TemplateField Constructeur
Définition
Important
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Initialise une nouvelle instance de la classe TemplateField.
public:
TemplateField();
public TemplateField ();
Public Sub New ()
Exemples
L’exemple de code suivant montre comment utiliser le constructeur pour ajouter dynamiquement une TemplateField colonne de champ à un GridView contrôle.
<%@ Page language="C#" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
// Create a template class to represent a dynamic template column.
public class GridViewTemplate : ITemplate
{
private DataControlRowType templateType;
private string columnName;
public GridViewTemplate(DataControlRowType type, string colname)
{
templateType = type;
columnName = colname;
}
public void InstantiateIn(System.Web.UI.Control container)
{
// Create the content for the different row types.
switch(templateType)
{
case DataControlRowType.Header:
// Create the controls to put in the header
// section and set their properties.
Literal lc = new Literal();
lc.Text = "<b>" + columnName + "</b>";
// Add the controls to the Controls collection
// of the container.
container.Controls.Add(lc);
break;
case DataControlRowType.DataRow:
// Create the controls to put in a data row
// section and set their properties.
Label firstName = new Label();
Label lastName = new Label();
Literal spacer = new Literal();
spacer.Text = " ";
// To support data binding, register the event-handling methods
// to perform the data binding. Each control needs its own event
// handler.
firstName.DataBinding += new EventHandler(this.FirstName_DataBinding);
lastName.DataBinding += new EventHandler(this.LastName_DataBinding);
// Add the controls to the Controls collection
// of the container.
container.Controls.Add(firstName);
container.Controls.Add (spacer);
container.Controls.Add(lastName);
break;
// Insert cases to create the content for the other
// row types, if desired.
default:
// Insert code to handle unexpected values.
break;
}
}
private void FirstName_DataBinding(Object sender, EventArgs e)
{
// Get the Label control to bind the value. The Label control
// is contained in the object that raised the DataBinding
// event (the sender parameter).
Label l = (Label)sender;
// Get the GridViewRow object that contains the Label control.
GridViewRow row = (GridViewRow)l.NamingContainer;
// Get the field value from the GridViewRow object and
// assign it to the Text property of the Label control.
l.Text = DataBinder.Eval(row.DataItem, "au_fname").ToString();
}
private void LastName_DataBinding(Object sender, EventArgs e)
{
// Get the Label control to bind the value. The Label control
// is contained in the object that raised the DataBinding
// event (the sender parameter).
Label l = (Label)sender;
// Get the GridViewRow object that contains the Label control.
GridViewRow row = (GridViewRow)l.NamingContainer;
// Get the field value from the GridViewRow object and
// assign it to the Text property of the Label control.
l.Text = DataBinder.Eval(row.DataItem, "au_lname").ToString();
}
}
void Page_Load(Object sender, EventArgs e)
{
// The field columns need to be created only when the page is
// first loaded.
if (!IsPostBack)
{
// Dynamically create field columns to display the desired
// fields from the data source. Create a TemplateField object
// to display an author's first and last name.
TemplateField customField = new TemplateField();
// Create the dynamic templates and assign them to
// the appropriate template property.
customField.ItemTemplate = new GridViewTemplate(DataControlRowType.DataRow, "Author Name");
customField.HeaderTemplate = new GridViewTemplate(DataControlRowType.Header, "Author Name");
// Add the field column to the Columns collection of the
// GridView control.
AuthorsGridView.Columns.Add(customField);
}
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>TemplateField Constructor Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>TemplateField Constructor Example</h3>
<asp:gridview id="AuthorsGridView"
datasourceid="AuthorsSqlDataSource"
autogeneratecolumns="False"
runat="server">
</asp:gridview>
<!-- This example uses Microsoft SQL Server and connects -->
<!-- to the Pubs sample database. -->
<asp:sqldatasource id="AuthorsSqlDataSource"
selectcommand="SELECT [au_fname], [au_lname] FROM [authors]"
connectionstring="server=localhost;database=pubs;integrated security=SSPI"
runat="server">
</asp:sqldatasource>
</form>
</body>
</html>
<%@ Page language="VB" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
' Create a template class to represent a dynamic template column.
Public Class GridViewTemplate
Implements ITemplate
Private templateType As DataControlRowType
Private columnName As String
Sub New(ByVal type As DataControlRowType, ByVal colname As String)
templateType = type
columnName = colname
End Sub
Sub InstantiateIn(ByVal container As System.Web.UI.Control) _
Implements ITemplate.InstantiateIn
' Create the content for the different row types.
Select Case templateType
Case DataControlRowType.Header
' Create the controls to put in the header
' section and set their properties.
Dim lc As New Literal
lc.Text = "<b>" & columnName & "</b>"
' Add the controls to the Controls collection
' of the container.
container.Controls.Add(lc)
Case DataControlRowType.DataRow
' Create the controls to put in a data row
' section and set their properties.
Dim firstName As New Label
Dim lastName As New Label
Dim spacer = New Literal
spacer.Text = " "
' To support data binding, register the event-handling methods
' to perform the data binding. Each control needs its own event
' handler.
AddHandler firstName.DataBinding, AddressOf FirstName_DataBinding
AddHandler lastName.DataBinding, AddressOf LastName_DataBinding
' Add the controls to the Controls collection
' of the container.
container.Controls.Add(firstName)
container.Controls.Add(spacer)
container.Controls.Add(lastName)
' Insert cases to create the content for the other
' row types, if desired.
Case Else
' Insert code to handle unexpected values.
End Select
End Sub
Private Sub FirstName_DataBinding(ByVal sender As Object, ByVal e As EventArgs)
' Get the Label control to bind the value. The Label control
' is contained in the object that raised the DataBinding
' event (the sender parameter).
Dim l As Label = CType(sender, Label)
' Get the GridViewRow object that contains the Label control.
Dim row As GridViewRow = CType(l.NamingContainer, GridViewRow)
' Get the field value from the GridViewRow object and
' assign it to the Text property of the Label control.
l.Text = DataBinder.Eval(row.DataItem, "au_fname").ToString()
End Sub
Private Sub LastName_DataBinding(ByVal sender As Object, ByVal e As EventArgs)
' Get the Label control to bind the value. The Label control
' is contained in the object that raised the DataBinding
' event (the sender parameter).
Dim l As Label = CType(sender, Label)
' Get the GridViewRow object that contains the Label control.
Dim row As GridViewRow = CType(l.NamingContainer, GridViewRow)
' Get the field value from the GridViewRow object and
' assign it to the Text property of the Label control.
l.Text = DataBinder.Eval(row.DataItem, "au_lname").ToString()
End Sub
End Class
Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)
' The field columns need to be created only when the page is
' first loaded.
If Not IsPostBack Then
' Dynamically create field columns to display the desired
' fields from the data source. Create a TemplateField object
' to display an author's first and last name.
Dim customField As New TemplateField
' Create the dynamic templates and assign them to
' the appropriate template property.
customField.ItemTemplate = New GridViewTemplate(DataControlRowType.DataRow, "Author Name")
customField.HeaderTemplate = New GridViewTemplate(DataControlRowType.Header, "Author Name")
' Add the field column to the Columns collection of the
' GridView control.
AuthorsGridView.Columns.Add(customField)
End If
End Sub
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>TemplateField Constructor Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>TemplateField Constructor Example</h3>
<asp:gridview id="AuthorsGridView"
datasourceid="AuthorsSqlDataSource"
autogeneratecolumns="False"
runat="server">
</asp:gridview>
<!-- This example uses Microsoft SQL Server and connects -->
<!-- to the Pubs sample database. -->
<asp:sqldatasource id="AuthorsSqlDataSource"
selectcommand="SELECT [au_fname], [au_lname] FROM [authors]"
connectionstring="server=localhost;database=pubs;integrated security=SSPI"
runat="server">
</asp:sqldatasource>
</form>
</body>
</html>
Remarques
Utilisez ce constructeur pour initialiser une nouvelle instance de la TemplateField classe . Ce constructeur est couramment utilisé lors de l’ajout de champs à un contrôle lié aux données créé dynamiquement.
Pour ajouter dynamiquement un TemplateField objet à un contrôle lié aux données, créez un TemplateField objet, définissez les modèles appropriés, puis ajoutez-le à la collection de champs du contrôle lié aux données. Par exemple, si vous utilisez le GridView contrôle, ajoutez l’objet TemplateField à la Columns collection.
Notes
Bien que vous puissiez ajouter dynamiquement des champs à un contrôle lié aux données, il est vivement recommandé de déclarer statiquement les champs, puis de les afficher ou de les masquer, le cas échéant. La déclaration statique de tous vos champs réduit la taille de l’état d’affichage pour le contrôle lié aux données parent.