BaseDataBoundControl.DataSource Proprietà

Definizione

Ottiene o imposta l'oggetto da cui il controllo con associazione a dati recupera il relativo elenco degli elementi di dati.

public:
 virtual property System::Object ^ DataSource { System::Object ^ get(); void set(System::Object ^ value); };
[System.ComponentModel.Bindable(true)]
[System.Web.UI.Themeable(false)]
public virtual object DataSource { get; set; }
[<System.ComponentModel.Bindable(true)>]
[<System.Web.UI.Themeable(false)>]
member this.DataSource : obj with get, set
Public Overridable Property DataSource As Object

Valore della proprietà

Oggetto che rappresenta l'origine dati da cui il controllo con associazione a dati recupera i dati. Il valore predefinito è null.

Attributi

Esempio

Nell'esempio di codice seguente viene illustrato come viene usata la DataSource proprietà di un controllo associato a dati. In questo esempio il GridView controllo è associato a un DataSet oggetto. Dopo aver impostato la DataSource proprietà, il DataBind metodo viene chiamato in modo esplicito.


<%@ Page language="C#" %>
<%@ import namespace="System.Data" %>
<%@ import namespace="System.Data.SqlClient" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">

  void Page_Load(Object sender, EventArgs e)
  {
    
    // This example uses Microsoft SQL Server and connects
    // to the Northwind sample database. The data source needs
    // to be bound to the GridView control only when the 
    // page is first loaded. Thereafter, the values are
    // stored in view state.                      
    if(!IsPostBack)
    {
        
      // Declare the query string.
      String queryString = 
        "Select [CustomerID], [CompanyName], [Address], [City], [PostalCode], [Country] From [Customers]";
        
      // Run the query and bind the resulting DataSet
      // to the GridView control.
      DataSet ds = GetData(queryString);
      if (ds.Tables.Count > 0)
      {
        AuthorsGridView.DataSource = ds;
        AuthorsGridView.DataBind();
      }
      else
      {
        Message.Text = "Unable to connect to the database.";
      }
            
    }     
    
  }
    
  DataSet GetData(String queryString)
  {

    // Retrieve the connection string stored in the Web.config file.
    String connectionString = ConfigurationManager.ConnectionStrings["NorthWindConnectionString"].ConnectionString;      
 
    DataSet ds = new DataSet();
        
    try
    {
      // Connect to the database and run the query.
      SqlConnection connection = new SqlConnection(connectionString);        
      SqlDataAdapter adapter = new SqlDataAdapter(queryString, connection);
        
      // Fill the DataSet.
      adapter.Fill(ds);
            
    }
    catch(Exception ex)
    {
        
      // The connection failed. Display an error message.
      Message.Text = "Unable to connect to the database.";
        
    }
        
    return ds;
        
  }
    
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head runat="server">
    <title>GridView DataBind Example</title>
</head>
<body>
    <form id="form1" runat="server">
        
      <h3>GridView DataBind Example</h3>
            
      <asp:label id="Message"
        forecolor="Red"
        runat="server"/>
               
      <br/>    

      <asp:gridview id="AuthorsGridView" 
        autogeneratecolumns="true" 
        runat="server">
      </asp:gridview>
                        
    </form>
  </body>
</html>

<%@ Page language="VB" %>
<%@ import namespace="System.Data" %>
<%@ import namespace="System.Data.SqlClient" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">

  Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)
    
    ' This example uses Microsoft SQL Server and connects
    ' to the Northwind sample database. The data source needs
    ' to be bound to the GridView control only when the 
    ' page is first loaded. Thereafter, the values are
    ' stored in view state.                      
    If Not IsPostBack Then
        
      ' Declare the query string.
      Dim queryString As String = _
        "Select [CustomerID], [CompanyName], [Address], [City], [PostalCode], [Country] From [Customers]"
        
      ' Run the query and bind the resulting DataSet
      ' to the GridView control.
      Dim ds As DataSet = GetData(queryString)
      If (ds.Tables.Count > 0) Then
      
        AuthorsGridView.DataSource = ds
        AuthorsGridView.DataBind()
      
      Else
      
        Message.Text = "Unable to connect to the database."
        
      End If
            
    End If
    
  End Sub
    
  Function GetData(ByVal queryString As String) As DataSet
    
    ' Retrieve the connection string stored in the Web.config file.
    Dim connectionString As String = ConfigurationManager.ConnectionStrings("NorthWindConnectionString").ConnectionString
 
    Dim ds As New DataSet()
        
    Try

      ' Connect to the database and run the query.
      Dim connection As New SqlConnection(connectionString)
      Dim adapter As New SqlDataAdapter(queryString, Connection)
        
      ' Fill the DataSet.
      Adapter.Fill(ds)
            
    
    Catch ex As Exception
        
      ' The connection failed. Display an error message.
      Message.Text = "Unable to connect to the database."
        
    End Try
        
    Return ds
        
  End Function
    
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head runat="server">
    <title>GridView DataBind Example</title>
</head>
<body>
    <form id="form1" runat="server">
        
      <h3>GridView DataBind Example</h3>
            
      <asp:label id="Message"
        forecolor="Red"
        runat="server"/>
               
      <br/>    

      <asp:gridview id="AuthorsGridView" 
        autogeneratecolumns="true" 
        runat="server">
      </asp:gridview>
                        
    </form>
  </body>
</html>

Commenti

Quando si imposta la DataSource proprietà, viene chiamato il ValidateDataSource metodo . Inoltre, se il controllo associato ai dati è già stato inizializzato, il OnDataPropertyChanged metodo viene chiamato per impostare la RequiresDataBinding proprietà su true.

Questa proprietà non può essere impostata da temi oppure temi di fogli di stile. Per altre informazioni, vedere ThemeableAttribute e ASP.NET Temi e skin.

Si applica a

Vedi anche