div class="card">
        <div class="card-body">
            <ul>
                @foreach (var file in files)
                {
                    <li>
                        File: @file.Name
                        <br>
                        @if (FileUpload(uploadResults, file.Name, Logger,
                           out var result))
                        {
                            <span>
                                Stored File Name: @result.StoredFileName
                            </span>
                        }
                        else
                        {
                            <span>
                                There was an error uploading the file
                                (Error: @result.ErrorCode).
                            </span>
                        }
                    </li>
                }
            </ul>
        </div>
    </div>
}

@code {
    private List<File> files = new();
    private List<UploadResult> uploadResults = new();
    private int maxAllowedFiles = 3;
    private bool shouldRender;

    protected override bool ShouldRender() => shouldRender;

    private async Task OnInputFileChange(InputFileChangeEventArgs e)
    {
        shouldRender = false;
        int maxFileSize = 1024 * 15;
        var upload = false;

        using var content = new MultipartFormDataContent();

        foreach (var file in e.GetMultipleFiles(maxAllowedFiles))
        {
            if (uploadResults.SingleOrDefault(
                f => f.FileName == file.Name) is null)
            {
                try
                {
                    files.Add(new() { Name = file.Name });

                    var stream = new LazyBrowserFileStream(file, maxFileSize);
                    var fileContent = new StreamContent(stream);
                    fileContent.Headers.ContentType = 
                        new MediaTypeHeaderValue(file.ContentType);

                    content.Add(
                        content: fileContent,
                        name: "\"files\"",
                        fileName: file.Name);

                    upload = true;
                }
                catch (Exception ex)
                {
                    Logger.LogInformation(
                        "{FileName} not uploaded (Err: 6): {Message}", 
                        file.Name, ex.Message);

                    uploadResults.Add(
                        new()
                        {
                            FileName = file.Name, 
                            ErrorCode = 6, 
                            Uploaded = false
                        });
                }
            }
        }

        if (upload)
        {
            var client = ClientFactory.CreateClient();

            var response = 
                await client.PostAsync("https://localhost:5001/Filesave", 
                content);

            if (response.IsSuccessStatusCode)
            {
                var options = new JsonSerializerOptions
                {
                    PropertyNameCaseInsensitive = true,
                };

                using var responseStream =
                    await response.Content.ReadAsStreamAsync();

                var newUploadResults = await JsonSerializer
                    .DeserializeAsync<IList<UploadResult>>(responseStream, options);

                if (newUploadResults is not null)
                {
                    uploadResults = uploadResults.Concat(newUploadResults).ToList();
                }
            }
        }

        shouldRender = true;
    }

    private static bool FileUpload(IList<UploadResult> uploadResults,
        string? fileName, ILogger<FileUpload2> logger, out UploadResult result)
    {
        result = uploadResults.SingleOrDefault(f => f.FileName == fileName) ?? new();

        if (!result.Uploaded)
        {
            logger.LogInformation("{FileName} not uploaded (Err: 5)", fileName);
            result.ErrorCode = 5;
        }

        return result.Uploaded;
    }

    private class File
    {
        public string? Name { get; set; }
    }
}

@page "/file-upload-2"
@using System.Net.Http.Headers
@using System.Text.Json
@inject IHttpClientFactory ClientFactory
@inject ILogger<FileUpload2> Logger

<h1>File Upload Example 2</h1>

<p>
    This example requires a backend server API to function. For more information, 
    see the <em>Upload files to a server</em> section 
    of the <em>ASP.NET Core Blazor file uploads</em> article.
</p>

<p>
    <label>
        Upload up to @maxAllowedFiles files:
        <InputFile OnChange="OnInputFileChange" multiple />
    </label>
</p>

@if (files.Count > 0)
{
    <div class="card">
        <div class="card-body">
            <ul>
                @foreach (var file in files)
                {
                    <li>
                        File: @file.Name
                        <br>
                        @if (FileUpload(uploadResults, file.Name, Logger,
                           out var result))
                        {
                            <span>
                                Stored File Name: @result.StoredFileName
                            </span>
                        }
                        else
                        {
                            <span>
                                There was an error uploading the file
                                (Error: @result.ErrorCode).
                            </span>
                        }
                    </li>
                }
            </ul>
        </div>
    </div>
}

@code {
    private List<File> files = new();
    private List<UploadResult> uploadResults = new();
    private int maxAllowedFiles = 3;
    private bool shouldRender;

    protected override bool ShouldRender() => shouldRender;

    private async Task OnInputFileChange(InputFileChangeEventArgs e)
    {
        shouldRender = false;
        int maxFileSize = 1024 * 15;
        var upload = false;

        using var content = new MultipartFormDataContent();

        foreach (var file in e.GetMultipleFiles(maxAllowedFiles))
        {
            if (uploadResults.SingleOrDefault(
                f => f.FileName == file.Name) is null)
            {
                try
                {
                    files.Add(new() { Name = file.Name });

                    var stream = new LazyBrowserFileStream(file, maxFileSize);
                    var fileContent = new StreamContent(stream);
                    fileContent.Headers.ContentType = 
                        new MediaTypeHeaderValue(file.ContentType);

                    content.Add(
                        content: fileContent,
                        name: "\"files\"",
                        fileName: file.Name);

                    upload = true;
                }
                catch (Exception ex)
                {
                    Logger.LogInformation(
                        "{FileName} not uploaded (Err: 6): {Message}", 
                        file.Name, ex.Message);

                    uploadResults.Add(
                        new()
                        {
                            FileName = file.Name, 
                            ErrorCode = 6, 
                            Uploaded = false
                        });
                }
            }
        }

        if (upload)
        {
            var client = ClientFactory.CreateClient();

            var response = 
                await client.PostAsync("https://localhost:5001/Filesave", 
                content);

            if (response.IsSuccessStatusCode)
            {
                var options = new JsonSerializerOptions
                {
                    PropertyNameCaseInsensitive = true,
                };

                using var responseStream =
                    await response.Content.ReadAsStreamAsync();

                var newUploadResults = await JsonSerializer
                    .DeserializeAsync<IList<UploadResult>>(responseStream, options);

                if (newUploadResults is not null)
                {
                    uploadResults = uploadResults.Concat(newUploadResults).ToList();
                }
            }
        }

        shouldRender = true;
    }

    private static bool FileUpload(IList<UploadResult> uploadResults,
        string? fileName, ILogger<FileUpload2> logger, out UploadResult result)
    {
        result = uploadResults.SingleOrDefault(f => f.FileName == fileName) ?? new();

        if (!result.Uploaded)
        {
            logger.LogInformation("{FileName} not uploaded (Err: 5)", fileName);
            result.ErrorCode = 5;
        }

        return result.Uploaded;
    }

    private class File
    {
        public string? Name { get; set; }
    }
}

@page "/file-upload-2"
@using System.Net.Http.Headers
@using System.Text.Json
@using Microsoft.Extensions.Logging
@inject IHttpClientFactory ClientFactory
@inject ILogger<FileUpload2> Logger

<h1>File Upload Example 2</h1>

<p>
    This example requires a backend server API to function. For more information, 
    see the <em>Upload files to a server</em> section 
    of the <em>ASP.NET Core Blazor file uploads</em> article.
</p>

<p>
    <label>
        Upload up to @maxAllowedFiles files:
        <InputFile OnChange="OnInputFileChange" multiple />
    </label>
</p>

@if (files.Count > 0)
{
    <div class="card">
        <div class="card-body">
            <ul>
                @foreach (var file in files)
                {
                    <li>
                        File: @file.Name
                        <br>
                        @if (FileUpload(uploadResults, file.Name, Logger,
                           out var result))
                        {
                            <span>
                                Stored File Name: @result.StoredFileName
                            </span>
                        }
                        else
                        {
                            <span>
                                There was an error uploading the file
                                (Error: @result.ErrorCode).
                            </span>
                        }
                    </li>
                }
            </ul>
        </div>
    </div>
}

@code {
    private List<File> files = new();
    private List<UploadResult> uploadResults = new();
    private int maxAllowedFiles = 3;
    private bool shouldRender;

    protected override bool ShouldRender() => shouldRender;

    private async Task OnInputFileChange(InputFileChangeEventArgs e)
    {
        shouldRender = false;
        int maxFileSize = 1024 * 15;
        var upload = false;

        using var content = new MultipartFormDataContent();

        foreach (var file in e.GetMultipleFiles(maxAllowedFiles))
        {
            if (uploadResults.SingleOrDefault(
                f => f.FileName == file.Name) is null)
            {
                try
                {
                    files.Add(new() { Name = file.Name });

                    var stream = new LazyBrowserFileStream(file, maxFileSize);
                    var fileContent = new StreamContent(stream);
                    fileContent.Headers.ContentType = 
                        new MediaTypeHeaderValue(file.ContentType);

                    content.Add(
                        content: fileContent,
                        name: "\"files\"",
                        fileName: file.Name);

                    upload = true;
                }
                catch (Exception ex)
                {
                    Logger.LogInformation(
                        "{FileName} not uploaded (Err: 6): {Message}", 
                        file.Name, ex.Message);

                    uploadResults.Add(
                        new()
                        {
                            FileName = file.Name, 
                            ErrorCode = 6, 
                            Uploaded = false
                        });
                }
            }
        }

        if (upload)
        {
            var client = ClientFactory.CreateClient();

            var response = 
                await client.PostAsync("https://localhost:5001/Filesave", 
                content);

            if (response.IsSuccessStatusCode)
            {
                var options = new JsonSerializerOptions
                {
                    PropertyNameCaseInsensitive = true,
                };

                using var responseStream =
                    await response.Content.ReadAsStreamAsync();

                var newUploadResults = await JsonSerializer
                    .DeserializeAsync<IList<UploadResult>>(responseStream, options);

                if (newUploadResults is not null)
                {
                    uploadResults = uploadResults.Concat(newUploadResults).ToList();
                }
            }
        }

        shouldRender = true;
    }

    private static bool FileUpload(IList<UploadResult> uploadResults,
        string fileName, ILogger<FileUpload2> logger, out UploadResult result)
    {
        result = uploadResults.SingleOrDefault(f => f.FileName == fileName) ?? new();

        if (!result.Uploaded)
        {
            logger.LogInformation("{FileName} not uploaded (Err: 5)", fileName);
            result.ErrorCode = 5;
        }

        return result.Uploaded;
    }

    private class File
    {
        public string Name { get; set; }
    }
}

Wenn die Komponente das Hochladen von Dateien auf jeweils eine einzelne Datei beschränkt oder wenn die Komponente nur interaktives clientseitiges Rendering (CSR, InteractiveWebAssembly) übernimmt, kann die Komponente die Verwendung von LazyBrowserFileStream vermeiden und Stream verwenden. Im Folgenden werden die Änderungen für die FileUpload2 Komponente dargestellt:

- var stream = new LazyBrowserFileStream(file, maxFileSize);
- var fileContent = new StreamContent(stream);
+ var fileContent = new StreamContent(file.OpenReadStream(maxFileSize));

Entfernen Sie die LazyBrowserFileStream Klasse (LazyBrowserFileStream.cs), da sie nicht verwendet wird.

Wenn die Komponente das Hochladen von Dateien auf jeweils eine einzelne Datei beschränkt, kann die Komponente die Verwendung von LazyBrowserFileStream vermeiden und Stream verwenden. Im Folgenden werden die Änderungen für die FileUpload2 Komponente dargestellt:

- var stream = new LazyBrowserFileStream(file, maxFileSize);
- var fileContent = new StreamContent(stream);
+ var fileContent = new StreamContent(file.OpenReadStream(maxFileSize));

Entfernen Sie die LazyBrowserFileStream Klasse (LazyBrowserFileStream.cs), da sie nicht verwendet wird.

Im Blazor Web App-Hauptprojekt fügen Sie IHttpClientFactory und die zugehörigen Dienste in die Program-Datei des Projekts ein:

builder.Services.AddHttpClient();

Die HttpClient-Dienste müssen dem Hauptprojekt hinzugefügt werden, da die clientseitige Komponente auf dem Server vorab gerendert wird. Wenn Sie das Vorabrendering für die folgende Komponente deaktivieren, müssen Sie die HttpClient-Dienste in der Haupt-App nicht bereitstellen und die vorangehende Zeile nicht zum Hauptprojekt hinzufügen.

Weitere Informationen zum Hinzufügen von HttpClient-Diensten zu einer ASP.NET Core-App finden Sie unter Übermitteln von HTTP-Anforderungen mithilfe von IHttpClientFactory in ASP.NET Core.

Das Client-Projekt (.Client) einer Blazor Web App muss auch einen HttpClient für HTTP-POST-Anfragen an einen Back-End-Web-API-Controller registrieren. Überprüfen Sie Folgendes in der Datei Program des Clientprojekts, oder fügen Sie es hinzu:

builder.Services.AddScoped(sp => 
    new HttpClient { BaseAddress = new Uri(builder.HostEnvironment.BaseAddress) });

Im vorherigen Beispiel wird die Basisadresse mit builder.HostEnvironment.BaseAddress (IWebAssemblyHostEnvironment.BaseAddress) festgelegt, wodurch die Basisadresse für die App abgerufen und in der Regel vom href-Wert des <base>-Tags auf der Hostseite abgeleitet wird. Wenn Sie eine externe Web-API aufrufen, legen Sie den URI auf die Basisadresse der Web-API fest.

Geben Sie das Attribut Interaktiver WebAssembly-Rendermodus oben in der folgenden Komponente in einem Blazor Web App an:

@rendermode InteractiveWebAssembly

@page "/file-upload-2"
@using System.Linq
@using System.Net.Http.Headers
@inject HttpClient Http
@inject ILogger<FileUpload2> Logger

<PageTitle>File Upload 2</PageTitle>

<h1>File Upload Example 2</h1>

<p>
    <label>
        Upload up to @maxAllowedFiles files:
        <InputFile OnChange="OnInputFileChange" multiple />
    </label>
</p>

@if (files.Count > 0)
{
    <div class="card">
        <div class="card-body">
            <ul>
                @foreach (var file in files)
                {
                    <li>
                        File: @file.Name
                        <br>
                        @if (FileUpload(uploadResults, file.Name, Logger,
                           out var result))
                        {
                            <span>
                                Stored File Name: @result.StoredFileName
                            </span>
                        }
                        else
                        {
                            <span>
                                There was an error uploading the file
                                (Error: @result.ErrorCode).
                            </span>
                        }
                    </li>
                }
            </ul>
        </div>
    </div>
}

@code {
    private List<File> files = new();
    private List<UploadResult> uploadResults = new();
    private int maxAllowedFiles = 3;
    private bool shouldRender;

    protected override bool ShouldRender() => shouldRender;

    private async Task OnInputFileChange(InputFileChangeEventArgs e)
    {
        shouldRender = false;
        long maxFileSize = 1024 * 15;
        var upload = false;

        using var content = new MultipartFormDataContent();

        foreach (var file in e.GetMultipleFiles(maxAllowedFiles))
        {
            if (uploadResults.SingleOrDefault(
                f => f.FileName == file.Name) is null)
            {
                try
                {
                    files.Add(new() { Name = file.Name });

                    var fileContent = new StreamContent(file.OpenReadStream(maxFileSize));

                    fileContent.Headers.ContentType = 
                        new MediaTypeHeaderValue(file.ContentType);

                    content.Add(
                        content: fileContent,
                        name: "\"files\"",
                        fileName: file.Name);

                    upload = true;
                }
                catch (Exception ex)
                {
                    Logger.LogInformation(
                        "{FileName} not uploaded (Err: 6): {Message}", 
                        file.Name, ex.Message);

                    uploadResults.Add(
                        new()
                        {
                            FileName = file.Name, 
                            ErrorCode = 6, 
                            Uploaded = false
                        });
                }
            }
        }

        if (upload)
        {
            var response = await Http.PostAsync("/Filesave", content);

            var newUploadResults = await response.Content
                .ReadFromJsonAsync<IList<UploadResult>>();

            if (newUploadResults is not null)
            {
                uploadResults = uploadResults.Concat(newUploadResults).ToList();
            }
        }

        shouldRender = true;
    }

    private static bool FileUpload(IList<UploadResult> uploadResults,
        string? fileName, ILogger<FileUpload2> logger, out UploadResult result)
    {
        result = uploadResults.SingleOrDefault(f => f.FileName == fileName) ?? new();

        if (!result.Uploaded)
        {
            logger.LogInformation("{FileName} not uploaded (Err: 5)", fileName);
            result.ErrorCode = 5;
        }

        return result.Uploaded;
    }

    private class File
    {
        public string? Name { get; set; }
    }
}

@page "/file-upload-2"
@using System.Linq
@using System.Net.Http.Headers
@using Microsoft.Extensions.Logging
@inject HttpClient Http
@inject ILogger<FileUpload2> Logger

<h1>Upload Files</h1>

<p>
    <label>
        Upload up to @maxAllowedFiles files:
        <InputFile OnChange="OnInputFileChange" multiple />
    </label>
</p>

@if (files.Count > 0)
{
    <div class="card">
        <div class="card-body">
            <ul>
                @foreach (var file in files)
                {
                    <li>
                        File: @file.Name
                        <br>
                        @if (FileUpload(uploadResults, file.Name, Logger,
                           out var result))
                        {
                            <span>
                                Stored File Name: @result.StoredFileName
                            </span>
                        }
                        else
                        {
                            <span>
                                There was an error uploading the file
                                (Error: @result.ErrorCode).
                            </span>
                        }
                    </li>
                }
            </ul>
        </div>
    </div>
}

@code {
    private List<File> files = new();
    private List<UploadResult> uploadResults = new();
    private int maxAllowedFiles = 3;
    private bool shouldRender;

    protected override bool ShouldRender() => shouldRender;

    private async Task OnInputFileChange(InputFileChangeEventArgs e)
    {
        shouldRender = false;
        long maxFileSize = 1024 * 15;
        var upload = false;

        using var content = new MultipartFormDataContent();

        foreach (var file in e.GetMultipleFiles(maxAllowedFiles))
        {
            if (uploadResults.SingleOrDefault(
                f => f.FileName == file.Name) is null)
            {
                try
                {
                    files.Add(new() { Name = file.Name });

                    var fileContent = new StreamContent(file.OpenReadStream(maxFileSize));

                    fileContent.Headers.ContentType = 
                        new MediaTypeHeaderValue(file.ContentType);

                    content.Add(
                        content: fileContent,
                        name: "\"files\"",
                        fileName: file.Name);

                    upload = true;
                }
                catch (Exception ex)
                {
                    Logger.LogInformation(
                        "{FileName} not uploaded (Err: 6): {Message}", 
                        file.Name, ex.Message);

                    uploadResults.Add(
                        new()
                        {
                            FileName = file.Name, 
                            ErrorCode = 6, 
                            Uploaded = false
                        });
                }
            }
        }

        if (upload)
        {
            var response = await Http.PostAsync("/Filesave", content);

            var newUploadResults = await response.Content
                .ReadFromJsonAsync<IList<UploadResult>>();

            if (newUploadResults is not null)
            {
                uploadResults = uploadResults.Concat(newUploadResults).ToList();
            }
        }

        shouldRender = true;
    }

    private static bool FileUpload(IList<UploadResult> uploadResults,
        string? fileName, ILogger<FileUpload2> logger, out UploadResult result)
    {
        result = uploadResults.SingleOrDefault(f => f.FileName == fileName) ?? new();

        if (!result.Uploaded)
        {
            logger.LogInformation("{FileName} not uploaded (Err: 5)", fileName);
            result.ErrorCode = 5;
        }

        return result.Uploaded;
    }

    private class File
    {
        public string? Name { get; set; }
    }
}

@page "/file-upload-2"
@using System.Linq
@using System.Net.Http.Headers
@using Microsoft.Extensions.Logging
@inject HttpClient Http
@inject ILogger<FileUpload2> Logger

<h1>Upload Files</h1>

<p>
    <label>
        Upload up to @maxAllowedFiles files:
        <InputFile OnChange="OnInputFileChange" multiple />
    </label>
</p>

@if (files.Count > 0)
{
    <div class="card">
        <div class="card-body">
            <ul>
                @foreach (var file in files)
                {
                    <li>
                        File: @file.Name
                        <br>
                        @if (FileUpload(uploadResults, file.Name, Logger,
                           out var result))
                        {
                            <span>
                                Stored File Name: @result.StoredFileName
                            </span>
                        }
                        else
                        {
                            <span>
                                There was an error uploading the file
                                (Error: @result.ErrorCode).
                            </span>
                        }
                    </li>
                }
            </ul>
        </div>
    </div>
}

@code {
    private List<File> files = new();
    private List<UploadResult> uploadResults = new();
    private int maxAllowedFiles = 3;
    private bool shouldRender;

    protected override bool ShouldRender() => shouldRender;

    private async Task OnInputFileChange(InputFileChangeEventArgs e)
    {
        shouldRender = false;
        long maxFileSize = 1024 * 15;
        var upload = false;

        using var content = new MultipartFormDataContent();

        foreach (var file in e.GetMultipleFiles(maxAllowedFiles))
        {
            if (uploadResults.SingleOrDefault(
                f => f.FileName == file.Name) is null)
            {
                try
                {
                    files.Add(new() { Name = file.Name });

                    var fileContent = new StreamContent(file.OpenReadStream(maxFileSize));

                    fileContent.Headers.ContentType = 
                        new MediaTypeHeaderValue(file.ContentType);

                    content.Add(
                        content: fileContent,
                        name: "\"files\"",
                        fileName: file.Name);

                    upload = true;
                }
                catch (Exception ex)
                {
                    Logger.LogInformation(
                        "{FileName} not uploaded (Err: 6): {Message}", 
                        file.Name, ex.Message);

                    uploadResults.Add(
                        new()
                        {
                            FileName = file.Name, 
                            ErrorCode = 6, 
                            Uploaded = false
                        });
                }
            }
        }

        if (upload)
        {
            var response = await Http.PostAsync("/Filesave", content);

            var newUploadResults = await response.Content
                .ReadFromJsonAsync<IList<UploadResult>>();

            if (newUploadResults is not null)
            {
                uploadResults = uploadResults.Concat(newUploadResults).ToList();
            }
        }

        shouldRender = true;
    }

    private static bool FileUpload(IList<UploadResult> uploadResults,
        string? fileName, ILogger<FileUpload2> logger, out UploadResult result)
    {
        result = uploadResults.SingleOrDefault(f => f.FileName == fileName) ?? new();

        if (!result.Uploaded)
        {
            logger.LogInformation("{FileName} not uploaded (Err: 5)", fileName);
            result.ErrorCode = 5;
        }

        return result.Uploaded;
    }

    private class File
    {
        public string? Name { get; set; }
    }
}

@page "/file-upload-2"
@using System.Linq
@using System.Net.Http.Headers
@using Microsoft.Extensions.Logging
@inject HttpClient Http
@inject ILogger<FileUpload2> Logger

<h1>Upload Files</h1>

<p>
    <label>
        Upload up to @maxAllowedFiles files:
        <InputFile OnChange="OnInputFileChange" multiple />
    </label>
</p>

@if (files.Count > 0)
{
    <div class="card">
        <div class="card-body">
            <ul>
                @foreach (var file in files)
                {
                    <li>
                        File: @file.Name
                        <br>
                        @if (FileUpload(uploadResults, file.Name, Logger,
                           out var result))
                        {
                            <span>
                                Stored File Name: @result.StoredFileName
                            </span>
                        }
                        else
                        {
                            <span>
                                There was an error uploading the file
                                (Error: @result.ErrorCode).
                            </span>
                        }
                    </li>
                }
            </ul>
        </div>
    </div>
}

@code {
    private List<File> files = new();
    private List<UploadResult> uploadResults = new();
    private int maxAllowedFiles = 3;
    private bool shouldRender;

    protected override bool ShouldRender() => shouldRender;

    private async Task OnInputFileChange(InputFileChangeEventArgs e)
    {
        shouldRender = false;
        long maxFileSize = 1024 * 15;
        var upload = false;

        using var content = new MultipartFormDataContent();

        foreach (var file in e.GetMultipleFiles(maxAllowedFiles))
        {
            if (uploadResults.SingleOrDefault(
                f => f.FileName == file.Name) is null)
            {
                try
                {
                    files.Add(new() { Name = file.Name });

                    var fileContent = new StreamContent(file.OpenReadStream(maxFileSize));

                    fileContent.Headers.ContentType = 
                        new MediaTypeHeaderValue(file.ContentType);

                    content.Add(
                        content: fileContent,
                        name: "\"files\"",
                        fileName: file.Name);

                    upload = true;
                }
                catch (Exception ex)
                {
                    Logger.LogInformation(
                        "{FileName} not uploaded (Err: 6): {Message}", 
                        file.Name, ex.Message);

                    uploadResults.Add(
                        new()
                        {
                            FileName = file.Name, 
                            ErrorCode = 6, 
                            Uploaded = false
                        });
                }
            }
        }

        if (upload)
        {
            var response = await Http.PostAsync("/Filesave", content);

            var newUploadResults = await response.Content
                .ReadFromJsonAsync<IList<UploadResult>>();

            uploadResults = uploadResults.Concat(newUploadResults).ToList();
        }

        shouldRender = true;
    }

    private static bool FileUpload(IList<UploadResult> uploadResults,
        string fileName, ILogger<FileUpload2> logger, out UploadResult result)
    {
        result = uploadResults.SingleOrDefault(f => f.FileName == fileName);

        if (result is null)
        {
            logger.LogInformation("{FileName} not uploaded (Err: 5)", fileName);
            result = new();
            result.ErrorCode = 5;
        }

        return result.Uploaded;
    }

    private class File
    {
        public string Name { get; set; }
    }
}

@page "/file-upload-3"
@inject ILogger<FileUpload3> Logger
@inject IWebHostEnvironment Environment

<PageTitle>File Upload 3</PageTitle>

<h1>File Upload Example 3</h1>

<p>
    <label>
        Max file size:
        <input type="number" @bind="maxFileSize" />
    </label>
</p>

<p>
    <label>
        Max allowed files:
        <input type="number" @bind="maxAllowedFiles" />
    </label>
</p>

<p>
    <label>
        Upload up to @maxAllowedFiles of up to @maxFileSize bytes:
        <InputFile OnChange="LoadFiles" multiple />
    </label>
</p>

@if (isLoading)
{
    <p>Progress: @string.Format("{0:P0}", progressPercent)</p>
}
else
{
    <ul>
        @foreach (var file in loadedFiles)
        {
            <li>
                <ul>
                    <li>Name: @file.Name</li>
                    <li>Last modified: @file.LastModified.ToString()</li>
                    <li>Size (bytes): @file.Size</li>
                    <li>Content type: @file.ContentType</li>
                </ul>
            </li>
        }
    </ul>
}

@code {
    private List<IBrowserFile> loadedFiles = new();
    private long maxFileSize = 1024 * 15;
    private int maxAllowedFiles = 3;
    private bool isLoading;
    private decimal progressPercent;

    private async Task LoadFiles(InputFileChangeEventArgs e)
    {
        isLoading = true;
        loadedFiles.Clear();
        progressPercent = 0;

        foreach (var file in e.GetMultipleFiles(maxAllowedFiles))
        {
            try
            {
                var trustedFileName = Path.GetRandomFileName();
                var path = Path.Combine(Environment.ContentRootPath,
                    Environment.EnvironmentName, "unsafe_uploads", trustedFileName);

                await using FileStream writeStream = new(path, FileMode.Create);
                using var readStream = file.OpenReadStream(maxFileSize);
                var bytesRead = 0;
                var totalRead = 0;
                var buffer = new byte[1024 * 10];

                while ((bytesRead = await readStream.ReadAsync(buffer)) != 0)
                {
                    totalRead += bytesRead;
                    await writeStream.WriteAsync(buffer, 0, bytesRead);
                    progressPercent = Decimal.Divide(totalRead, file.Size);
                    StateHasChanged();
                }

                loadedFiles.Add(file);

                Logger.LogInformation(
                    "Unsafe Filename: {UnsafeFilename} File saved: {Filename}",
                    file.Name, trustedFileName);
            }
            catch (Exception ex)
            {
                Logger.LogError("File: {FileName} Error: {Error}", 
                    file.Name, ex.Message);
            }
        }

        isLoading = false;
    }
}

@page "/file-upload-3"
@using System 
@using System.IO
@using Microsoft.AspNetCore.Hosting
@using Microsoft.Extensions.Logging
@inject ILogger<FileUpload3> Logger
@inject IWebHostEnvironment Environment

<h3>Upload Files</h3>

<p>
    <label>
        Max file size:
        <input type="number" @bind="maxFileSize" />
    </label>
</p>

<p>
    <label>
        Max allowed files:
        <input type="number" @bind="maxAllowedFiles" />
    </label>
</p>

<p>
    <label>
        Upload up to @maxAllowedFiles of up to @maxFileSize bytes:
        <InputFile OnChange="LoadFiles" multiple />
    </label>
</p>

@if (isLoading)
{
    <p>Progress: @string.Format("{0:P0}", progressPercent)</p>
}
else
{
    <ul>
        @foreach (var file in loadedFiles)
        {
            <li>
                <ul>
                    <li>Name: @file.Name</li>
                    <li>Last modified: @file.LastModified.ToString()</li>
                    <li>Size (bytes): @file.Size</li>
                    <li>Content type: @file.ContentType</li>
                </ul>
            </li>
        }
    </ul>
}

@code {
    private List<IBrowserFile> loadedFiles = new();
    private long maxFileSize = 1024 * 15;
    private int maxAllowedFiles = 3;
    private bool isLoading;
    private decimal progressPercent;

    private async Task LoadFiles(InputFileChangeEventArgs e)
    {
        isLoading = true;
        loadedFiles.Clear();
        progressPercent = 0;

        foreach (var file in e.GetMultipleFiles(maxAllowedFiles))
        {
            try
            {
                var trustedFileName = Path.GetRandomFileName();
                var path = Path.Combine(Environment.ContentRootPath,
                    Environment.EnvironmentName, "unsafe_uploads", trustedFileName);

                await using FileStream writeStream = new(path, FileMode.Create);
                using var readStream = file.OpenReadStream(maxFileSize);
                var bytesRead = 0;
                var totalRead = 0;
                var buffer = new byte[1024 * 10];

                while ((bytesRead = await readStream.ReadAsync(buffer)) != 0)
                {
                    totalRead += bytesRead;

                    await writeStream.WriteAsync(buffer, 0, bytesRead);

                    progressPercent = Decimal.Divide(totalRead, file.Size);

                    StateHasChanged();
                }

                loadedFiles.Add(file);
            }
            catch (Exception ex)
            {
                Logger.LogError("File: {FileName} Error: {Error}", 
                    file.Name, ex.Message);
            }
        }

        isLoading = false;
    }
}

@page "/file-upload-3"
@using System 
@using System.IO
@using Microsoft.AspNetCore.Hosting
@using Microsoft.Extensions.Logging
@inject ILogger<FileUpload3> Logger
@inject IWebHostEnvironment Environment

<h3>Upload Files</h3>

<p>
    <label>
        Max file size:
        <input type="number" @bind="maxFileSize" />
    </label>
</p>

<p>
    <label>
        Max allowed files:
        <input type="number" @bind="maxAllowedFiles" />
    </label>
</p>

<p>
    <label>
        Upload up to @maxAllowedFiles of up to @maxFileSize bytes:
        <InputFile OnChange="LoadFiles" multiple />
    </label>
</p>

@if (isLoading)
{
    <p>Progress: @string.Format("{0:P0}", progressPercent)</p>
}
else
{
    <ul>
        @foreach (var file in loadedFiles)
        {
            <li>
                <ul>
                    <li>Name: @file.Name</li>
                    <li>Last modified: @file.LastModified.ToString()</li>
                    <li>Size (bytes): @file.Size</li>
                    <li>Content type: @file.ContentType</li>
                </ul>
            </li>
        }
    </ul>
}

@code {
    private List<IBrowserFile> loadedFiles = new();
    private long maxFileSize = 1024 * 15;
    private int maxAllowedFiles = 3;
    private bool isLoading;
    private decimal progressPercent;

    private async Task LoadFiles(InputFileChangeEventArgs e)
    {
        isLoading = true;
        loadedFiles.Clear();
        progressPercent = 0;

        foreach (var file in e.GetMultipleFiles(maxAllowedFiles))
        {
            try
            {
                var trustedFileName = Path.GetRandomFileName();
                var path = Path.Combine(Environment.ContentRootPath,
                    Environment.EnvironmentName, "unsafe_uploads", trustedFileName);

                await using FileStream writeStream = new(path, FileMode.Create);
                using var readStream = file.OpenReadStream(maxFileSize);
                var bytesRead = 0;
                var totalRead = 0;
                var buffer = new byte[1024 * 10];

                while ((bytesRead = await readStream.ReadAsync(buffer)) != 0)
                {
                    totalRead += bytesRead;

                    await writeStream.WriteAsync(buffer, 0, bytesRead);

                    progressPercent = Decimal.Divide(totalRead, file.Size);

                    StateHasChanged();
                }

                loadedFiles.Add(file);
            }
            catch (Exception ex)
            {
                Logger.LogError("File: {Filename} Error: {Error}", 
                    file.Name, ex.Message);
            }
        }

        isLoading = false;
    }
}

@page "/file-upload-3"
@using System 
@using System.IO
@using Microsoft.AspNetCore.Hosting
@using Microsoft.Extensions.Logging
@inject ILogger<FileUpload3> Logger
@inject IWebHostEnvironment Environment

<h3>Upload Files</h3>

<p>
    <label>
        Max file size:
        <input type="number" @bind="maxFileSize" />
    </label>
</p>

<p>
    <label>
        Max allowed files:
        <input type="number" @bind="maxAllowedFiles" />
    </label>
</p>

<p>
    <label>
        Upload up to @maxAllowedFiles of up to @maxFileSize bytes:
        <InputFile OnChange="LoadFiles" multiple />
    </label>
</p>

@if (isLoading)
{
    <p>Progress: @string.Format("{0:P0}", progressPercent)</p>
}
else
{
    <ul>
        @foreach (var file in loadedFiles)
        {
            <li>
                <ul>
                    <li>Name: @file.Name</li>
                    <li>Last modified: @file.LastModified.ToString()</li>
                    <li>Size (bytes): @file.Size</li>
                    <li>Content type: @file.ContentType</li>
                </ul>
            </li>
        }
    </ul>
}

@code {
    private List<IBrowserFile> loadedFiles = new();
    private long maxFileSize = 1024 * 15;
    private int maxAllowedFiles = 3;
    private bool isLoading;
    private decimal progressPercent;

    private async Task LoadFiles(InputFileChangeEventArgs e)
    {
        isLoading = true;
        loadedFiles.Clear();
        progressPercent = 0;

        foreach (var file in e.GetMultipleFiles(maxAllowedFiles))
        {
            try
            {
                var trustedFileName = Path.GetRandomFileName();
                var path = Path.Combine(Environment.ContentRootPath,
                    Environment.EnvironmentName, "unsafe_uploads", trustedFileName);

                await using FileStream writeStream = new(path, FileMode.Create);
                using var readStream = file.OpenReadStream(maxFileSize);
                var bytesRead = 0;
                var totalRead = 0;
                var buffer = new byte[1024 * 10];

                while ((bytesRead = await readStream.ReadAsync(buffer)) != 0)
                {
                    totalRead += bytesRead;

                    await writeStream.WriteAsync(buffer, 0, bytesRead);

                    progressPercent = Decimal.Divide(totalRead, file.Size);

                    StateHasChanged();
                }

                loadedFiles.Add(file);
            }
            catch (Exception ex)
            {
                Logger.LogError("File: {Filename} Error: {Error}", 
                    file.Name, ex.Message);
            }
        }

        isLoading = false;
    }
}

RemoteBrowserFileStreamOptions ermöglicht das Konfigurieren von Dateiuploadeigenschaften.

Bildvorschau beim Hochladen

Wenn Sie eine Bildvorschau beim Hochladen von Bildern wünschen, fügen Sie zunächst eine InputFile-Komponente mit einem Komponentenverweis und einem OnChange-Handler hinzu:

<InputFile @ref="inputFile" OnChange="ShowPreview" />

Fügen Sie ein Bildelement mit einem Elementverweis hinzu, der als Platzhalter für die Bildvorschau dient:

<img @ref="previewImageElem" />

Fügen Sie die zugehörigen Verweise hinzu:

@code {
    private InputFile? inputFile;
    private ElementReference previewImageElem;
}

Fügen Sie in JavaScript eine Funktion hinzu, die mit einem HTML-input- und img-Element aufgerufen wird und folgende Schritte ausführt:

• Extrahieren der ausgewählten Datei
• Erstellen einer Objekt-URL mit createObjectURL
• Festlegen eines Ereignislisteners, der die Objekt-URL nach dem Laden des Bilds mit revokeObjectURL widerruft, damit es nicht zu Arbeitsspeicherverlusten kommt
• Festlegen der Quelle des img-Elements, um das Bild anzuzeigen

window.previewImage = (inputElem, imgElem) => {
  const url = URL.createObjectURL(inputElem.files[0]);
  imgElem.addEventListener('load', () => URL.revokeObjectURL(url), { once: true });
  imgElem.src = url;
}

Verwenden Sie zum Schluss eine eingefügte IJSRuntime, um den OnChange-Handler hinzuzufügen, der die JavaScript-Funktion aufruft:

@inject IJSRuntime JS

...

@code {
    ...

    private async Task ShowPreview() => await JS.InvokeVoidAsync(
        "previewImage", inputFile!.Element, previewImageElem);
}

Im vorherigen Beispiel wird ein einzelnes Bild hochgeladen. Der Ansatz kann erweitert werden, um multiple-Bilder zu unterstützen.

Die folgende FileUpload4-Komponente zeigt das vollständige Beispiel.

FileUpload4.razor:

@page "/file-upload-4"
@inject IJSRuntime JS

<h1>File Upload Example</h1>

<InputFile @ref="inputFile" OnChange="ShowPreview" />

<img style="max-width:200px;max-height:200px" @ref="previewImageElem" />

@code {
    private InputFile? inputFile;
    private ElementReference previewImageElem;

    private async Task ShowPreview() => await JS.InvokeVoidAsync(
        "previewImage", inputFile!.Element, previewImageElem);
}

@page "/file-upload-4"
@inject IJSRuntime JS

<h1>File Upload Example</h1>

<InputFile @ref="inputFile" OnChange="ShowPreview" />

<img style="max-width:200px;max-height:200px" @ref="previewImageElem" />

@code {
    private InputFile? inputFile;
    private ElementReference previewImageElem;

    private async Task ShowPreview() => await JS.InvokeVoidAsync(
        "previewImage", inputFile!.Element, previewImageElem);
}

• Blazor-Dateidownloads in ASP.NET Core
• Hochladen von Dateien in ASP.NET Core
• Übersicht über ASP.NET Core Blazor-Formulare
• GitHub-Repository mit Blazor-Beispielen (dotnet/blazor-samples) (Informationen zum Herunterladen)

• Hochladen von Dateien in ASP.NET Core
• Übersicht über ASP.NET Core Blazor-Formulare
• GitHub-Repository mit Blazor-Beispielen (dotnet/blazor-samples) (Informationen zum Herunterladen)