DataGrid.AllowSorting Vlastnost
Definice
Důležité
Některé informace platí pro předběžně vydaný produkt, který se může zásadně změnit, než ho výrobce nebo autor vydá. Microsoft neposkytuje žádné záruky, výslovné ani předpokládané, týkající se zde uváděných informací.
Získá nebo nastaví hodnotu, která označuje, zda je povoleno řazení.
public:
virtual property bool AllowSorting { bool get(); void set(bool value); };
public virtual bool AllowSorting { get; set; }
member this.AllowSorting : bool with get, set
Public Overridable Property AllowSorting As Boolean
Hodnota vlastnosti
true
pokud je povoleno řazení; v opačném případě . false
Výchozí hodnota je false
.
Příklady
Následující příklad kódu ukazuje, jak použít AllowSorting vlastnost k povolení řazení.
<%@ 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">
string SortExpression;
ICollection CreateDataSource()
{
DataTable dt = new DataTable();
DataRow dr;
Random Rand_Num = new Random();
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 < 15; i++)
{
dr = dt.NewRow();
dr[0] = i;
dr[1] = "Item " + i.ToString();
dr[2] = 1.23 * Rand_Num.Next(1, 15);
dt.Rows.Add(dr);
}
DataView dv = new DataView(dt);
dv.Sort=SortExpression;
return dv;
}
void Page_Load(Object sender, EventArgs e)
{
if (!IsPostBack)
{
if (SortExpression == "")
SortExpression = "IntegerValue";
ItemsGrid.DataSource = CreateDataSource();
ItemsGrid.DataBind();
}
}
void Sort_Grid(Object sender, DataGridSortCommandEventArgs e)
{
SortExpression = e.SortExpression.ToString();
ItemsGrid.DataSource = CreateDataSource();
ItemsGrid.DataBind();
}
</script>
<head runat="server">
<title>DataGrid Sorting Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>DataGrid Sorting Example</h3>
<asp:DataGrid id="ItemsGrid" runat="server"
BorderColor="black"
BorderWidth="1"
CellPadding="3"
AllowSorting="true"
OnSortCommand="Sort_Grid"
HeaderStyle-BackColor="#00aaaa"
AutoGenerateColumns="true"/>
</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 SortExpression As String
Function CreateDataSource() As ICollection
Dim dt As New DataTable()
Dim dr As DataRow
Dim Rand_Num As New Random()
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 14
dr = dt.NewRow()
dr(0) = i
dr(1) = "Item " & i.ToString()
dr(2) = 1.23 * Rand_Num.Next(1, 15)
dt.Rows.Add(dr)
Next i
Dim dv As New DataView(dt)
dv.Sort = SortExpression
Return dv
End Function 'CreateDataSource
Sub Page_Load(sender As Object, e As EventArgs)
If Not IsPostBack Then
If SortExpression = "" Then
SortExpression = "IntegerValue"
End If
ItemsGrid.DataSource = CreateDataSource()
ItemsGrid.DataBind()
End If
End Sub 'Page_Load
Sub Sort_Grid(sender As Object, e As DataGridSortCommandEventArgs)
SortExpression = e.SortExpression.ToString()
ItemsGrid.DataSource = CreateDataSource()
ItemsGrid.DataBind()
End Sub 'Sort_Grid
</script>
<head runat="server">
<title>DataGrid Sorting Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>DataGrid Sorting Example</h3>
<asp:DataGrid id="ItemsGrid" runat="server"
BorderColor="black"
BorderWidth="1"
CellPadding="3"
AllowSorting="true"
OnSortCommand="Sort_Grid"
HeaderStyle-BackColor="#00aaaa"
AutoGenerateColumns="true"/>
</form>
</body>
</html>
<%@ 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">
<script runat="server">
ICollection CreateDataSource()
{
// Create a Random object to mix up the
// order of items in the sample data.
Random randNum = new Random();
// Create sample data for the DataGrid control.
DataTable dt = new DataTable();
// 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 <= 8; i++)
{
DataRow dr = dt.NewRow();
dr[0] = i;
dr[1] = "Item " + randNum.Next(1, 15).ToString();
dr[2] = 1.23 * randNum.Next(1, 15);
dt.Rows.Add(dr);
}
// To persist the data source between posts to the server,
// store it in session state.
Session["Source"] = dt;
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 Sort_Grid(Object sender, DataGridSortCommandEventArgs e)
{
// Retrieve the data source from session state.
DataTable dt = (DataTable)Session["Source"];
// Create a DataView from the DataTable.
DataView dv = new DataView(dt);
// The DataView provides an easy way to sort. Simply set the
// Sort property with the name of the field to sort by.
dv.Sort = e.SortExpression;
// Rebind the data source and specify that it should be sorted
// by the field specified in the SortExpression property.
ItemsGrid.DataSource = dv;
ItemsGrid.DataBind();
}
void Check_Change(Object sender, EventArgs e)
{
// Allow or prevent sorting depending on the user's selection.
ItemsGrid.AllowSorting = AllowSortingCheckBox.Checked;
// After changing the property, rebind the data to
// refresh the DataGrid control.
// Retrieve the data source from session state.
DataTable dt = (DataTable)Session["Source"];
// Create a DataView from the DataTable.
DataView dv = new DataView(dt);
// Rebind the data source.
ItemsGrid.DataSource = dv;
ItemsGrid.DataBind();
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" runat="server">
<title>
ExtractTemplateRows Example
</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<h3>DataGrid AllowSorting Example</h3>
<p>Select whether to allow sorting in the DataGrid control.<br />
<asp:CheckBox id="AllowSortingCheckBox"
Text="Allow sorting"
AutoPostBack="True"
Checked="True"
OnCheckedChanged="Check_Change"
runat="server"/></p>
<hr />
<b>Product List</b>
<asp:DataGrid id="ItemsGrid"
BorderColor="black"
BorderWidth="1"
CellPadding="3"
OnSortCommand="Sort_Grid"
UseAccessibleHeader="true"
AutoGenerateColumns="False"
AllowSorting="True"
runat="server">
<HeaderStyle BackColor="#00aaaa" />
<Columns>
<asp:BoundColumn DataField="IntegerValue"
SortExpression="IntegerValue"
HeaderText="Item"/>
<asp:BoundColumn DataField="StringValue"
SortExpression="StringValue"
HeaderText="Description"/>
<asp:BoundColumn DataField="CurrencyValue"
HeaderText="Price"
SortExpression="CurrencyValue"
DataFormatString="{0:c}">
<ItemStyle HorizontalAlign="Right">
</ItemStyle>
</asp:BoundColumn>
</Columns>
</asp:DataGrid>
</div>
</form>
</body>
</html>
<%@ Page Language="VB" %>
<%@ Import Namespace="System.Data" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
Function CreateDataSource() As ICollection
' Create a Random object to mix up the order
' of items in the sample data.
Dim randNum As Random = New Random()
' Create sample data for the DataGrid control.
Dim dt As DataTable = New DataTable()
' 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 8
Dim dr As DataRow = dt.NewRow()
dr(0) = i
dr(1) = "Item " & randNum.Next(1, 15).ToString()
dr(2) = 1.23 * randNum.Next(1, 15)
dt.Rows.Add(dr)
Next
' Persist the data source between posts to
' the server, in the session state.
Session("Source") = dt
Dim dv As DataView = New DataView(dt)
Return dv
End Function
Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)
' Load sample data when the page is first loaded.
If Not IsPostBack Then
ItemsGrid.DataSource = CreateDataSource()
ItemsGrid.DataBind()
End If
End Sub
Sub Sort_Grid(ByVal sender As Object, _
ByVal e As DataGridSortCommandEventArgs)
' Retrieve the data source from session state.
Dim dt As DataTable = _
CType(Session("Source"), DataTable)
' Create a DataView from the DataTable.
Dim dv As DataView = New DataView(dt)
' The DataView provides an easy way to
' sort. Simply set the Sort property with
' the name of the field to sort by.
dv.Sort = e.SortExpression
' Rebind the data source and specify that
' it should be sorted by the field specified
' in the SortExpression property.
ItemsGrid.DataSource = dv
ItemsGrid.DataBind()
End Sub
Sub Check_Change(ByVal sender As Object, _
ByVal e As EventArgs)
' Allow or prevent sorting depending
' on the user's selection.
ItemsGrid.AllowSorting = _
AllowSortingCheckBox.Checked
' After changing the property, rebind
' the data to refresh the DataGrid control.
' Retrieve data source from session state.
Dim dt As DataTable = _
CType(Session("Source"), DataTable)
' Create a DataView from the DataTable.
Dim dv As DataView = New DataView(dt)
' Rebind the data source.
ItemsGrid.DataSource = dv
ItemsGrid.DataBind()
End Sub
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" runat="server">
<title>
ExtractTemplateRows Example
</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<h3>DataGrid AllowSorting Example</h3>
<p>Select whether to allow sorting in the DataGrid control.<br />
<asp:CheckBox id="AllowSortingCheckBox"
Text="Allow sorting"
AutoPostBack="True"
Checked="True"
OnCheckedChanged="Check_Change"
runat="server"/></p>
<hr />
<b>Product List</b>
<asp:DataGrid id="ItemsGrid"
BorderColor="black"
BorderWidth="1"
CellPadding="3"
OnSortCommand="Sort_Grid"
UseAccessibleHeader="true"
AutoGenerateColumns="False"
AllowSorting="True"
runat="server">
<HeaderStyle BackColor="#00aaaa" />
<Columns>
<asp:BoundColumn DataField="IntegerValue"
SortExpression="IntegerValue"
HeaderText="Item"/>
<asp:BoundColumn DataField="StringValue"
SortExpression="StringValue"
HeaderText="Description"/>
<asp:BoundColumn DataField="CurrencyValue"
HeaderText="Price"
SortExpression="CurrencyValue"
DataFormatString="{0:c}">
<ItemStyle HorizontalAlign="Right">
</ItemStyle>
</asp:BoundColumn>
</Columns>
</asp:DataGrid>
</div>
</form>
</body>
</html>
Poznámky
Pokud je řazení povolené, LinkButton ovládací prvky se vykreslují v oddílu záhlaví každého sloupce, ve kterém SortExpression je vlastnost nastavená. Tyto LinkButton ovládací prvky umožňují seřadit DataGrid ovládací prvek podle vybraného sloupce. Jedinou výjimkou je použití TemplateColumn typu sloupce se HeaderTemplate sadou vlastností . V takovém případě musíte zadat Button ovládací prvek ve HeaderTemplate sloupci .
Událost SortCommand je vyvolána při kliknutí na LinkButton jeden z ovládacích prvků. Zadání kódu pro obslužnou rutinu události je na vás. Typickou logikou obslužné rutiny je seřazení seznamu a následné opětovné vazby dat k ovládacímu prvku DataGrid .