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DataGridColumnCollection.Count Propiedad

Definición

Obtiene el número de columnas de la colección DataGridColumnCollection.

public:
 property int Count { int get(); };
[System.ComponentModel.Browsable(false)]
public int Count { get; }
[<System.ComponentModel.Browsable(false)>]
member this.Count : int
Public ReadOnly Property Count As Integer

Valor de propiedad

Int32

El número de columnas de DataGridColumnCollection.

Implementaciones

Atributos

Ejemplos

En el ejemplo de código siguiente se muestra cómo usar la Count propiedad para determinar el límite superior de la DataGridColumnCollection colección. A continuación, este valor se usa para iterar la colección.

<%@ Page Language="C#" 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" >
<script language="C#" runat="server">

   DataTable Cart = new DataTable();
   DataView CartView;   

   void Page_Load(Object sender, EventArgs e) 
   {
      DataRow dr;

      if (Session["ShoppingCart"] == null) 
      {       

         Cart.Columns.Add(new DataColumn("Qty", typeof(String)));
         Cart.Columns.Add(new DataColumn("Item", typeof(String)));
         Cart.Columns.Add(new DataColumn("Price", typeof(String)));
         Session["ShoppingCart"] = Cart;
            
         // Create sample data.
         for (int i = 1; i <= 4; i++) 
         {
            dr = Cart.NewRow();
            if (i % 2 != 0)
               dr[0] = "2";
            else
               dr[0] = "1";
            dr[1] = "Item " + i.ToString();
            dr[2] = (1.23 * (i + 1)).ToString();
            Cart.Rows.Add(dr);
         }
      }
      else
         Cart = (DataTable)Session["ShoppingCart"];          

      CartView = new DataView(Cart);
      CartView.Sort="Item";

      if (!IsPostBack)
         BindGrid(); 
                  
   }

   void MyDataGrid_Edit(Object sender, DataGridCommandEventArgs e) 
   {
      MyDataGrid.EditItemIndex = e.Item.ItemIndex;
      BindGrid();
   }

   void MyDataGrid_Cancel(Object sender, DataGridCommandEventArgs e) 
   {
      MyDataGrid.EditItemIndex = -1;
      BindGrid();
   }

   void MyDataGrid_Update(Object sender, DataGridCommandEventArgs e) 
   {
      // For bound columns, the edited value is stored in a TextBox.
      // The TextBox is the 0th element in the column's cell.
      TextBox qtyText = (TextBox)e.Item.Cells[2].Controls[0];
      TextBox priceText = (TextBox)e.Item.Cells[3].Controls[0];

      String item = e.Item.Cells[1].Text;
      String qty = qtyText.Text;
      String price = priceText.Text;
       
      DataRow dr;

      // With a database, use an update command to update the data. Because 
      // the data source in this example is an in-memory DataTable, delete the 
      // old row and replace it with a new one.

      // Remove old entry.
      CartView.RowFilter = "Item='" + item + "'";
      if (CartView.Count > 0)
         CartView.Delete(0);
      CartView.RowFilter = "";

      // Add new entry.
      dr = Cart.NewRow();
      dr[0] = qty;
      dr[1] = item;
      dr[2] = price;
      Cart.Rows.Add(dr);

      MyDataGrid.EditItemIndex = -1;
      BindGrid();
   }

   void Button_Click(Object sender, EventArgs e) 
   {      
      Label1.Text = "Header Text for each column: <br />";

      for (int i = 0; i < MyDataGrid.Columns.Count; i++)
      {
         Label1.Text += "<br />" + MyDataGrid.Columns[i].HeaderText;
      }
   }

   void BindGrid() 
   {
      MyDataGrid.DataSource = CartView;
      MyDataGrid.DataBind();
   }

</script>

<head runat="server">
    <title>ASP.NET Example</title>
</head>
<body style="font: 10pt verdana">

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

      <asp:DataGrid id="MyDataGrid" runat="server"
           BorderColor="black"
           BorderWidth="1"
           CellPadding="3"
           Font-Names="Verdana"
           Font-Size="8pt"
           HeaderStyle-BackColor="#aaaadd"
           OnEditCommand="MyDataGrid_Edit"
           OnCancelCommand="MyDataGrid_Cancel"
           OnUpdateCommand="MyDataGrid_Update"
           AutoGenerateColumns="false">

         <Columns>

            <asp:EditCommandColumn
                 EditText="Edit"
                 CancelText="Cancel"
                 UpdateText="Update"
                 ItemStyle-Wrap="false"
                 HeaderText="Edit Command Column"
                 HeaderStyle-Wrap="false"/>

            <asp:BoundColumn HeaderText="Item" 
                 ReadOnly="true" 
                 DataField="Item"/>

            <asp:BoundColumn HeaderText="Quantity" 
                 DataField="Qty"/>

            <asp:BoundColumn HeaderText="Price" 
                 DataField="Price"/>

         </Columns>

      </asp:DataGrid>

      <br /><br />

      <asp:Button id="Button1"
           Text="Display Header Text for Columns"
           OnClick="Button_Click"
           runat="server"/>

      <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" >
<script language="VB" runat="server">

    Dim Cart As New DataTable()
    Dim CartView As DataView

    Sub Page_Load(sender As Object, e As EventArgs)
        Dim dr As DataRow
        
        If Session("ShoppingCart") Is Nothing Then
            
            Cart.Columns.Add(New DataColumn("Qty", GetType(String)))
            Cart.Columns.Add(New DataColumn("Item", GetType(String)))
            Cart.Columns.Add(New DataColumn("Price", GetType(String)))
            Session("ShoppingCart") = Cart
            
            ' Create sample data.
            Dim i As Integer
            For i = 1 To 4
                dr = Cart.NewRow()
                If i Mod 2 <> 0 Then
                    dr(0) = "2"
                Else
                    dr(0) = "1"
                End If
                dr(1) = "Item " & i.ToString()
                dr(2) =(1.23 *(i + 1)).ToString()
                Cart.Rows.Add(dr)
            Next i
        Else
            Cart = CType(Session("ShoppingCart"), DataTable)
        End If 
        CartView = New DataView(Cart)
        CartView.Sort = "Item"
        
        If Not IsPostBack Then
            BindGrid()
        End If 
    End Sub 'Page_Load


    Sub MyDataGrid_Edit(sender As Object, e As DataGridCommandEventArgs)
        MyDataGrid.EditItemIndex = e.Item.ItemIndex
        BindGrid()
    End Sub 'MyDataGrid_Edit


    Sub MyDataGrid_Cancel(sender As Object, e As DataGridCommandEventArgs)
        MyDataGrid.EditItemIndex = - 1
        BindGrid()
    End Sub 'MyDataGrid_Cancel


    Sub MyDataGrid_Update(sender As Object, e As DataGridCommandEventArgs)
        ' For bound columns, the edited value is stored in a TextBox.
        ' The TextBox is the 0th element in the column's cell.
        Dim qtyText As TextBox = CType(e.Item.Cells(2).Controls(0), TextBox)
        Dim priceText As TextBox = CType(e.Item.Cells(3).Controls(0), TextBox)
        
        Dim item As String = e.Item.Cells(1).Text
        Dim qty As String = qtyText.Text
        Dim price As String = priceText.Text
        
        Dim dr As DataRow
        
        ' With a database, use an update command to update the data. Because 
        ' the data source in this example is an in-memory DataTable, delete the 
        ' old row and replace it with a new one.        

        ' Remove old entry.
        CartView.RowFilter = "Item='" & item & "'"
        If CartView.Count > 0 Then
            CartView.Delete(0)
        End If
        CartView.RowFilter = ""
        
        ' Add new entry.
        dr = Cart.NewRow()
        dr(0) = qty
        dr(1) = item
        dr(2) = price
        Cart.Rows.Add(dr)
        
        MyDataGrid.EditItemIndex = - 1
        BindGrid()
    End Sub 'MyDataGrid_Update


    Sub Button_Click(sender As Object, e As EventArgs)
        Label1.Text = "Header Text for each column: <br /><br />"
        
        Dim i As Integer
        For i = 0 To MyDataGrid.Columns.Count - 1
            Label1.Text &= "<br />" & MyDataGrid.Columns(i).HeaderText
        Next i
    End Sub 'Button_Click


    Sub BindGrid()
        MyDataGrid.DataSource = CartView
        MyDataGrid.DataBind()
    End Sub 'BindGrid

</script>

<head runat="server">
    <title>ASP.NET Example</title>
</head>
<body style="font: 10pt verdana">

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

      <asp:DataGrid id="MyDataGrid" runat="server"
           BorderColor="black"
           BorderWidth="1"
           CellPadding="3"
           Font-Names="Verdana"
           Font-Size="8pt"
           HeaderStyle-BackColor="#aaaadd"
           OnEditCommand="MyDataGrid_Edit"
           OnCancelCommand="MyDataGrid_Cancel"
           OnUpdateCommand="MyDataGrid_Update"
           AutoGenerateColumns="false">

         <Columns>

            <asp:EditCommandColumn
                 EditText="Edit"
                 CancelText="Cancel"
                 UpdateText="Update"
                 ItemStyle-Wrap="false"
                 HeaderText="Edit Command Column"
                 HeaderStyle-Wrap="false"/>

            <asp:BoundColumn HeaderText="Item" 
                 ReadOnly="true" 
                 DataField="Item"/>

            <asp:BoundColumn HeaderText="Quantity" 
                 DataField="Qty"/>

            <asp:BoundColumn HeaderText="Price" 
                 DataField="Price"/>

         </Columns>

      </asp:DataGrid>

      <br /><br />

      <asp:Button id="Button1"
           Text="Display Header Text for Columns"
           OnClick="Button_Click"
           runat="server"/>

      <br /><br />

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

   </form>

</body>
</html>

Comentarios

Utilice esta propiedad para determinar el número de columnas de la DataGridColumnCollection colección. La Count propiedad se usa normalmente al recorrer en iteración la colección para determinar el límite superior de la colección.

Se aplica a

Consulte también