A common scenario is to apply default filter for the grid when the page in which the control resides is loaded in the browser. This can be achieved quite easily using the FilterExpression attribute of the grid (more about the filter expression you can learn from this topic) and the CurrentFilterFunction/CurrentFilterValue for the corresponding grid column. The actions for modifying these properties can take place inside the NeedDataSource handler inside !Page.IsPostBack conditional block.
The forthcoming code sample demonstrates this technique:
| ASPX/ASCX |
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<rad:RadGrid id="RadGrid1" runat="server" AllowFilteringByColumn="true" Width="500px" AllowPaging="true"
PageSize="15">
<PagerStyle Mode="NumericPages" />
<MasterTableView AutoGenerateColumns="false" AllowPaging="true" PageSize="15">
<Columns>
<rad:GridBoundColumn UniqueName="ContactName" HeaderText="Contact name" DataField="ContactName" AllowFiltering="false" />
<rad:GridBoundColumn UniqueName="City" HeaderText="City" DataField="City" />
<rad:GridBoundColumn UniqueName="PostalCode" HeaderText="Postal code" DataField="PostalCode" />
<rad:GridBoundColumn UniqueName="Country" HeaderText="Country" DataField="Country" />
</Columns>
</MasterTableView>
</rad:RadGrid> |
| VB.NET |
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Private Sub RadGrid1_NeedDataSource(ByVal source As System.Object, ByVal e As Telerik.WebControls.GridNeedDataSourceEventArgs) Handles RadGrid1.NeedDataSource
Dim MyOleDbConnection As New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0; Data Source=" + Server.MapPath
("~/Grid/Data/Access/Nwind.mdb"))
Dim MyOleDbDataAdapter As New OleDbDataAdapter
MyOleDbDataAdapter.SelectCommand = New OleDbCommand("SELECT ContactName, Country, City, PostalCode FROM Customers",
MyOleDbConnection)
Dim myDataTable As New DataTable
MyOleDbConnection.Open()
Try
MyOleDbDataAdapter.Fill(myDataTable)
Finally
MyOleDbConnection.Close()
End Try
RadGrid1.DataSource = myDataTable.DefaultView
If (Not Page.IsPostBack) Then
RadGrid1.MasterTableView.FilterExpression = "([Country] LIKE '%Germany%') "
Dim column As GridColumn = RadGrid1.MasterTableView.GetColumnSafe("Country")
column.CurrentFilterFunction = GridKnownFunction.Contains
column.CurrentFilterValue = "Germany"
End If
End Sub |
| 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 ContactName, Country, City, PostalCode FROM Customers",
MyOleDbConnection);
DataTable myDataTable = new DataTable();
MyOleDbConnection.Open();
try
{
MyOleDbDataAdapter.Fill(myDataTable);
}
finally
{
MyOleDbConnection.Close();
}
RadGrid1.DataSource = myDataTable.DefaultView;
if (!Page.IsPostBack)
{
RadGrid1.MasterTableView.FilterExpression = "([Country] LIKE \'%Germany%\') ";
GridColumn column = RadGrid1.MasterTableView.GetColumnSafe("Country");
column.CurrentFilterFunction = GridKnownFunction.Contains;
column.CurrentFilterValue = "Germany";
}
} |
In case you use data source control (part of ASP.NET 2.0), you do not need to subscribe to the NeedDataSource event of the grid but to the PreRender event of the control to perform the initial filtering:
| VB.NET |
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Protected Sub RadGrid1_PreRender(ByVal sender As Object, ByVal e As System.EventArgs) Handles RadGrid1.PreRender
If (Not Page.IsPostBack) Then
RadGrid1.MasterTableView.FilterExpression = "([Country] LIKE '%Germany%') "
Dim column As GridColumn = RadGrid1.MasterTableView.GetColumnSafe("Country")
column.CurrentFilterFunction = GridKnownFunction.Contains
column.CurrentFilterValue = "Germany"
RadGrid1.MasterTableView.Rebind()
End If
End Sub |
| C# |
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protected void RadGrid1_PreRender(object sender, System.EventArgs e)
{
if (!Page.IsPostBack)
{
RadGrid1.MasterTableView.FilterExpression = "([Country] LIKE \'%Germany%\') ";
GridColumn column = RadGrid1.MasterTableView.GetColumnSafe("Country");
column.CurrentFilterFunction = GridKnownFunction.Contains;
column.CurrentFilterValue = "Germany";
RadGrid1.MasterTableView.Rebind();
}
} |
Finally, when you have GridCheckBoxColumn the syntax for the FilterExpression is slightly different, for example:
| VB.NET |
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Protected Sub RadGrid1_PreRender(ByVal sender As Object, ByVal e As System.EventArgs) Handles RadGrid1.PreRender
If (Not Page.IsPostBack) Then
RadGrid1.MasterTableView.FilterExpression = "([chkBoxColumnDataField] = True) "
Dim column As GridColumn = RadGrid1.MasterTableView.GetColumnSafe("MyCheckBoxColumnUniqueName")
column.CurrentFilterFunction = GridKnownFunction.EqualTo
column.CurrentFilterValue = "True"
RadGrid1.MasterTableView.Rebind()
End If
End Sub |
| C# |
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protected void RadGrid1_PreRender(object sender, System.EventArgs e)
{
if (!Page.IsPostBack)
{
RadGrid1.MasterTableView.FilterExpression = "([chkBoxColumnDataField] = True) ";
GridColumn column = RadGrid1.MasterTableView.GetColumnSafe("MyCheckBoxColumnUniqueName");
column.CurrentFilterFunction = GridKnownFunction.EqualTo;
column.CurrentFilterValue = "True";
RadGrid1.MasterTableView.Rebind();
}
}. |