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HtmlSelect.DataMember Proprietà

Definizione

Ottiene o imposta l'insieme di dati da associare al controllo HtmlSelect da una proprietà DataSource con più insiemi di dati.

public:
 virtual property System::String ^ DataMember { System::String ^ get(); void set(System::String ^ value); };
public virtual string DataMember { get; set; }
member this.DataMember : string with get, set
Public Overridable Property DataMember As String

Valore della proprietà

String

L'insieme di dati da associare al controllo HtmlSelect ottenuti da una proprietà DataSource con più insiemi di dati. Il valore predefinito è una stringa vuota (""), che indica che questa proprietà non è stata impostata.

Eccezioni

La proprietà DataMember viene impostata durante la fase di associazione dati del controllo HtmlSelect.

Esempio

Nell'esempio di codice seguente viene illustrato come utilizzare la DataMember proprietà per specificare un set di dati da associare al HtmlSelect controllo da una DataSource proprietà con più set di dati.

<%@ Page Language="C#" AutoEventWireup="True" %>
<%@ 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">
<html xmlns="http://www.w3.org/1999/xhtml" >

<head>
    <title> HtmlSelect Example </title>
<script runat="server">

      void Page_Load (Object sender, EventArgs e)
      {

         // Bind the HtmlSelect control to a data source when the page is initially loaded.
         if (!IsPostBack)
         {
      
            // Create a data set to store the tables.
            DataSet ds = new DataSet("TitleDataSet");
            DataRow dr; 

            // Create the authors table with a single column.
            DataTable authors = new DataTable("Authors");            
            authors.Columns.Add(new DataColumn("LName", typeof(string)));                    
 
            // Add the authors table to the data set.
            ds.Tables.Add(authors);

            // Create sample data in the authors table.
            for (int i = 0; i < 9; i++) 
            {
               // Create a new row for the authors table.
               dr = authors.NewRow();

               // Add data to the LName column (column 0 in the row).
               dr[0] = "Author " + i.ToString();

               // Insert the row into the authors table.   
               authors.Rows.Add(dr);
            }
  
            // Create the titles table with a single column.
            DataTable titles = new DataTable("Titles");            
            titles.Columns.Add(new DataColumn("BookTitle", typeof(string)));                    
 
            // Add the titles table to the data set.
            ds.Tables.Add(titles);

            // Create sample data in the titles table.
            for (int i = 0; i < 9; i++) 
            {
               // Create a new row for the titles table.
               dr = titles.NewRow();

               // Add data to the BookTitle column (column 0 in the row).
               dr[0] = "Title " + i.ToString();

              // Insert the row into the titles table.   
              titles.Rows.Add(dr);
            }

            // Bind the HtmlSelect control to the data source.
            Select1.DataSource = ds;
            Select1.DataMember = "Titles";
            Select1.DataTextField = "BookTitle";
            Select1.DataBind();

         }

      }

      void Button_Click (Object sender, EventArgs e)
      {
       
         // Display the selected items. 
         Label1.Text = "You selected:";

         for (int i=0; i<=Select1.Items.Count - 1; i++)
         {
            if (Select1.Items[i].Selected)
               Label1.Text += "<br />    - " + Select1.Items[i].Text;
         }

      }

   </script>

</head>

<body>

   <form id="form1" runat="server">

      <h3> HtmlSelect Example </h3>

      Select items from the list. <br />
      Use the Control or Shift key to select multiple items. <br /><br />

      <select id="Select1"
              multiple="true" 
              runat="server"/>

      <br /><br />

      <button id="Button1"
              onserverclick="Button_Click"
              runat="server">

         Submit

      </button>

      <br /><br />

      <asp:Label id="Label1"
           runat="server"/>

   </form>

</body>

</html>
<%@ Page Language="VB" AutoEventWireup="True" %>
<%@ Import Namespace="System.Data" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >

<head>
    <title> HtmlSelect Example </title>
<script runat="server">

      Sub Page_Load (sender As Object, e As EventArgs)

         ' Bind the HtmlSelect control to a data source when the page is initially loaded.
         If Not IsPostBack Then
 
            Dim i As Integer
      
            ' Create a data set to store the tables.
            Dim ds As DataSet = New DataSet("TitleDataSet")
            Dim dr As DataRow 

            ' Create the authors table with a single column.
            Dim authors As DataTable = New DataTable("Authors")            
            authors.Columns.Add(New DataColumn("LName", GetType(String)))                    
 
            ' Add the authors table to the data set.
            ds.Tables.Add(authors)

            ' Create sample data in the authors table.
            For i = 0 To 9 
           
               ' Create a new row for the authors table.
               dr = authors.NewRow()

               ' Add data to the LName column (column 0 in the row).
               dr(0) = "Author " & i.ToString()

               ' Insert the row into the authors table.   
               authors.Rows.Add(dr)

            Next i
  
            ' Create the titles table with a single column.
            Dim titles As DataTable = New DataTable("Titles")            
            titles.Columns.Add(New DataColumn("BookTitle", GetType(String)))                    
 
            ' Add the titles table to the data set.
            ds.Tables.Add(titles)

            ' Create sample data in the titles table.
            For i = 0 To 9
            
               ' Create a new row for the titles table.
               dr = titles.NewRow()

               ' Add data to the BookTitle column (column 0 in the row).
               dr(0) = "Title " & i.ToString()

               ' Insert the row into the titles table.   
               titles.Rows.Add(dr)

            Next i

            ' Bind the HtmlSelect control to the data source.
            Select1.DataSource = ds
            Select1.DataMember = "Titles"
            Select1.DataTextField = "BookTitle"
            Select1.DataBind()

         End If

      End Sub

      Sub Button_Click (sender As Object, e As EventArgs)

         Dim i As Integer
       
         ' Display the selected items. 
         Label1.Text = "You selected:"

         For i=0 To Select1.Items.Count - 1
      
            If Select1.Items(i).Selected Then
               Label1.Text = Label1.Text & "<br />    - " & Select1.Items(i).Text
            End If
         
         Next i

      End Sub

   </script>

</head>

<body>

   <form id="form1" runat="server">

      <h3> HtmlSelect Example </h3>

      Select items from the list. <br />
      Use the Control or Shift key to select multiple items. <br /><br />

      <select id="Select1"
              multiple="true" 
              runat="server"/>

      <br /><br />

      <button id="Button1"
              onserverclick="Button_Click"
              runat="server">

         Submit

      </button>

      <br /><br />

      <asp:Label id="Label1"
           runat="server"/>

   </form>

</body>

</html>

Commenti

Se la DataSource proprietà contiene più set di dati, utilizzare la DataMember proprietà per specificare il set di dati da associare al controllo. Ad esempio, se si dispone di un System.Data.DataSet oggetto con più tabelle, utilizzare questa proprietà per indicare la tabella da associare al controllo.

Dopo aver specificato l'origine dati da associare al controllo, è possibile specificare i campi dell'origine dati da associare alle ListItem.Text proprietà e ListItem.Value di ogni elemento del controllo impostando rispettivamente le DataTextField proprietà e DataValueField .

Si applica a

Vedi anche