There are numerous situations in which you may need to get reference to controls in grid row/edit form and modify their state depending on the option the user chooses for another control in the same row/edit form. Basically, you can reference the grid item which wraps the controls (either data item or edit form item), then locate the other control and modify its state as per your custom needs. In some cases (when there are additional containers in the rows), you may need to find the container first and then propagate the same steps (depicted above).
The upcoming code sample represents how to alter the color for the City column on checkbox state change and how to load different set of items for combo in par with the user selection in another combo. Please note that the items refresh action is not included:
| ASPX/ASCX |
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<rad:radgrid id="RadGrid1" runat="server" Width="400px" EnableAJAXLoadingTemplate="false" EnableAJAX="true">
<MasterTableView AutoGenerateColumns="false">
<Columns>
<rad:GridTemplateColumn UniqueName="TemplateColumn" HeaderText="Check/UnCheck">
<ItemTemplate>
<asp:Panel ID="Panel1" Runat="server">
<asp:CheckBox ID="CheckBox1" Runat="server" AutoPostBack="true" OnCheckedChanged="CheckedChanged" />
</asp:Panel>
</ItemTemplate>
</rad:GridTemplateColumn>
<rad:GridDropDownColumn UniqueName="ddlContactName" ListTextField="ContactName" ListValueField="CustomerID"
ListDataMember="Customers" DataField="CustomerID" HeaderText="Contact name" />
<rad:GridBoundColumn UniqueName="City" DataField="City" HeaderText="City" />
<rad:GridDropDownColumn UniqueName="ddlContactTitle" ListTextField="ContactTitle" ListValueField="CustomerID"
ListDataMember="Customers" DataField="CustomerID" HeaderText="Contact title" />
<rad:GridEditCommandColumn UniqueName="EditCommandColumn" />
</Columns>
</MasterTableView>
</rad:radgrid> |
| C# |
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private void RadGrid1_NeedDataSource(object source, Telerik.WebControls.GridNeedDataSourceEventArgs e)
{
OleDbConnection MyOleDbConnection = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0; Data Source=" + Server.MapPath
("~/Grid/Data/Access/Nwind.mdb"));
OleDbDataAdapter MyOleDbDataAdapter = new OleDbDataAdapter();
MyOleDbDataAdapter.SelectCommand = new OleDbCommand("SELECT TOP 5 CustomerID, ContactName, ContactTitle, City FROM Customers",
MyOleDbConnection);
DataTable myDataTable = new DataTable();
MyOleDbConnection.Open();
try
{
MyOleDbDataAdapter.Fill(myDataTable);
}
finally
{
MyOleDbConnection.Close();
}
RadGrid1.DataSource = myDataTable.DefaultView;
}
private void RadGrid1_ItemCreated(object sender, Telerik.WebControls.GridItemEventArgs e)
{
if (e.Item is GridEditableItem && e.Item.IsInEditMode)
{
//the dropdown list will be the first control in the Controls collection of the corresponding cell
DropDownList list = (e.Item as GridEditableItem)["ddlContactName"].Controls[0] as DropDownList;
//attach SelectedIndexChanged event for the drodown control
list.AutoPostBack = true;
list.SelectedIndexChanged += new System.EventHandler(this.list_SelectedIndexChanged);
}
}
private void list_SelectedIndexChanged(object sender, System.EventArgs e)
{
//first reference the edited grid item through the NamingContainer attribute
GridEditableItem editedItem = (sender as DropDownList).NamingContainer as GridEditableItem;
//the dropdown list will be the first control in the Controls collection of the corresponding cell
//for custom edit forms (WebUserControl/FormTemplate) you can find the column editor with the FindControl(controlId) method
DropDownList ddList = editedItem["ddlContactTitle"].Controls[0] as DropDownList;
// change the data source for ContactTitle with custom code here
DataTable table = DataSourceHelperCS.GetDataTable("SELECT CustomerID, ContactTitle FROM Customers WHERE ContactName = '" + (editedItem
["ddlContactName"].Controls[0] as DropDownList).SelectedItem.Text + "'");
ddList.DataSource = table;
ddList.DataBind();
RadGrid1.Controls.Add(new LiteralControl("<b>the available options for Contact Title has been changed</b>"));
}
protected void CheckedChanged(object sender, System.EventArgs e)
{
CheckBox chkBox = (sender as CheckBox);
//find the City field in the row and change its color
//first reference the panel which wraps the checkbox control through the Parent property
Panel myPanel = chkBox.Parent as Panel;
//then fetch the grid data item through the NamingContainer attribute of the container control (panel in this case)
GridDataItem dataItem = myPanel.NamingContainer as GridDataItem;
//finally modify the color for the City field according to the checkbox status
if(chkBox.Checked)
{
dataItem["City"].Style["color"] = "red";
}
else
{
dataItem["City"].Style["color"] = "black";
}
} |
| VB.NET |
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Private Sub RadGrid1_NeedDataSource(ByVal source As Object, ByVal e As Telerik.WebControls.GridNeedDataSourceEventArgs) Handles RadGrid1.NeedDataSource
Dim MyOleDbConnection As OleDbConnection = New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0; Data Source=" + Server.MapPath
("~/Grid/Data/Access/Nwind.mdb"))
Dim MyOleDbDataAdapter As OleDbDataAdapter = New OleDbDataAdapter
MyOleDbDataAdapter.SelectCommand = New OleDbCommand("SELECT TOP 5 CustomerID, ContactName, ContactTitle, City FROM Customers",
MyOleDbConnection)
Dim myDataTable As DataTable = New DataTable
MyOleDbConnection.Open
Try
MyOleDbDataAdapter.Fill(myDataTable)
Finally
MyOleDbConnection.Close
End Try
RadGrid1.DataSource = myDataTable.DefaultView
End Sub
Private Sub RadGrid1_ItemCreated(ByVal sender As Object, ByVal e As Telerik.WebControls.GridItemEventArgs) Handles RadGrid1.ItemCreated
If (TypeOf e.Item is GridEditableItem AndAlso e.Item.IsInEditMode) Then
Dim list As DropDownList = CType(CType(e.Item,GridEditableItem)("ddlContactName").Controls(0),DropDownList)
list.AutoPostBack = true
AddHandler list.SelectedIndexChanged, AddressOf Me.list_SelectedIndexChanged
End If
End Sub
Private Sub list_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs)
Dim editedItem As GridEditableItem = CType(CType(sender,DropDownList).NamingContainer,GridEditableItem)
Dim ddList As DropDownList = CType(editedItem("ddlContactTitle").Controls(0),DropDownList)
Dim table as DataTable = DataSourceHelperCS.GetDataTable("SELECT CustomerID, ContactTitle FROM Customers WHERE ContactName = '" &
(editedItem["ddlContactName"].Controls[0] as DropDownList).SelectedItem.Text + "'")
ddList.DataSource = table
ddList.DataBind()
RadGrid1.Controls.Add(New LiteralControl("<b>the available options for Contact Title has been changed</b>"))
End Sub
Protected Sub CheckedChanged(ByVal sender As Object, ByVal e As System.EventArgs)
Dim chkBox As CheckBox = CType(sender,CheckBox)
Dim myPanel As Panel = CType(chkBox.Parent,Panel)
Dim dataItem As GridDataItem = CType(myPanel.NamingContainer,GridDataItem)
If chkBox.Checked Then
dataItem("City").Style("color") = "red"
Else
dataItem("City").Style("color") = "black"
End If
End Sub |