DataGrid.Columns-Eigenschaft
Ruft eine Auflistung von Objekten ab, die die Spalten des DataGrid-Steuerelements darstellen.
Namespace: System.Web.UI.WebControls
Assembly: System.Web (in system.web.dll)
Syntax
'Declaration
Public Overridable ReadOnly Property Columns As DataGridColumnCollection
'Usage
Dim instance As DataGrid
Dim value As DataGridColumnCollection
value = instance.Columns
public virtual DataGridColumnCollection Columns { get; }
public:
virtual property DataGridColumnCollection^ Columns {
DataGridColumnCollection^ get ();
}
/** @property */
public DataGridColumnCollection get_Columns ()
public function get Columns () : DataGridColumnCollection
Eigenschaftenwert
Ein DataGridColumnCollection-Objekt, das eine Auflistung von Objekten enthält, die die Spalten des DataGrid-Steuerelements darstellen.
Hinweise
Legen Sie mit dieser Eigenschaft die Auflistung von Spalten im DataGrid-Steuerelement programmgesteuert fest. Die Columns-Auflistung enthält explizit deklarierte Spalten, die im DataGrid-Steuerelement wiedergegeben werden.
Hinweis
Explizit deklarierte Spalten können zusammen mit automatisch erstellten Spalten verwendet werden. Wenn Sie beide Spaltenarten verwenden, werden explizit deklarierte Spalten zuerst und anschließend die automatisch erstellten Spalten dargestellt. Automatisch generierte Spalten werden der Columns-Auflistung nicht hinzugefügt.
Die Reihenfolge, in der die Spalten im DataGrid-Steuerelement angezeigt werden, wird durch die Reihenfolge bestimmt, in der die Spalten in der Columns-Auflistung aufgeführt sind.
In der folgenden Tabelle werden die unterschiedlichen Spaltenklassen aufgeführt, die von der DataGridColumn-Klasse abgeleitet sind und in der Columns-Auflistung verwendet werden können.
Spaltentyp |
Beschreibung |
|---|---|
Zeigt eine Spalte an, die an ein Feld in einer Datenquelle gebunden ist. Jedes Element in diesem Feld wird als Text angezeigt. Dies ist der Standardspaltentyp des DataGrid-Steuerelements. |
|
Zeigt eine Befehlsschaltfläche für jedes Element in der Spalte an. Damit können Sie eine Spalte mit benutzerdefinierten Schaltflächensteuerelementen erstellen, z. B. die Schaltflächen Add und Remove. |
|
Zeigt eine Spalte an, die Bearbeitungsbefehle für jedes Element in der Spalte enthält. |
|
Zeigt den Inhalt der einzelnen Elemente in der Spalte als Hyperlink an. Der Inhalt der Spalte kann an ein Feld in einer Datenquelle oder an statischen Text gebunden werden. |
|
Zeigt jedes Element in der Spalte entsprechend einer angegebenen Vorlage an. Dadurch können Sie benutzerdefinierte Steuerelemente in der Spalte bereitstellen. |
Hinweis
Obwohl Sie der Columns-Auflistung programmgesteuert Spalten hinzufügen können, ist es einfacher, die Spalten statisch aufzulisten und die gewünschte Spalte anschließend mit der Visible-Eigenschaft anzuzeigen oder auszublenden.
Beispiel
Das folgende Codebeispiel veranschaulicht die Verwendung der Columns-Auflistung zum dynamischen Hinzufügen einer Spalte zum DataGrid-Steuerelement.
<%@ Page Language="VB" AutoEventWireup="True" %>
<%@ Import Namespace="System.Data" %>
<html>
<script language="VB" runat="server">
Dim Cart As DataTable
Dim CartView As DataView
Function CreateDataSource() As ICollection
Dim dt As New DataTable()
Dim dr As DataRow
dt.Columns.Add(New DataColumn("IntegerValue", GetType(Int32)))
dt.Columns.Add(New DataColumn("StringValue", GetType(String)))
dt.Columns.Add(New DataColumn("CurrencyValue", GetType(Double)))
Dim i As Integer
For i = 0 To 8
dr = dt.NewRow()
dr(0) = i
dr(1) = "Item " & i.ToString()
dr(2) = 1.23 *(i + 1)
dt.Rows.Add(dr)
Next i
Dim dv As New DataView(dt)
Return dv
End Function 'CreateDataSource
Sub Page_Load(sender As Object, e As EventArgs)
If Session("DG4_ShoppingCart") Is Nothing Then
Cart = New DataTable()
Cart.Columns.Add(New DataColumn("Item", GetType(String)))
Cart.Columns.Add(New DataColumn("Price", GetType(String)))
Session("DG4_ShoppingCart") = Cart
Else
Cart = CType(Session("DG4_ShoppingCart"), DataTable)
End If
CartView = New DataView(Cart)
ShoppingCart.DataSource = CartView
ShoppingCart.DataBind()
If Not IsPostBack Then
' Load this data only once.
ItemsGrid.DataSource = CreateDataSource()
ItemsGrid.DataBind()
End If
End Sub 'Page_Load
Sub Page_Init(sender As Object, e As EventArgs)
' Create a dynamic column to add to Columns collection.
Dim NumberColumn As New BoundColumn()
NumberColumn.HeaderText = "Item Number"
NumberColumn.DataField = "IntegerValue"
' Add column to Columns collection.
ItemsGrid.Columns.AddAt(2, NumberColumn)
End Sub 'Page_Init
Sub Grid_CartCommand(sender As Object, e As DataGridCommandEventArgs)
Dim dr As DataRow = Cart.NewRow()
' e.Item is the table row where the command is raised.
' For bound columns, the value is stored in the Text property of the TableCell.
Dim itemCell As TableCell = e.Item.Cells(2)
Dim priceCell As TableCell = e.Item.Cells(3)
Dim item As String = itemCell.Text
Dim price As String = priceCell.Text
If CType(e.CommandSource, Button).CommandName = "AddToCart" Then
dr(0) = item
dr(1) = price
Cart.Rows.Add(dr)
Else
'Remove from Cart.
CartView.RowFilter = "Item='" & item & "'"
If CartView.Count > 0 Then
CartView.Delete(0)
End If
CartView.RowFilter = ""
End If
ShoppingCart.DataBind()
End Sub 'Grid_CartCommand
</script>
<body>
<form runat=server>
<h3>DataGrid Columns Example</h3>
<table cellpadding="5">
<tr valign="top">
<td>
<b>Product List</b>
<asp:DataGrid id="ItemsGrid"
BorderColor="black"
BorderWidth="1"
CellPadding="3"
AutoGenerateColumns="false"
OnItemCommand="Grid_CartCommand"
runat="server">
<HeaderStyle BackColor="#00aaaa">
</HeaderStyle>
<Columns>
<asp:ButtonColumn
HeaderText="Add to cart"
ButtonType="PushButton"
Text="Add"
CommandName="AddToCart"/>
<asp:ButtonColumn
HeaderText="Remove from cart"
ButtonType="PushButton"
Text="Remove"
CommandName="RemoveFromCart"/>
<asp:BoundColumn
HeaderText="Item"
DataField="StringValue"/>
<asp:BoundColumn
HeaderText="Price"
DataField="CurrencyValue"
DataFormatString="{0:c}">
<ItemStyle HorizontalAlign="right">
</ItemStyle>
</asp:BoundColumn>
</Columns>
</asp:DataGrid>
</td>
<td>
<b>Shopping Cart</b>
<asp:DataGrid id="ShoppingCart"
runat="server"
BorderColor="black"
BorderWidth="1"
GridLines="Both"
ShowFooter="false"
CellPadding="3"
CellSpacing="0">
<HeaderStyle BackColor="#00aaaa">
</HeaderStyle>
</asp:DataGrid>
</td>
</tr>
</table>
</form>
</body>
</html>
<%@ Page Language="C#" AutoEventWireup="True" %>
<%@ Import Namespace="System.Data" %>
<html>
<script language="C#" runat="server">
DataTable Cart;
DataView CartView;
ICollection CreateDataSource()
{
DataTable dt = new DataTable();
DataRow dr;
dt.Columns.Add(new DataColumn("IntegerValue", typeof(Int32)));
dt.Columns.Add(new DataColumn("StringValue", typeof(string)));
dt.Columns.Add(new DataColumn("CurrencyValue", typeof(double)));
for (int i = 0; i < 9; i++)
{
dr = dt.NewRow();
dr[0] = i;
dr[1] = "Item " + i.ToString();
dr[2] = 1.23 * (i + 1);
dt.Rows.Add(dr);
}
DataView dv = new DataView(dt);
return dv;
}
void Page_Load(Object sender, EventArgs e)
{
if (Session["DG4_ShoppingCart"] == null)
{
Cart = new DataTable();
Cart.Columns.Add(new DataColumn("Item", typeof(string)));
Cart.Columns.Add(new DataColumn("Price", typeof(string)));
Session["DG4_ShoppingCart"] = Cart;
}
else
{
Cart = (DataTable)Session["DG4_ShoppingCart"];
}
CartView = new DataView(Cart);
ShoppingCart.DataSource = CartView;
ShoppingCart.DataBind();
if (!IsPostBack)
{
// Load this data only once.
ItemsGrid.DataSource= CreateDataSource();
ItemsGrid.DataBind();
}
}
void Page_Init(Object sender, EventArgs e)
{
// Create a dynamic column to add to Columns collection.
BoundColumn NumberColumn = new BoundColumn();
NumberColumn.HeaderText="Item Number";
NumberColumn.DataField="IntegerValue";
// Add column to Columns collection.
ItemsGrid.Columns.AddAt(2, NumberColumn);
}
void Grid_CartCommand(Object sender, DataGridCommandEventArgs e) {
DataRow dr = Cart.NewRow();
// e.Item is the table row where the command is raised.
// For bound columns, the value is stored in the Text property of the TableCell.
TableCell itemCell = e.Item.Cells[2];
TableCell priceCell = e.Item.Cells[3];
string item = itemCell.Text;
string price = priceCell.Text;
if (((Button)e.CommandSource).CommandName == "AddToCart")
{
dr[0] = item;
dr[1] = price;
Cart.Rows.Add(dr);
}
else
{
//Remove from Cart.
CartView.RowFilter = "Item='" + item + "'";
if (CartView.Count > 0)
{
CartView.Delete(0);
}
CartView.RowFilter = "";
}
ShoppingCart.DataBind();
}
</script>
<body>
<form runat=server>
<h3>DataGrid Columns Example</h3>
<table cellpadding="5">
<tr valign="top">
<td>
<b>Product List</b>
<asp:DataGrid id="ItemsGrid"
BorderColor="black"
BorderWidth="1"
CellPadding="3"
AutoGenerateColumns="false"
OnItemCommand="Grid_CartCommand"
runat="server">
<HeaderStyle BackColor="#00aaaa">
</HeaderStyle>
<Columns>
<asp:ButtonColumn
HeaderText="Add to cart"
ButtonType="PushButton"
Text="Add"
CommandName="AddToCart"/>
<asp:ButtonColumn
HeaderText="Remove from cart"
ButtonType="PushButton"
Text="Remove"
CommandName="RemoveFromCart"/>
<asp:BoundColumn
HeaderText="Item"
DataField="StringValue"/>
<asp:BoundColumn
HeaderText="Price"
DataField="CurrencyValue"
DataFormatString="{0:c}">
<ItemStyle HorizontalAlign="right">
</ItemStyle>
</asp:BoundColumn>
</Columns>
</asp:DataGrid>
</td>
<td>
<b>Shopping Cart</b>
<asp:DataGrid id="ShoppingCart"
runat="server"
BorderColor="black"
BorderWidth="1"
GridLines="Both"
ShowFooter="false"
CellPadding="3"
CellSpacing="0">
<HeaderStyle BackColor="#00aaaa">
</HeaderStyle>
</asp:DataGrid>
</td>
</tr>
</table>
</form>
</body>
</html>
<%@ Page Language="JScript" AutoEventWireup="True" %>
<%@ Import Namespace="System.Data" %>
<html>
<script language="JScript" runat="server">
var Cart : DataTable = new DataTable();
var CartView : DataView;
function CreateDataSource() : ICollection
{
var dt : DataTable = new DataTable();
var dr : DataRow;
dt.Columns.Add(new DataColumn("IntegerValue", Int32));
dt.Columns.Add(new DataColumn("StringValue", System.String));
dt.Columns.Add(new DataColumn("CurrencyValue", double));
for (var i : int = 0; i < 9; i++)
{
dr = dt.NewRow();
dr[0] = i;
dr[1] = "Item " + i.ToString();
dr[2] = 1.23 * (i + 1);
dt.Rows.Add(dr);
}
var dv : DataView = new DataView(dt);
return dv;
}
function Page_Load(sender, e : EventArgs)
{
if (Session["DG4_ShoppingCart"] == null)
{
Cart = new DataTable();
Cart.Columns.Add(new DataColumn("Item", System.String));
Cart.Columns.Add(new DataColumn("Price", System.String));
Session["DG4_ShoppingCart"] = Cart;
}
else
{
Cart = DataTable(Session["DG4_ShoppingCart"]);
}
CartView = new DataView(Cart);
ShoppingCart.DataSource = CartView;
ShoppingCart.DataBind();
if (!IsPostBack)
{
// Load this data only once.
ItemsGrid.DataSource= CreateDataSource();
ItemsGrid.DataBind();
}
}
function Page_Init(sender, e : EventArgs)
{
// Create a dynamic column to add to Columns collection.
var NumberColumn : BoundColumn = new BoundColumn();
NumberColumn.HeaderText="Item Number";
NumberColumn.DataField="IntegerValue";
// Add column to Columns collection.
ItemsGrid.Columns.AddAt(2, NumberColumn);
}
function Grid_CartCommand(sender, e : DataGridCommandEventArgs) {
var dr : DataRow = Cart.NewRow();
// e.Item is the table row where the command is raised.
// For bound columns, the value is stored in the Text property of the TableCell.
var itemCell : TableCell = e.Item.Cells[2];
var priceCell : TableCell = e.Item.Cells[3];
var item : String = itemCell.Text;
var price : String = priceCell.Text;
if ((Button(e.CommandSource)).CommandName == "AddToCart")
{
dr[0] = item;
dr[1] = price;
Cart.Rows.Add(dr);
}
else
{
//Remove from Cart.
CartView.RowFilter = "Item='" + item + "'";
if (CartView.Count > 0)
{
CartView.Delete(0);
}
CartView.RowFilter = "";
}
ShoppingCart.DataBind();
}
</script>
<body>
<form runat=server>
<h3>DataGrid Columns Example</h3>
<table cellpadding="5">
<tr valign="top">
<td>
<b>Product List</b>
<asp:DataGrid id="ItemsGrid"
BorderColor="black"
BorderWidth="1"
CellPadding="3"
AutoGenerateColumns="false"
OnItemCommand="Grid_CartCommand"
runat="server">
<HeaderStyle BackColor="#00aaaa">
</HeaderStyle>
<Columns>
<asp:ButtonColumn
HeaderText="Add to cart"
ButtonType="PushButton"
Text="Add"
CommandName="AddToCart"/>
<asp:ButtonColumn
HeaderText="Remove from cart"
ButtonType="PushButton"
Text="Remove"
CommandName="RemoveFromCart"/>
<asp:BoundColumn
HeaderText="Item"
DataField="StringValue"/>
<asp:BoundColumn
HeaderText="Price"
DataField="CurrencyValue"
DataFormatString="{0:c}">
<ItemStyle HorizontalAlign="right">
</ItemStyle>
</asp:BoundColumn>
</Columns>
</asp:DataGrid>
</td>
<td>
<b>Shopping Cart</b>
<asp:DataGrid id="ShoppingCart"
runat="server"
BorderColor="black"
BorderWidth="1"
GridLines="Both"
ShowFooter="false"
CellPadding="3"
CellSpacing="0">
<HeaderStyle BackColor="#00aaaa">
</HeaderStyle>
</asp:DataGrid>
</td>
</tr>
</table>
</form>
</body>
</html>
<%@ Page Language="VB" AutoEventWireup="True" %>
<%@ Import Namespace="System.Data" %>
<html>
<script runat="server">
Function CreateDataSource() As ICollection
' Create sample data for the DataGrid control.
Dim dt As DataTable = New DataTable()
Dim dr As DataRow
' Define the columns of the table.
dt.Columns.Add(New DataColumn("IntegerValue", GetType(Int32)))
dt.Columns.Add(New DataColumn("StringValue", GetType(string)))
dt.Columns.Add(New DataColumn("CurrencyValue", GetType(double)))
' Populate the table with sample values.
Dim i As Integer
For i = 0 to 4
dr = dt.NewRow()
dr(0) = i
dr(1) = "Item " & i.ToString()
dr(2) = 1.23 * (i + 1)
dt.Rows.Add(dr)
Next i
Dim dv As DataView = New DataView(dt)
Return dv
End Function
Sub Page_Load(sender As Object, e As EventArgs)
' Load sample data only once, when the page is first loaded.
If Not IsPostBack Then
ItemsGrid.DataSource = CreateDataSource()
ItemsGrid.DataBind()
End If
End Sub
Sub Button_Click(sender As Object, e As EventArgs)
' Count the number of selected items in the DataGrid control.
Dim count As Integer = 0
' Display the selected times.
Message.Text = "You Selected: <br>"
' Iterate through each item (row) in the DataGrid control and
' determine whether it is selected.
Dim item As DataGridItem
For Each item In ItemsGrid.Items
DetermineSelection(item, count)
Next
' If no items are selected, display the appropriate message.
If count = 0 Then
Message.Text = "No items selected"
End If
End Sub
Sub DetermineSelection(item As DataGridItem, ByRef count As Integer)
' Retrieve the SelectCheckBox CheckBox control from the
' specified item (row) in the DataGrid control.
Dim selection As CheckBox = _
CType(item.FindControl("SelectCheckBox"), CheckBox)
' If the item is selected, display the appropriate message and
' increment the count of selected items.
If Not selection Is Nothing Then
If selection.Checked Then
Message.Text &= "- " & item.Cells(1).Text & "<br>"
count = count + 1
End If
End If
End Sub
Sub Check_Change(sender As Object, e As EventArgs)
' Show or hide the first column depending on the value of
' the check box.
If ShowCheckBox.Checked Then
ItemsGrid.Columns(0).Visible = True
Else
ItemsGrid.Columns(0).Visible = False
End If
End Sub
</script>
<body>
<form runat=server>
<h3>DataGridColumn Visible Example</h3>
Select whether to show or hide the first column.
<br><br>
<b>Product List</b>
<asp:DataGrid id="ItemsGrid"
BorderColor="black"
BorderWidth="1"
CellPadding="3"
ShowFooter="True"
AutoGenerateColumns="False"
runat="server">
<HeaderStyle BackColor="#00aaaa">
</HeaderStyle>
<FooterStyle BackColor="#00aaaa">
</FooterStyle>
<Columns>
<asp:BoundColumn DataField="IntegerValue"
Visible="True"
HeaderText="Item"/>
<asp:BoundColumn DataField="StringValue"
Visible="True"
HeaderText="Description"/>
<asp:BoundColumn DataField="CurrencyValue"
Visible="True"
HeaderText="Price"
DataFormatString="{0:c}">
<ItemStyle HorizontalAlign="Right">
</ItemStyle>
</asp:BoundColumn>
<asp:TemplateColumn HeaderText="Select Item"
Visible="True" >
<ItemTemplate>
<asp:CheckBox id="SelectCheckBox"
Text="Add to Cart"
Checked="False"
runat="server"/>
</ItemTemplate>
</asp:TemplateColumn>
</Columns>
</asp:DataGrid>
<br><br>
<asp:Button id="SubmitButton"
Text="Submit"
OnClick = "Button_Click"
runat="server"/>
<br><br>
<asp:Label id="Message"
runat="server"/>
<hr>
<asp:CheckBox id="ShowCheckBox"
Text="Show first column"
AutoPostBack="True"
OnCheckedChanged="Check_Change"
Checked="True"
runat="server"/>
</form>
</body>
</html>
<%@ Page Language="C#" AutoEventWireup="True" %>
<%@ Import Namespace="System.Data" %>
<html>
<script runat="server">
ICollection CreateDataSource()
{
// Create sample data for the DataGrid control.
DataTable dt = new DataTable();
DataRow dr;
// Define the columns of the table.
dt.Columns.Add(new DataColumn("IntegerValue", typeof(Int32)));
dt.Columns.Add(new DataColumn("StringValue", typeof(string)));
dt.Columns.Add(new DataColumn("CurrencyValue", typeof(double)));
// Populate the table with sample values.
for (int i = 0; i < 5; i++)
{
dr = dt.NewRow();
dr[0] = i;
dr[1] = "Item " + i.ToString();
dr[2] = 1.23 * (i + 1);
dt.Rows.Add(dr);
}
DataView dv = new DataView(dt);
return dv;
}
void Page_Load(Object sender, EventArgs e)
{
// Load sample data only once, when the page is first loaded.
if (!IsPostBack)
{
ItemsGrid.DataSource = CreateDataSource();
ItemsGrid.DataBind();
}
}
void Button_Click(Object sender, EventArgs e)
{
// Count the number of selected items in the DataGrid control.
int count = 0;
// Display the selected times.
Message.Text = "You Selected: <br>";
// Iterate through each item (row) in the DataGrid control and
// determine whether it is selected.
foreach (DataGridItem item in ItemsGrid.Items)
{
DetermineSelection(item, ref count);
}
// If no items are selected, display the appropriate message.
if (count == 0)
{
Message.Text = "No items selected";
}
}
void DetermineSelection(DataGridItem item, ref int count)
{
// Retrieve the SelectCheckBox CheckBox control from the
// specified item (row) in the DataGrid control.
CheckBox selection = (CheckBox)item.FindControl("SelectCheckBox");
// If the item is selected, display the appropriate message and
// increment the count of selected items.
if (selection != null)
{
if (selection.Checked)
{
Message.Text += "- " + item.Cells[1].Text + "<br>";
count++;
}
}
}
void Check_Change(Object sender, EventArgs e)
{
// Show or hide the first column depending on the value of
// the check box.
if (ShowCheckBox.Checked)
{
ItemsGrid.Columns[0].Visible = true;
}
else
{
ItemsGrid.Columns[0].Visible = false;
}
}
</script>
<body>
<form runat=server>
<h3>DataGridColumn Visible Example</h3>
Select whether to show or hide the first column.
<br><br>
<b>Product List</b>
<asp:DataGrid id="ItemsGrid"
BorderColor="black"
BorderWidth="1"
CellPadding="3"
ShowFooter="True"
AutoGenerateColumns="False"
runat="server">
<HeaderStyle BackColor="#00aaaa">
</HeaderStyle>
<FooterStyle BackColor="#00aaaa">
</FooterStyle>
<Columns>
<asp:BoundColumn DataField="IntegerValue"
Visible="True"
HeaderText="Item"/>
<asp:BoundColumn DataField="StringValue"
Visible="True"
HeaderText="Description"/>
<asp:BoundColumn DataField="CurrencyValue"
Visible="True"
HeaderText="Price"
DataFormatString="{0:c}">
<ItemStyle HorizontalAlign="Right">
</ItemStyle>
</asp:BoundColumn>
<asp:TemplateColumn HeaderText="Select Item"
Visible="True" >
<ItemTemplate>
<asp:CheckBox id="SelectCheckBox"
Text="Add to Cart"
Checked="False"
runat="server"/>
</ItemTemplate>
</asp:TemplateColumn>
</Columns>
</asp:DataGrid>
<br><br>
<asp:Button id="SubmitButton"
Text="Submit"
OnClick = "Button_Click"
runat="server"/>
<br><br>
<asp:Label id="Message"
runat="server"/>
<hr>
<asp:CheckBox id="ShowCheckBox"
Text="Show first column"
AutoPostBack="True"
OnCheckedChanged="Check_Change"
Checked="True"
runat="server"/>
</form>
</body>
</html>
Plattformen
Windows 98, Windows 2000 SP4, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
.NET Framework unterstützt nicht alle Versionen sämtlicher Plattformen. Eine Liste der unterstützten Versionen finden Sie unter Systemanforderungen.
Versionsinformationen
.NET Framework
Unterstützt in: 2.0, 1.1, 1.0
Siehe auch
Referenz
DataGrid-Klasse
DataGrid-Member
System.Web.UI.WebControls-Namespace
DataGridColumn
BoundColumn-Klasse
ButtonColumn-Klasse
EditCommandColumn
HyperLinkColumn
TemplateColumn