DataGridViewComboBoxColumn Classe

Definizione

public ref class DataGridViewComboBoxColumn : System::Windows::Forms::DataGridViewColumn

[System.Drawing.ToolboxBitmap(typeof(System.Windows.Forms.DataGridViewComboBoxColumn), "DataGridViewComboBoxColumn.bmp")]
public class DataGridViewComboBoxColumn : System.Windows.Forms.DataGridViewColumn

[System.Drawing.ToolboxBitmap(typeof(System.Windows.Forms.DataGridViewComboBoxColumn), "DataGridViewComboBoxColumn")]
public class DataGridViewComboBoxColumn : System.Windows.Forms.DataGridViewColumn

[<System.Drawing.ToolboxBitmap(typeof(System.Windows.Forms.DataGridViewComboBoxColumn), "DataGridViewComboBoxColumn.bmp")>]
type DataGridViewComboBoxColumn = class
    inherit DataGridViewColumn

[<System.Drawing.ToolboxBitmap(typeof(System.Windows.Forms.DataGridViewComboBoxColumn), "DataGridViewComboBoxColumn")>]
type DataGridViewComboBoxColumn = class
    inherit DataGridViewColumn

Public Class DataGridViewComboBoxColumn
Inherits DataGridViewColumn

Ereditarietà

Object

DataGridViewElement

DataGridViewBand

DataGridViewColumn

DataGridViewComboBoxColumn

Attributi

ToolboxBitmapAttribute

Esempio

Nell'esempio di codice seguente viene illustrato come usare un DataGridViewComboBoxColumn oggetto per facilitare l'immissione dei dati nella TitleOfCourtesy colonna.

#using <System.Data.dll>
#using <System.Windows.Forms.dll>
#using <System.dll>
#using <System.Drawing.dll>

#using <System.Xml.dll>
#using <System.EnterpriseServices.dll>
#using <System.Transactions.dll>
using namespace System;
using namespace System::Data;
using namespace System::Data::SqlClient;
using namespace System::Windows::Forms;
using namespace System::Collections::Generic;
using namespace System::Drawing;

public ref class Employees : public Form
{
private:
    DataGridView^ DataGridView1;

private:
    DataGridView^ DataGridView2;

public:
    [STAThread]
    static void Main()
    {
        try
        {
            Application::EnableVisualStyles();
            Application::Run(gcnew Employees());
        }
        catch (Exception^ e)
        {
            MessageBox::Show(e->Message + e->StackTrace);
        }
    }

private:
    Dictionary<String^, bool>^ inOffice;

public:
    Employees()
    {
        DataGridView1 = gcnew DataGridView();
        DataGridView2 = gcnew DataGridView();
        connectionString =
            "Integrated Security=SSPI;Persist Security Info=False;" +
            "Initial Catalog=Northwind;Data Source=localhost";
        inOffice = gcnew Dictionary<String^, bool>;

        this->Load += gcnew EventHandler(this, &Employees::Form1_Load);
    }

private:
    void Form1_Load(System::Object^ /*sender*/, System::EventArgs^ /*e*/)
    {
        try
        {
            SetUpForm();
            SetUpDataGridView1();
            SetUpDataGridView2();
        }
        catch (SqlException^)
        {
            MessageBox::Show("The connection string <"
                + connectionString
                + "> failed to connect.  Modify it "
                + "to connect to a Northwind database accessible to "
                + "your system.",
                "ERROR", MessageBoxButtons::OK, MessageBoxIcon::Exclamation);
            Application::Exit();
        }
    }

private:
    void SetUpForm()
    {
        Size = System::Drawing::Size(800, 600);
        FlowLayoutPanel^ flowLayout = gcnew FlowLayoutPanel();
        flowLayout->FlowDirection = FlowDirection::TopDown;
        flowLayout->Dock = DockStyle::Fill;
        Controls->Add(flowLayout);

        flowLayout->Controls->Add(DataGridView1);
        flowLayout->Controls->Add(DataGridView2);
    }

private:
    void SetUpDataGridView2()
    {
        DataGridView2->Dock = DockStyle::Bottom;
        DataGridView2->TopLeftHeaderCell->Value = "Sales Details";
        DataGridView2->RowHeadersWidthSizeMode = 
            DataGridViewRowHeadersWidthSizeMode::AutoSizeToAllHeaders;
    }

private:
    void SetUpDataGridView1()
    {
        //DataGridView1.DataError += new 
          //  DataGridViewDataErrorEventHandler(DataGridView1_DataError);
        DataGridView1->CellContentClick += gcnew 
            DataGridViewCellEventHandler(this, &Employees::DataGridView1_CellContentClick);
        DataGridView1->CellValuePushed += gcnew 
            DataGridViewCellValueEventHandler(this, &Employees::DataGridView1_CellValuePushed);
        DataGridView1->CellValueNeeded += gcnew 
            DataGridViewCellValueEventHandler(this, &Employees::DataGridView1_CellValueNeeded);

        // Virtual mode is turned on so that the
        // unbound DataGridViewCheckBoxColumn will
        // keep its state when the bound columns are
        // sorted.       
        DataGridView1->VirtualMode = true;
        DataGridView1->AutoSize = true;
        DataGridView1->DataSource = Populate("SELECT * FROM Employees");
        DataGridView1->TopLeftHeaderCell->Value = "Employees";
        DataGridView1->RowHeadersWidthSizeMode = 
            DataGridViewRowHeadersWidthSizeMode::AutoSizeToAllHeaders;
        DataGridView1->ColumnHeadersHeightSizeMode = 
            DataGridViewColumnHeadersHeightSizeMode::AutoSize;
        DataGridView1->AutoSizeColumnsMode = 
            DataGridViewAutoSizeColumnsMode::AllCells;
        DataGridView1->AllowUserToAddRows = false;
        DataGridView1->AllowUserToDeleteRows = false;

        // The below autogenerated column is removed so 
        // a DataGridViewComboboxColumn could be used instead.
        DataGridView1->Columns->Remove(ColumnName::TitleOfCourtesy.ToString());
        DataGridView1->Columns->Remove(ColumnName::ReportsTo.ToString());

        AddLinkColumn();
        AddComboBoxColumns();
        AddButtonColumn();
        AddOutOfOfficeColumn();
    }

private:
    void AddComboBoxColumns()
    {
        DataGridViewComboBoxColumn^ comboboxColumn;
        comboboxColumn = CreateComboBoxColumn();
        SetAlternateChoicesUsingDataSource(comboboxColumn);
        comboboxColumn->HeaderText = "TitleOfCourtesy (via DataSource property)";
        DataGridView1->Columns->Insert(0, comboboxColumn);

        comboboxColumn = CreateComboBoxColumn();
        SetAlternateChoicesUsingItems(comboboxColumn);
        comboboxColumn->HeaderText = "TitleOfCourtesy (via Items property)";
        // Tack this example column onto the end.
        DataGridView1->Columns->Add(comboboxColumn);
    }

private:
    void AddLinkColumn()
    {
        DataGridViewLinkColumn^ links = gcnew DataGridViewLinkColumn();

        links->UseColumnTextForLinkValue = true;
        links->HeaderText = ColumnName::ReportsTo.ToString();
        links->DataPropertyName = ColumnName::ReportsTo.ToString();
        links->ActiveLinkColor = Color::White;
        links->LinkBehavior = LinkBehavior::SystemDefault;
        links->LinkColor = Color::Blue;
        links->TrackVisitedState = true;
        links->VisitedLinkColor = Color::YellowGreen;

        DataGridView1->Columns->Add(links);
    }

private:
    void SetAlternateChoicesUsingItems(
        DataGridViewComboBoxColumn^ comboboxColumn)
    {
        comboboxColumn->Items->AddRange("Mr.", "Ms.", "Mrs.", "Dr.");
    }

private:
    DataGridViewComboBoxColumn^ CreateComboBoxColumn()
    {
        DataGridViewComboBoxColumn^ column =
            gcnew DataGridViewComboBoxColumn();
        {
            column->DataPropertyName = ColumnName::TitleOfCourtesy.ToString();
            column->HeaderText = ColumnName::TitleOfCourtesy.ToString();
            column->DropDownWidth = 160;
            column->Width = 90;
            column->MaxDropDownItems = 3;
            column->FlatStyle = FlatStyle::Flat;
        }
        return column;
    }

private:
    void SetAlternateChoicesUsingDataSource(DataGridViewComboBoxColumn^ comboboxColumn)
    {
        {
            comboboxColumn->DataSource = RetrieveAlternativeTitles();
            comboboxColumn->ValueMember = ColumnName::TitleOfCourtesy.ToString();
            comboboxColumn->DisplayMember = comboboxColumn->ValueMember;
        }
    }

private:
    DataTable^ RetrieveAlternativeTitles()
    {
        return Populate("SELECT distinct TitleOfCourtesy FROM Employees");
    }

    String^ connectionString;

private:
    DataTable^ Populate(String^ sqlCommand)
    {
        SqlConnection^ northwindConnection = gcnew SqlConnection(connectionString);
        northwindConnection->Open();

        SqlCommand^ command = gcnew SqlCommand(sqlCommand, northwindConnection);
        SqlDataAdapter^ adapter = gcnew SqlDataAdapter();
        adapter->SelectCommand = command;

        DataTable^ table = gcnew DataTable();
        adapter->Fill(table);

        return table;
    }

    // Using an enum provides some abstraction between column index
    // and column name along with compile time checking, and gives
    // a handy place to store the column names.
    enum class ColumnName
    {
        EmployeeID,
        LastName,
        FirstName,
        Title,
        TitleOfCourtesy,
        BirthDate,
        HireDate,
        Address,
        City,
        Region,
        PostalCode,
        Country,
        HomePhone,
        Extension,
        Photo,
        Notes,
        ReportsTo,
        PhotoPath,
        OutOfOffice
    };

private:
    void AddButtonColumn()
    {
        DataGridViewButtonColumn^ buttons = gcnew DataGridViewButtonColumn();
        {
            buttons->HeaderText = "Sales";
            buttons->Text = "Sales";
            buttons->UseColumnTextForButtonValue = true;
            buttons->AutoSizeMode =
                DataGridViewAutoSizeColumnMode::AllCells;
            buttons->FlatStyle = FlatStyle::Standard;
            buttons->CellTemplate->Style->BackColor = Color::Honeydew;
            buttons->DisplayIndex = 0;
        }

        DataGridView1->Columns->Add(buttons);

    }

private:
    void AddOutOfOfficeColumn()
    {
        DataGridViewCheckBoxColumn^ column = gcnew DataGridViewCheckBoxColumn();
        {
            column->HeaderText = ColumnName::OutOfOffice.ToString();
            column->Name = ColumnName::OutOfOffice.ToString();
            column->AutoSizeMode = 
                DataGridViewAutoSizeColumnMode::DisplayedCells;
            column->FlatStyle = FlatStyle::Standard;
            column->ThreeState = true;
            column->CellTemplate = gcnew DataGridViewCheckBoxCell();
            column->CellTemplate->Style->BackColor = Color::Beige;
        }

        DataGridView1->Columns->Insert(0, column);
    }

private:
    void PopulateSales(DataGridViewCellEventArgs^ buttonClick)
    {

        String^ employeeID = DataGridView1->Rows[buttonClick->RowIndex]
            ->Cells[ColumnName::EmployeeID.ToString()]->Value->ToString();
        DataGridView2->DataSource = Populate("SELECT * FROM Orders WHERE EmployeeID = " + employeeID);
    }

    #pragma region "SQL Error handling"
private:
    void DataGridView1_DataError(Object^ sender, DataGridViewDataErrorEventArgs^ anError)
    {

        MessageBox::Show("Error happened " + anError->Context.ToString());

        if (anError->Context == DataGridViewDataErrorContexts::Commit)
        {
            MessageBox::Show("Commit error");
        }
        if (anError->Context == DataGridViewDataErrorContexts::CurrentCellChange)
        {
            MessageBox::Show("Cell change");
        }
        if (anError->Context == DataGridViewDataErrorContexts::Parsing)
        {
            MessageBox::Show("parsing error");
        }
        if (anError->Context == DataGridViewDataErrorContexts::LeaveControl)
        {
            MessageBox::Show("leave control error");
        }

        if (dynamic_cast<ConstraintException^>(anError->Exception) != nullptr)
        {
            DataGridView^ view = (DataGridView^)sender;
            view->Rows[anError->RowIndex]->ErrorText = "an error";
            view->Rows[anError->RowIndex]->Cells[anError->ColumnIndex]->ErrorText = "an error";

            anError->ThrowException = false;
        }
    }
    #pragma endregion

private:
    void DataGridView1_CellContentClick(Object^ /*sender*/, DataGridViewCellEventArgs^ e)
    {

        if (IsANonHeaderLinkCell(e))
        {
            MoveToLinked(e);
        }
        else if (IsANonHeaderButtonCell(e))
        {
            PopulateSales(e);
        }
    }

private:
    void MoveToLinked(DataGridViewCellEventArgs^ e)
    {
        String^ employeeId;
        Object^ value = DataGridView1->Rows[e->RowIndex]->Cells[e->ColumnIndex]->Value;
        if (dynamic_cast<DBNull^>(value) != nullptr) { return; }

        employeeId = value->ToString();
        DataGridViewCell^ boss = RetrieveSuperiorsLastNameCell(employeeId);
        if (boss != nullptr)
        {
            DataGridView1->CurrentCell = boss;
        }
    }

private:
    bool IsANonHeaderLinkCell(DataGridViewCellEventArgs^ cellEvent)
    {
        if (dynamic_cast<DataGridViewLinkColumn^>(DataGridView1->Columns[cellEvent->ColumnIndex]) != nullptr
             &&
            cellEvent->RowIndex != -1)
        { return true; }
        else { return false; }
    }

private:
    bool IsANonHeaderButtonCell(DataGridViewCellEventArgs^ cellEvent)
    {
        if (dynamic_cast<DataGridViewButtonColumn^>(DataGridView1->Columns[cellEvent->ColumnIndex]) != nullptr
             &&
            cellEvent->RowIndex != -1)
        { return true; }
        else { return (false); }
    }

private:
    DataGridViewCell^ RetrieveSuperiorsLastNameCell(String^ employeeId)
    {

        for each (DataGridViewRow^ row in DataGridView1->Rows)
        {
            if (row->IsNewRow) { return nullptr; }
            if (row->Cells[ColumnName::EmployeeID.ToString()]->Value->ToString()->Equals(employeeId))
            {
                return row->Cells[ColumnName::LastName.ToString()];
            }
        }
        return nullptr;
    }

    #pragma region "checkbox state"

private:
    void DataGridView1_CellValuePushed(Object^ sender,
        DataGridViewCellValueEventArgs^ e)
    {
        if (IsCheckBoxColumn(e->ColumnIndex))
        {
            String^ employeeId = GetKey(e);
            if (!inOffice->ContainsKey(employeeId))
            {
                inOffice->Add(employeeId, (Boolean)e->Value);
            }
            else
            {
                inOffice[employeeId] = (Boolean)e->Value;
            }
        }
    }

private:
    String^ GetKey(DataGridViewCellValueEventArgs^ cell)
    {
        return DataGridView1->Rows[cell->RowIndex]->
            Cells[ColumnName::EmployeeID.ToString()]->Value->ToString();
    }

private:
    void DataGridView1_CellValueNeeded(Object^ sender,
        DataGridViewCellValueEventArgs^ e)
    {

        if (IsCheckBoxColumn(e->ColumnIndex))
        {
            String^ employeeId = GetKey(e);
            if (!inOffice->ContainsKey(employeeId))
            {
                bool defaultValue = false;
                inOffice->Add(employeeId, defaultValue);
            }

            e->Value = inOffice[employeeId];
        }
    }

private:
    bool IsCheckBoxColumn(int columnIndex)
    {
        DataGridViewColumn^ outOfOfficeColumn =
            DataGridView1->Columns[ColumnName::OutOfOffice.ToString()];
        return (DataGridView1->Columns[columnIndex] == outOfOfficeColumn);
    }
    #pragma endregion
};

int main()
{
    Employees::Main();
}

using System;
using System.Data;
using System.Data.SqlClient;
using System.Windows.Forms;
using System.Collections.Generic;
using System.Drawing;

public class Employees : Form
{
    private DataGridView DataGridView1 = new DataGridView();
    private DataGridView DataGridView2 = new DataGridView();

    [STAThread]
    public static void Main()
    {
        try
        {
            Application.EnableVisualStyles();
            Application.Run(new Employees());
        }
        catch (Exception e)
        {
            MessageBox.Show(e.Message + e.StackTrace);
        }
    }

    public Employees()
    {
        this.Load += new EventHandler(Form1_Load);
    }

    private void Form1_Load(System.Object sender, System.EventArgs e)
    {
        try
        {
            SetUpForm();
            SetUpDataGridView1();
            SetUpDataGridView2();
        }
        catch (SqlException)
        {
            MessageBox.Show("The connection string <"
                + connectionString
                + "> failed to connect.  Modify it "
                + "to connect to a Northwind database accessible to "
                + "your system.",
                "ERROR", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
            Application.Exit();
        }
    }

    private void SetUpForm()
    {
        Size = new Size(800, 600);
        FlowLayoutPanel flowLayout = new FlowLayoutPanel();
        flowLayout.FlowDirection = FlowDirection.TopDown;
        flowLayout.Dock = DockStyle.Fill;
        Controls.Add(flowLayout);
        Text = "DataGridView columns demo";

        flowLayout.Controls.Add(DataGridView1);
        flowLayout.Controls.Add(DataGridView2);
    }

    private void SetUpDataGridView2()
    {
        DataGridView2.Dock = DockStyle.Bottom;
        DataGridView2.TopLeftHeaderCell.Value = "Sales Details";
        DataGridView2.RowHeadersWidthSizeMode = 
            DataGridViewRowHeadersWidthSizeMode.AutoSizeToAllHeaders;
    }

    private void SetUpDataGridView1()
    {
        DataGridView1.DataError += new 
            DataGridViewDataErrorEventHandler(DataGridView1_DataError);
        DataGridView1.CellContentClick += new 
            DataGridViewCellEventHandler(DataGridView1_CellContentClick);
        DataGridView1.CellValuePushed += new 
            DataGridViewCellValueEventHandler(DataGridView1_CellValuePushed);
        DataGridView1.CellValueNeeded += new 
            DataGridViewCellValueEventHandler(DataGridView1_CellValueNeeded);

        // Virtual mode is turned on so that the
        // unbound DataGridViewCheckBoxColumn will
        // keep its state when the bound columns are
        // sorted.       
        DataGridView1.VirtualMode = true;
        DataGridView1.AutoSize = true;
        DataGridView1.DataSource = Populate("SELECT * FROM Employees");
        DataGridView1.TopLeftHeaderCell.Value = "Employees";
        DataGridView1.RowHeadersWidthSizeMode = 
            DataGridViewRowHeadersWidthSizeMode.AutoSizeToAllHeaders;
        DataGridView1.ColumnHeadersHeightSizeMode = 
            DataGridViewColumnHeadersHeightSizeMode.AutoSize;
        DataGridView1.AutoSizeColumnsMode = 
            DataGridViewAutoSizeColumnsMode.AllCells;
        DataGridView1.AllowUserToAddRows = false;
        DataGridView1.AllowUserToDeleteRows = false;

        // The below autogenerated column is removed so 
        // a DataGridViewComboboxColumn could be used instead.
        DataGridView1.Columns.Remove(ColumnName.TitleOfCourtesy.ToString());
        DataGridView1.Columns.Remove(ColumnName.ReportsTo.ToString());

        AddLinkColumn();
        AddComboBoxColumns();
        AddButtonColumn();
        AddOutOfOfficeColumn();
    }

    private void AddComboBoxColumns()
    {
        DataGridViewComboBoxColumn comboboxColumn;
        comboboxColumn = CreateComboBoxColumn();
        SetAlternateChoicesUsingDataSource(comboboxColumn);
        comboboxColumn.HeaderText = "TitleOfCourtesy (via DataSource property)";
        DataGridView1.Columns.Insert(0, comboboxColumn);

        comboboxColumn = CreateComboBoxColumn();
        SetAlternateChoicesUsingItems(comboboxColumn);
        comboboxColumn.HeaderText = "TitleOfCourtesy (via Items property)";
        // Tack this example column onto the end.
        DataGridView1.Columns.Add(comboboxColumn);
    }

    private void AddLinkColumn()
    {
        DataGridViewLinkColumn links = new DataGridViewLinkColumn();

        links.UseColumnTextForLinkValue = true;
        links.HeaderText = ColumnName.ReportsTo.ToString();
        links.DataPropertyName = ColumnName.ReportsTo.ToString();
        links.ActiveLinkColor = Color.White;
        links.LinkBehavior = LinkBehavior.SystemDefault;
        links.LinkColor = Color.Blue;
        links.TrackVisitedState = true;
        links.VisitedLinkColor = Color.YellowGreen;

        DataGridView1.Columns.Add(links);
    }

    private static void SetAlternateChoicesUsingItems(
        DataGridViewComboBoxColumn comboboxColumn)
    {
        comboboxColumn.Items.AddRange("Mr.", "Ms.", "Mrs.", "Dr.");
    }

    private DataGridViewComboBoxColumn CreateComboBoxColumn()
    {
        DataGridViewComboBoxColumn column =
            new DataGridViewComboBoxColumn();
        {
            column.DataPropertyName = ColumnName.TitleOfCourtesy.ToString();
            column.HeaderText = ColumnName.TitleOfCourtesy.ToString();
            column.DropDownWidth = 160;
            column.Width = 90;
            column.MaxDropDownItems = 3;
            column.FlatStyle = FlatStyle.Flat;
        }
        return column;
    }

    private void SetAlternateChoicesUsingDataSource(DataGridViewComboBoxColumn comboboxColumn)
    {
        {
            comboboxColumn.DataSource = RetrieveAlternativeTitles();
            comboboxColumn.ValueMember = ColumnName.TitleOfCourtesy.ToString();
            comboboxColumn.DisplayMember = comboboxColumn.ValueMember;
        }
    }

    private DataTable RetrieveAlternativeTitles()
    {
        return Populate("SELECT distinct TitleOfCourtesy FROM Employees");
    }

    string connectionString =
        "Integrated Security=SSPI;Persist Security Info=False;" +
        "Initial Catalog=Northwind;Data Source=localhost";

    private DataTable Populate(string sqlCommand)
    {
        SqlConnection northwindConnection = new SqlConnection(connectionString);
        northwindConnection.Open();

        SqlCommand command = new SqlCommand(sqlCommand, northwindConnection);
        SqlDataAdapter adapter = new SqlDataAdapter();
        adapter.SelectCommand = command;

        DataTable table = new DataTable();
        table.Locale = System.Globalization.CultureInfo.InvariantCulture;
        adapter.Fill(table);

        return table;
    }

    // Using an enum provides some abstraction between column index
    // and column name along with compile time checking, and gives
    // a handy place to store the column names.
    enum ColumnName
    {
        EmployeeId,
        LastName,
        FirstName,
        Title,
        TitleOfCourtesy,
        BirthDate,
        HireDate,
        Address,
        City,
        Region,
        PostalCode,
        Country,
        HomePhone,
        Extension,
        Photo,
        Notes,
        ReportsTo,
        PhotoPath,
        OutOfOffice
    };

    private void AddButtonColumn()
    {
        DataGridViewButtonColumn buttons = new DataGridViewButtonColumn();
        {
            buttons.HeaderText = "Sales";
            buttons.Text = "Sales";
            buttons.UseColumnTextForButtonValue = true;
            buttons.AutoSizeMode =
                DataGridViewAutoSizeColumnMode.AllCells;
            buttons.FlatStyle = FlatStyle.Standard;
            buttons.CellTemplate.Style.BackColor = Color.Honeydew;
            buttons.DisplayIndex = 0;
        }

        DataGridView1.Columns.Add(buttons);
    }

    private void AddOutOfOfficeColumn()
    {
        DataGridViewCheckBoxColumn column = new DataGridViewCheckBoxColumn();
        {
            column.HeaderText = ColumnName.OutOfOffice.ToString();
            column.Name = ColumnName.OutOfOffice.ToString();
            column.AutoSizeMode = 
                DataGridViewAutoSizeColumnMode.DisplayedCells;
            column.FlatStyle = FlatStyle.Standard;
            column.ThreeState = true;
            column.CellTemplate = new DataGridViewCheckBoxCell();
            column.CellTemplate.Style.BackColor = Color.Beige;
        }

        DataGridView1.Columns.Insert(0, column);
    }

    private void PopulateSales(DataGridViewCellEventArgs buttonClick)
    {

        string employeeId = DataGridView1.Rows[buttonClick.RowIndex]
            .Cells[ColumnName.EmployeeId.ToString()].Value.ToString();
        DataGridView2.DataSource = Populate("SELECT * FROM Orders WHERE EmployeeId = " + employeeId);
    }

    #region "SQL Error handling"
    private void DataGridView1_DataError(object sender, DataGridViewDataErrorEventArgs anError)
    {

        MessageBox.Show("Error happened " + anError.Context.ToString());

        if (anError.Context == DataGridViewDataErrorContexts.Commit)
        {
            MessageBox.Show("Commit error");
        }
        if (anError.Context == DataGridViewDataErrorContexts.CurrentCellChange)
        {
            MessageBox.Show("Cell change");
        }
        if (anError.Context == DataGridViewDataErrorContexts.Parsing)
        {
            MessageBox.Show("parsing error");
        }
        if (anError.Context == DataGridViewDataErrorContexts.LeaveControl)
        {
            MessageBox.Show("leave control error");
        }

        if ((anError.Exception) is ConstraintException)
        {
            DataGridView view = (DataGridView)sender;
            view.Rows[anError.RowIndex].ErrorText = "an error";
            view.Rows[anError.RowIndex].Cells[anError.ColumnIndex].ErrorText = "an error";

            anError.ThrowException = false;
        }
    }
    #endregion

    private void DataGridView1_CellContentClick(object sender, DataGridViewCellEventArgs e)
    {

        if (IsANonHeaderLinkCell(e))
        {
            MoveToLinked(e);
        }
        else if (IsANonHeaderButtonCell(e))
        {
            PopulateSales(e);
        }
    }

    private void MoveToLinked(DataGridViewCellEventArgs e)
    {
        string employeeId;
        object value = DataGridView1.Rows[e.RowIndex].Cells[e.ColumnIndex].Value;
        if (value is DBNull) { return; }

        employeeId = value.ToString();
        DataGridViewCell boss = RetrieveSuperiorsLastNameCell(employeeId);
        if (boss != null)
        {
            DataGridView1.CurrentCell = boss;
        }
    }

    private bool IsANonHeaderLinkCell(DataGridViewCellEventArgs cellEvent)
    {
        if (DataGridView1.Columns[cellEvent.ColumnIndex] is
            DataGridViewLinkColumn &&
            cellEvent.RowIndex != -1)
        { return true; }
        else { return false; }
    }

    private bool IsANonHeaderButtonCell(DataGridViewCellEventArgs cellEvent)
    {
        if (DataGridView1.Columns[cellEvent.ColumnIndex] is
            DataGridViewButtonColumn &&
            cellEvent.RowIndex != -1)
        { return true; }
        else { return (false); }
    }

    private DataGridViewCell RetrieveSuperiorsLastNameCell(string employeeId)
    {

        foreach (DataGridViewRow row in DataGridView1.Rows)
        {
            if (row.IsNewRow) { return null; }
            if (row.Cells[ColumnName.EmployeeId.ToString()].Value.ToString().Equals(employeeId))
            {
                return row.Cells[ColumnName.LastName.ToString()];
            }
        }
        return null;
    }

    #region "checkbox state"
    Dictionary<string, bool> inOffice = new Dictionary<string, bool>();
    private void DataGridView1_CellValuePushed(object sender,
        DataGridViewCellValueEventArgs e)
    {
        if (IsCheckBoxColumn(e.ColumnIndex))
        {
            string employeeId = GetKey(e);
            if (!inOffice.ContainsKey(employeeId))
            {
                inOffice.Add(employeeId, (Boolean)e.Value);
            }
            else
            {
                inOffice[employeeId] = (Boolean)e.Value;
            }
        }
    }

    private string GetKey(DataGridViewCellValueEventArgs cell)
    {
        return DataGridView1.Rows[cell.RowIndex].
            Cells[ColumnName.EmployeeId.ToString()].Value.ToString();
    }

    private void DataGridView1_CellValueNeeded(object sender,
        DataGridViewCellValueEventArgs e)
    {

        if (IsCheckBoxColumn(e.ColumnIndex))
        {
            string employeeId = GetKey(e);
            if (!inOffice.ContainsKey(employeeId))
            {
                bool defaultValue = false;
                inOffice.Add(employeeId, defaultValue);
            }

            e.Value = inOffice[employeeId];
        }
    }

    private bool IsCheckBoxColumn(int columnIndex)
    {
        DataGridViewColumn outOfOfficeColumn =
            DataGridView1.Columns[ColumnName.OutOfOffice.ToString()];
        return (DataGridView1.Columns[columnIndex] == outOfOfficeColumn);
    }
    #endregion
}

Imports System.Data
Imports System.Data.SqlClient
Imports System.Windows.Forms
Imports System.Collections.Generic
Imports System.Drawing

Public Class Employees
    Inherits System.Windows.Forms.Form

    Private WithEvents DataGridView1 As New DataGridView
    Private WithEvents DataGridView2 As New DataGridView

    <STAThreadAttribute()> _
    Public Shared Sub Main()
        Try
            Application.EnableVisualStyles()
            Application.Run(New Employees())
        Catch e As Exception
            MessageBox.Show(e.Message & e.StackTrace)
        End Try
    End Sub

    Private Sub Form1_Load(ByVal sender As System.Object, _
        ByVal e As System.EventArgs) Handles MyBase.Load

        Try
            SetUpForm()
            SetUpDataGridView1()
            SetUpDataGridView2()
        Catch ex As SqlException
            MessageBox.Show("The connection string <" _
                & connectionString _
                & "> failed to connect.  Modify it to connect to " _
                & "a Northwind database accessible to your system.", _
                "ERROR", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
            Application.Exit()
        End Try
    End Sub

    Private Sub SetUpForm()
        Size = New Size(800, 600)
        Dim flowLayout As New FlowLayoutPanel()
        flowLayout.FlowDirection = FlowDirection.TopDown
        flowLayout.Dock = DockStyle.Fill
        Controls.Add(flowLayout)
        Text = "DataGridView columns demo"

        flowLayout.Controls.Add(DataGridView1)
        flowLayout.Controls.Add(DataGridView2)
    End Sub

    Private Sub SetUpDataGridView2()
        DataGridView2.Dock = DockStyle.Bottom
        DataGridView2.TopLeftHeaderCell.Value = "Sales Details"
        DataGridView2.RowHeadersWidthSizeMode = _
        DataGridViewRowHeadersWidthSizeMode.AutoSizeToAllHeaders
    End Sub

    Private Sub SetUpDataGridView1()
        ' Virtual mode is turned on so that the
        ' unbound DataGridViewCheckBoxColumn will
        ' keep its state when the bound columns are
        ' sorted.
        DataGridView1.VirtualMode = True

        DataGridView1.AutoSize = True
        DataGridView1.DataSource = _
            Populate("SELECT * FROM Employees")
        DataGridView1.TopLeftHeaderCell.Value = "Employees"
        DataGridView1.RowHeadersWidthSizeMode = _
            DataGridViewRowHeadersWidthSizeMode.AutoSizeToAllHeaders
        DataGridView1.ColumnHeadersHeightSizeMode = _
            DataGridViewColumnHeadersHeightSizeMode.AutoSize
        DataGridView1.AutoSizeColumnsMode = _
            DataGridViewAutoSizeColumnsMode.AllCells
        DataGridView1.AllowUserToAddRows = False
        DataGridView1.AllowUserToDeleteRows = False

        ' The below autogenerated column is removed so 
        ' a DataGridViewComboboxColumn could be used instead.
        DataGridView1.Columns.Remove( _
            ColumnName.TitleOfCourtesy.ToString())
        DataGridView1.Columns.Remove(ColumnName.ReportsTo.ToString())

        AddLinkColumn()
        AddComboBoxColumns()
        AddButtonColumn()
        AddOutOfOfficeColumn()
    End Sub

    Private Sub AddComboBoxColumns()
        Dim comboboxColumn As DataGridViewComboBoxColumn
        comboboxColumn = CreateComboBoxColumn()
        SetAlternateChoicesUsingDataSource(comboboxColumn)
        comboboxColumn.HeaderText = _
            "TitleOfCourtesy (via DataSource property)"
        DataGridView1.Columns.Insert(0, comboboxColumn)

        comboboxColumn = CreateComboBoxColumn()
        SetAlternateChoicesUsingItems(comboboxColumn)
        comboboxColumn.HeaderText = _
            "TitleOfCourtesy (via Items property)"
        ' Tack this example column onto the end.
        DataGridView1.Columns.Add(comboboxColumn)
    End Sub

    Private Sub AddLinkColumn()

        Dim links As New DataGridViewLinkColumn()
        With links
            .UseColumnTextForLinkValue = True
            .HeaderText = ColumnName.ReportsTo.ToString()
            .DataPropertyName = ColumnName.ReportsTo.ToString()
            .ActiveLinkColor = Color.White
            .LinkBehavior = LinkBehavior.SystemDefault
            .LinkColor = Color.Blue
            .TrackVisitedState = True
            .VisitedLinkColor = Color.YellowGreen
        End With
        DataGridView1.Columns.Add(links)
    End Sub

    Private Shared Sub SetAlternateChoicesUsingItems( _
        ByVal comboboxColumn As DataGridViewComboBoxColumn)

        comboboxColumn.Items.AddRange("Mr.", "Ms.", "Mrs.", "Dr.")

    End Sub

    Private Function CreateComboBoxColumn() _
        As DataGridViewComboBoxColumn
        Dim column As New DataGridViewComboBoxColumn()

        With column
            .DataPropertyName = ColumnName.TitleOfCourtesy.ToString()
            .HeaderText = ColumnName.TitleOfCourtesy.ToString()
            .DropDownWidth = 160
            .Width = 90
            .MaxDropDownItems = 3
            .FlatStyle = FlatStyle.Flat
        End With
        Return column
    End Function

    Private Sub SetAlternateChoicesUsingDataSource( _
        ByVal comboboxColumn As DataGridViewComboBoxColumn)
        With comboboxColumn
            .DataSource = RetrieveAlternativeTitles()
            .ValueMember = ColumnName.TitleOfCourtesy.ToString()
            .DisplayMember = .ValueMember
        End With
    End Sub

    Private Function RetrieveAlternativeTitles() As DataTable
        Return Populate( _
            "SELECT distinct TitleOfCourtesy FROM Employees")
    End Function

    Private connectionString As String = _
            "Integrated Security=SSPI;Persist Security Info=False;" _
            & "Initial Catalog=Northwind;Data Source=localhost"

    Private Function Populate(ByVal sqlCommand As String) As DataTable
        Dim northwindConnection As New SqlConnection(connectionString)
        northwindConnection.Open()

        Dim command As New SqlCommand(sqlCommand, _
            northwindConnection)
        Dim adapter As New SqlDataAdapter()
        adapter.SelectCommand = command
        Dim table As New DataTable()
        table.Locale = System.Globalization.CultureInfo.InvariantCulture
        adapter.Fill(table)

        Return table
    End Function

    ' Using an enum provides some abstraction between column index
    ' and column name along with compile time checking, and gives
    ' a handy place to store the column names.
    Enum ColumnName
        EmployeeId
        LastName
        FirstName
        Title
        TitleOfCourtesy
        BirthDate
        HireDate
        Address
        City
        Region
        PostalCode
        Country
        HomePhone
        Extension
        Photo
        Notes
        ReportsTo
        PhotoPath
        OutOfOffice
    End Enum

    Private Sub AddButtonColumn()
        Dim buttons As New DataGridViewButtonColumn()
        With buttons
            .HeaderText = "Sales"
            .Text = "Sales"
            .UseColumnTextForButtonValue = True
            .AutoSizeMode = DataGridViewAutoSizeColumnMode.DisplayedCells
            .FlatStyle = FlatStyle.Standard
            .CellTemplate.Style.BackColor = Color.Honeydew
            .DisplayIndex = 0
        End With

        DataGridView1.Columns.Add(buttons)

    End Sub

    Private Sub AddOutOfOfficeColumn()
        Dim column As New DataGridViewCheckBoxColumn()
        With column
            .HeaderText = ColumnName.OutOfOffice.ToString()
            .Name = ColumnName.OutOfOffice.ToString()
            .AutoSizeMode = DataGridViewAutoSizeColumnMode.DisplayedCells
            .FlatStyle = FlatStyle.Standard
            .CellTemplate = New DataGridViewCheckBoxCell()
            .CellTemplate.Style.BackColor = Color.Beige
        End With

        DataGridView1.Columns.Insert(0, column)
    End Sub

    Private Sub PopulateSales( _
        ByVal buttonClick As DataGridViewCellEventArgs)

        Dim employeeId As String = _
            DataGridView1.Rows(buttonClick.RowIndex). _
            Cells(ColumnName.EmployeeId.ToString()).Value().ToString()
        DataGridView2.DataSource = Populate( _
            "SELECT * FROM Orders WHERE EmployeeId = " & employeeId)
    End Sub

#Region "SQL Error handling"
    Private Sub DataGridView1_DataError(ByVal sender As Object, _
    ByVal e As DataGridViewDataErrorEventArgs) _
    Handles DataGridView1.DataError

        MessageBox.Show("Error happened " _
            & e.Context.ToString())

        If (e.Context = DataGridViewDataErrorContexts.Commit) _
            Then
            MessageBox.Show("Commit error")
        End If
        If (e.Context = DataGridViewDataErrorContexts _
            .CurrentCellChange) Then
            MessageBox.Show("Cell change")
        End If
        If (e.Context = DataGridViewDataErrorContexts.Parsing) _
            Then
            MessageBox.Show("parsing error")
        End If
        If (e.Context = _
            DataGridViewDataErrorContexts.LeaveControl) Then
            MessageBox.Show("leave control error")
        End If

        If (TypeOf (e.Exception) Is ConstraintException) Then
            Dim view As DataGridView = CType(sender, DataGridView)
            view.Rows(e.RowIndex).ErrorText = "an error"
            view.Rows(e.RowIndex).Cells(e.ColumnIndex) _
                .ErrorText = "an error"

            e.ThrowException = False
        End If
    End Sub
#End Region

    Private Sub DataGridView1_CellContentClick(ByVal sender As Object, _
        ByVal e As DataGridViewCellEventArgs) _
        Handles DataGridView1.CellContentClick

        If IsANonHeaderLinkCell(e) Then
            MoveToLinked(e)
        ElseIf IsANonHeaderButtonCell(e) Then
            PopulateSales(e)
        End If
    End Sub

    Private Sub MoveToLinked(ByVal e As DataGridViewCellEventArgs)
        Dim employeeId As String
        Dim value As Object = DataGridView1.Rows(e.RowIndex). _
            Cells(e.ColumnIndex).Value
        If value.GetType Is GetType(DBNull) Then Return

        employeeId = CType(value, String)
        Dim boss As DataGridViewCell = _
            RetrieveSuperiorsLastNameCell(employeeId)
        If boss IsNot Nothing Then
            DataGridView1.CurrentCell = boss
        End If
    End Sub

    Private Function IsANonHeaderLinkCell(ByVal cellEvent As _
        DataGridViewCellEventArgs) As Boolean

        If TypeOf DataGridView1.Columns(cellEvent.ColumnIndex) _
            Is DataGridViewLinkColumn _
            AndAlso Not cellEvent.RowIndex = -1 Then _
            Return True Else Return False

    End Function

    Private Function IsANonHeaderButtonCell(ByVal cellEvent As _
        DataGridViewCellEventArgs) As Boolean

        If TypeOf DataGridView1.Columns(cellEvent.ColumnIndex) _
            Is DataGridViewButtonColumn _
            AndAlso Not cellEvent.RowIndex = -1 Then _
            Return True Else Return (False)

    End Function

    Private Function RetrieveSuperiorsLastNameCell( _
        ByVal employeeId As String) As DataGridViewCell

        For Each row As DataGridViewRow In DataGridView1.Rows
            If row.IsNewRow Then Return Nothing
            If row.Cells(ColumnName.EmployeeId.ToString()). _
                Value.ToString().Equals(employeeId) Then
                Return row.Cells(ColumnName.LastName.ToString())
            End If
        Next
        Return Nothing
    End Function

#Region "checkbox state"
    Dim inOffice As New Dictionary(Of String, Boolean)
    Private Sub DataGridView1_CellValuePushed(ByVal sender As Object, _
     ByVal e As DataGridViewCellValueEventArgs) _
        Handles DataGridView1.CellValuePushed

        If IsCheckBoxColumn(e.ColumnIndex) Then
            Dim employeeId As String = GetKey(e)
            If Not inOffice.ContainsKey(employeeId) Then
                inOffice.Add(employeeId, CType(e.Value, Boolean))
            Else
                inOffice.Item(employeeId) = CType(e.Value, Boolean)
            End If
        End If
    End Sub

    Private Function GetKey(ByVal cell As DataGridViewCellValueEventArgs) As String
        Return DataGridView1.Rows(cell.RowIndex).Cells( _
            ColumnName.EmployeeId.ToString()).Value().ToString()
    End Function

    Private Sub DataGridView1_CellValueNeeded(ByVal sender As Object, _
     ByVal e As DataGridViewCellValueEventArgs) _
        Handles DataGridView1.CellValueNeeded

        If IsCheckBoxColumn(e.ColumnIndex) Then
            Dim employeeId As String = GetKey(e)
            If Not inOffice.ContainsKey(employeeId) Then
                Dim defaultValue As Boolean = False
                inOffice.Add(employeeId, defaultValue)
            End If

            e.Value = inOffice.Item(employeeId)
        End If
    End Sub

    Private Function IsCheckBoxColumn(ByVal columnIndex As Integer) As Boolean

        Dim outOfOfficeColumn As DataGridViewColumn = _
            DataGridView1.Columns(ColumnName.OutOfOffice.ToString())
        Return (DataGridView1.Columns(columnIndex) Is outOfOfficeColumn)

    End Function
#End Region

End Class

Commenti

La DataGridViewComboBoxColumn classe è un tipo specializzato di DataGridViewColumn usato per ospitare logicamente le celle che consentono agli utenti di selezionare i valori da un elenco di scelte. Un oggetto DataGridViewComboBoxColumn ha un oggetto associato DataGridViewComboBoxCell in ogni DataGridViewRow oggetto che lo interseca.

È possibile popolare manualmente le celle impostandone Value le proprietà. In alternativa, è possibile associare la colonna all'origine DataGridView.DataSource dati indicata dalla proprietà . Se l'oggetto DataGridView è associato a una tabella di database, impostare la proprietà column DataPropertyName sul nome di una colonna nella tabella. Se l'oggetto DataGridView è associato a una raccolta di oggetti, impostare la DataPropertyName proprietà sul nome di una proprietà oggetto.

È possibile popolare manualmente l'elenco a discesa della colonna aggiungendo valori alla Items raccolta. In alternativa, è possibile associare l'elenco a discesa alla propria origine dati impostando la proprietà column DataSource . Se i valori sono oggetti in una raccolta o record in una tabella di database, è necessario impostare anche le DisplayMember proprietà e ValueMember . La DisplayMember proprietà indica quale proprietà oggetto o colonna di database fornisce i valori visualizzati nell'elenco a discesa. La ValueMember proprietà indica quale proprietà oggetto o colonna di database viene usata per impostare la proprietà cell Value .

Uno scenario tipico consiste nell'associare il controllo a una tabella del database padre e associare l'elenco DataGridView a discesa a una tabella figlio correlata. Ad esempio, è possibile associare il DataGridView controllo a una Orders tabella contenente una ProductID colonna e impostare la proprietà della colonna DataSource su una Products tabella contenente ProductID e ProductName colonne. In questo caso, si imposta la proprietà column DataPropertyName su "ProductID" per popolare i relativi valori di Orders.ProductID cella dalla colonna. Tuttavia, per visualizzare i nomi dei prodotti effettivi nelle celle e l'elenco a discesa, è necessario eseguire il mapping di questi valori alla Products tabella impostando la proprietà su "ProductID" e la ValueMemberDisplayMember proprietà su "ProductName".

I valori dell'elenco ValueMember a discesa (o i valori indicati dalla proprietà) devono includere i valori effettivi della cella o il controllo genererà un'eccezione DataGridView .

L'impostazione della colonna , DisplayMembere ValueMember delle proprietà imposta automaticamente le proprietà corrispondenti di tutte le celle della colonnaDataSource, tra cui .CellTemplate Per eseguire l'override di questi valori di proprietà per celle specifiche, impostare prima la proprietà della colonna e quindi impostare le proprietà della cella.

A differenza del controllo, l'oggetto ComboBoxDataGridViewComboBoxCell non ha SelectedIndex e SelectedValue proprietà. Selezionare invece un valore da un elenco a discesa imposta la proprietà cella Value .

La modalità di ordinamento predefinita per questo tipo di colonna è NotSortable.

Note per gli eredi

Quando si deriva da DataGridViewComboBoxColumn e si aggiungono nuove proprietà alla classe derivata, assicurarsi di eseguire l'override del Clone() metodo per copiare le nuove proprietà durante le operazioni di clonazione. È anche necessario chiamare il metodo della Clone() classe base in modo che le proprietà della classe di base vengano copiate nella nuova cella.

Costruttori

Proprietà

Metodi

Eventi

Si applica a

Vedi anche

• DataGridView
• DataSource
• DataPropertyName
• DataSource
• Items
• ValueMember
• DisplayMember
• DataGridViewColumn
• DataGridViewRow
• DataGridViewComboBoxCell
• DataGridViewComboBoxEditingControl
• SortMode
• Procedura: Accedere agli oggetti in un elenco a discesa DataGridViewComboBoxCell di Windows Forms