| Author: Ramya 02 Sep 2008 | Member Level: Gold | Rating: Points: -20 |
Binding columns dynamically in DataGrid
In this Article, you learn how to bind data in Bound column and Template column dynamically.
Binding columns dynamically in DataGrid
DataGrid one of the web server control, which displays data in tabular and read only format by default. Also capable of displaying editable controls automatically, during run time. Additionally it supports paging. Control must bind to a data source via its DataSource. By default DataGrid Control generates bound column for each field in the data source. When web page runs your code must call the control’s DataBind method to load the grid with data. In order to control the content and layout of the columns precisely, developer can define the following type of columns
BoundColumn.
Display textual fields. It renders as plain text but converts to a TextBox when the Datagrid is placed into Edit mode.
HyperLinkColumn
Display text data. Which also represents a Web address (URL). The URL may or may not be the same as the display text; both can be set independently. It renders as an <a href=...> tag.
ButtonColumn
Allowing user interaction with the grid on a row basis. It can be rendered as either a hyperlinked LinkButton (<a href=...>), or a Pushbutton (<input type="button">). A PostBack is triggered when the button is clicked, and the ItemCommand event is fired on the Datagrid.
EditCommandColumn
This is similar to ButtonColumn, but it automatically creates buttons for editing the Datagrid, and for canceling or submitting the changes made. Fires the ItemCommand event, plus the specific event for the button clicked, EditCommand, CancelCommand, or UpdateCommand.
TemplateColumn
Full control over what controls are displayed to the user, divided into different templates, such as ItemTemplate and EditItemTemplate. Any ASP.NET or HTML control or set of controls can be placed inside those templates.
In this Article, you learn how to bind data in Bound column and Template column dynamically. Here I am using Icollection interface to hold my data.
Private Function CreateDataSource() As ICollection
Dim dtExample As DataTable
Dim drExample As DataRow
Dim intI As Integer
dtExample = New DataTable()
' First Coluumn
dtExample.Columns.Add(New DataColumn("IntegerValue", GetType(Integer)))
' Second Column
dtExample.Columns.Add(New DataColumn("StringValue", GetType(String)))
' Itrate, and create 6 rows
For intI = 0 To 5
drExample = dtExample.NewRow()
drExample(0) = intI
drExample(1) = "Row :" & intI.ToString()
dtExample.Rows.Add(drExample)
Next
' Add rows into Data view and return as Collection
Return New DataView(dtExample)
End Function
Boundcolumn
To visualize data grid, we need some container, hear I am using a Label control as container to hold my grid.
My aspx file contains
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML>
<HEAD>
<title>BindingData</title>
<meta name="GENERATOR" content="Microsoft Visual Studio.NET 7.0">
<meta name="CODE_LANGUAGE" content="Visual Basic 7.0">
<meta name="vs_defaultClientScript" content="JavaScript">
<meta name="vs_targetSchema" content="http://schemas.microsoft.com/intellisense/ie5">
</HEAD>
<body MS_POSITIONING="GridLayout">
<form id="Form1" method="post" runat="server">
<asp:label id="lblShowGrid" runat="server" />
</form>
</body>
</HTML>
And code behind file contains BoundColumn procedure
Private Sub BoundColumn()
Dim DataGrid1 As New DataGrid()
' Binding Data Source
DataGrid1.DataSource = CreateDataSource()
DataGrid1.AutoGenerateColumns = False
' First column
Dim bc1 As New BoundColumn()
bc1.DataField = "IntegerValue"
bc1.HeaderText = "Row ID"
DataGrid1.Columns.Add(bc1)
' Second column
Dim bc2 As New BoundColumn()
bc2.DataField = "StringValue"
bc2.HeaderText = "Row Value"
' Adding columns to grid
DataGrid1.Columns.Add(bc2)
' Adding Datagrid to Label Control
lblShowGrid.Controls.Add(DataGrid1)
' Binding
DataGrid1.DataBind()
End Sub
In your page load, just call Bound column procedure.
Templatecolumn
Using ITemplate interface you can bind Template column dynamically with the help of ITemplate interface and its method called “InstantiateIn”
First step declare Template Column in your code behind file.
Private TempCol As New TemplateColumn()
Now Create a New Template Class
Public Class MyTemp
Implements ITemplate
Dim TemplateType As ListItemType
Dim Field1 As String
Dim Field2 As String
Sub New(ByVal type As ListItemType, ByVal fld1 As String, ByVal fld2 As String)
TemplateType = type
Field1 = fld1
Field2 = fld2
End Sub
Sub InstantiateIn(ByVal Container As Control) Implements ITemplate.InstantiateIn
Dim lbl1 As Label = New Label()
Dim lbl2 As Label = New Label()
Dim lc1 As LiteralControl = New LiteralControl()
Dim lc2 As LiteralControl = New LiteralControl()
Select Case TemplateType
Case ListItemType.Header
lc1.ID = "lc1"
lc1.Text = Field1
Container.Controls.Add(lc1)
lc2.ID = "lc2"
lc2.Text = Field2
Container.Controls.Add(lc2)
Case ListItemType.Item
lbl1.ID = "lbl1"
AddHandler lbl1.DataBinding, AddressOf BindIntegerColumn
Container.Controls.Add(lbl1)
lbl2.ID = "lbl2"
AddHandler lbl2.DataBinding, AddressOf BindStringColumn
Container.Controls.Add(lbl2)
End Select
End Sub
Sub BindIntegerColumn(ByVal Sender As Object, ByVal e As EventArgs)
Dim lbl1 As Label = CType(Sender, Label)
Dim Container As DataGridItem = CType(lbl1.NamingContainer, DataGridItem)
lbl1.Text = DataBinder.Eval(Container.DataItem, Field1)
End Sub
Sub BindStringColumn(ByVal sender As Object, ByVal e As EventArgs)
Dim lbl2 As Label = CType(sender, Label)
Dim Container As DataGridItem = CType(lbl2.NamingContainer, DataGridItem)
lbl2.Text = DataBinder.Eval(Container.DataItem, Field2)
End Sub
Add the following method in your code behind and call this procedure in your page load.
Private Sub Template()
Dim DataGrid1 As New DataGrid()
DataGrid1.AutoGenerateColumns = False
Dim Field1 As String
Dim Field2 As String
Dim Header1 As String
Dim Header2 As String
Field1 = "IntegerValue"
Field2 = "StringValue"
Header1 = "Row ID"
Header2 = "Row Value"
' Header Template
TempCol.HeaderTemplate = New MyTemp(ListItemType.Header, Header1, Header2)
' Item Template
TempCol.ItemTemplate = New MyTemp(ListItemType.Item, Field1, Field2)
' Add Template into Grid
DataGrid1.Columns.Add(TempCol)
' Binding Data Source
DataGrid1.DataSource = CreateDataSource()
DataGrid1.DataBind()
' Bind Grid into Label
Me.lblShowGrid.Controls.Add(DataGrid1)
End Sub
My Page Load look like
Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
'Put user code to initialize the page here
BoundColumn()
Template()
End Sub
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