Replacing FilterTemplate On AutoGenerated Column

[Ben]

I have a RADGrid that generates columns automatically by assigning the DataSource to a LIST (OF <Object>) array. (I generate the grid entirely through server-side code). My client now wants to be able to filter off any column. There are some columns that have very specific data, and I would like to show then a "DropDownList" as opposed to a textbox. I created an ITemplate object, and within the "InstantiateIn()" method I created my RADCombobox (I also tried using a regular ASP DropdownList). I also implemented code in Delegate Methods to handle both the DataBind() and the SelectedIndexChanged() events for the control.

I then added code to the Grid's "ColumnCreated()" method that replaced the FilterTemplate with my custom ITemplate if the column name matched the one that I want to replace. So far, everthing worked perfectly...my control appeared in place of the usual filter control, and it was populated with the correct data.

I had an extremely irritating problem with an out-of-sync ViewState error whenever any control on the same page tried to perform a
PostBack...after hours of searching, I ended up turning "EnableViewState" off on the DropDownList control.

Now, when I select an item in my DropDownList filter control, I see the AjaxPanel's rotating circle skin appear as usual, however the control's "SelectedIndexChanged()" event never fires. Any thoughts?

[Princy]

Hi Ben,

Here is a sample code snippet that shows creating a FilterTemplate for a column. Please try it, if this doesn't help, provide your full code snippet.

C#:

RadGrid RadGrid1;
private void Page_Init(object sender, System.EventArgs e)
 {
    RadGrid1 = new RadGrid();
    RadGrid1.ID = "RadGrid1";
    RadGrid1.NeedDataSource += new GridNeedDataSourceEventHandler(RadGrid1_NeedDataSource);

    string ColumnName = "Country";
    GridBoundColumn boundColumn;
   boundColumn = new GridBoundColumn();
   boundColumn.FilterTemplate = new MyTemplate(ColumnName, RadGrid1);
    RadGrid1.MasterTableView.Columns.Add(boundColumn);
   boundColumn.DataField = ColumnName;
   boundColumn.HeaderText = ColumnName;
   boundColumn.UniqueName = ColumnName;

    PlaceHolder1.Controls.Add(RadGrid1);
 }

private class MyTemplate : ITemplate
 {
    protected RadComboBox combo;
    private string colname;
    RadGrid radgrid;
    public MyTemplate(string cName,RadGrid grid)
    {
        colname = cName;
        radgrid = grid;
    }
    public void InstantiateIn(System.Web.UI.Control container)
    {
        combo = new RadComboBox();
        combo.ID = "RadComboBoxControl";
        combo.DataBinding += new EventHandler(RadComboBoxControl_DataBinding);
        container.Controls.Add(combo);
        combo.AutoPostBack = true;
        combo.SelectedIndexChanged += new RadComboBoxSelectedIndexChangedEventHandler(RadComboBoxControl_SelectedIndexChanged);
    }

    public void RadComboBoxControl_DataBinding(object sender, EventArgs e)
    {
        RadComboBox combo = (RadComboBox)sender;
        GridFilteringItem container = (GridFilteringItem)combo.NamingContainer;
        combo.DataTextField = colname;
        combo.DataValueField = colname;
        combo.DefaultItem.Text = "All";
        combo.DataSource = dt;
    }

    void RadComboBoxControl_SelectedIndexChanged(object sender, RadComboBoxSelectedIndexChangedEventArgs e)
    {
        RadComboBox combo = sender as RadComboBox;
        string filterExpression;
        filterExpression = "([Country] LIKE '" + e.Value + "')";
        radgrid.MasterTableView.FilterExpression = filterExpression;
        radgrid.MasterTableView.Rebind();
    }
 }

Thanks,
Princy

[RB]

What is dt in the current line: 

  combo.DataSource = dt;

[Princy]

Hi,

I'm setting the DataSource of the RadComboBox using a DataTable.

C#:

dt = GetDataTable("SELECT distinct Country FROM Customers");
combo.DataSource = dt;
. . . .
public static DataTable GetDataTable(string query)
{
    string ConnString = ConfigurationManager.ConnectionStrings["Northwind_newConnectionString3"].ConnectionString;
    SqlConnection conn = new SqlConnection(ConnString);
    SqlDataAdapter adapter = new SqlDataAdapter();
    adapter.SelectCommand = new SqlCommand(query, conn);

    DataTable myDataTable = new DataTable();

    conn.Open();
    try
    {
        adapter.Fill(myDataTable);
    }
    finally
    {
        conn.Close();
    }
    return myDataTable;
}

Thanks,
Princy

[RB]

I implemented your example. How can I make the dropdown display only unique values.Also the filtering fails. Whenever an item is selected, is there a method which should be implemented to handle it?

 <span style="color:blue;">void</span> RadComboBoxControl_SelectedIndexChanged(<span style="color:blue;">object</span> sender, <span style="color:#2b91af;">RadComboBoxSelectedIndexChangedEventArgs</span> e)
    {
        <span style="color:#2b91af;">RadComboBox</span> combo = sender <span style="color:blue;">as</span> <span style="color:#2b91af;">RadComboBox</span>;
        <span style="color:blue;">string</span> filterExpression;
        filterExpression = <span style="color:#a31515;">"([Reason] LIKE '"</span> + e.Value + <span style="color:#a31515;">"')"</span>;
        radgrid.MasterTableView.FilterExpression = filterExpression;
        radgrid.MasterTableView.Rebind();
    }

[Princy]

Hi,

Its hard to identify the issue with so little information. The code works fine at my end, can you please provide your full code snippet.
You can have distinct values in the RadComboBox by querying it to contain values that you need. Like in my sample code, I have used a DataTable, in that I'm adding distinct country names, which is set as the DataSource to the RadComboBox. Make sure you have set RadcomboBox  AutoPostBack property to true so as the SelectedIndexChanged and filter the values accordingly. Can you use breakpoints and find out if its taking the FilterExpression correct.

Thanks,
Princy

[RB]

I tried your example above. But the default value "All" is not being displayed!
combo.DefaultItem.Text = "All";

I also tried this after DataBind()
 combo.Items.Insert(0, new Telerik.Web.UI.RadComboBoxItem { Text = "All", Value = "-1" });
        combo.SelectedIndex = 0;
But even this doesnt display "All" on the top of the dropdown.

My DataBinding code is as follows:
 public void RadComboBoxControl_DataBinding(object sender, EventArgs e)
    {
        RadComboBox combo = (RadComboBox)sender;
        GridFilteringItem container = (GridFilteringItem)combo.NamingContainer;

        combo.DataTextField = colname;
        combo.DataValueField = colname;
        combo.EnableAutomaticLoadOnDemand = true;
        combo.AllowCustomText = true;
        try
        {
            if (this.popId > 0)
                combo.DataSource = new PopCapabilityRule_ListByPopId().ExecuteTypedDataTable(popId).SelectDistinct(colname);
            else
                combo.DataSource = new PopCapabilityRule_List().ExecuteTypedDataTable().SelectDistinct(colname);
        }
        catch (Exception exception)
        {
            GlobalCrossing.Ucommand.Library.ErrorManager.LogCriticalError(this.GetType().Name, System.Environment.MachineName, SessionMatrix.Current.IFOPrincipal.UserId, "", "80", exception.Message, "-3836364", exception);
        }
       
        combo.DataBind();
        combo.Items.Insert(0, new Telerik.Web.UI.RadComboBoxItem { Text = "All", Value = "-1" });
        combo.SelectedIndex = 0;
    }

[RB]

public void RadComboBoxControl_DataBinding(object sender, EventArgs e)
   {
       RadComboBox combo = (RadComboBox)sender;
       GridFilteringItem container = (GridFilteringItem)combo.NamingContainer;


       combo.DataTextField = colname;
       combo.DataValueField = colname;
       combo.EnableAutomaticLoadOnDemand = true;
       combo.AllowCustomText = true;
       try
       {
           if (this.popId > 0)
               combo.DataSource = new PopCapabilityRule_ListByPopId().ExecuteTypedDataTable(popId).SelectDistinct(colname);
           else
               combo.DataSource = new PopCapabilityRule_List().ExecuteTypedDataTable().SelectDistinct(colname);
       }
       catch (Exception exception)
       {
           GlobalCrossing.Ucommand.Library.ErrorManager.LogCriticalError(this.GetType().Name, System.Environment.MachineName, SessionMatrix.Current.IFOPrincipal.UserId, "", "80", exception.Message, "-3836364", exception);
       }

       combo.DataBind();
       combo.Items.Insert(0, new Telerik.Web.UI.RadComboBoxItem { Text = "All", Value = "-1" });
       combo.SelectedIndex = 0;
   }

[Princy]

Hi,

Please try setting the AppendDataBoundItems property to true for the RadComboBox.

C#:

RadComboBox combo = (RadComboBox)sender;
. . .
combo.AllowCustomText = true;
combo.AppendDataBoundItems = true;
. . .

Thanks,
Princy

[RB]

Thanks. It worked. I am trying to implement "All" option. On click of "All" the event RadComboBoxControl_SelectedIndexChanged is not triggered. Which event will handle this?

[Princy]

Hi,

Please try the below sample code snippet, I have modified the code and "All" option works fine now.

ASPX:

<asp:Panel ID="Panel1" runat="server"></asp:Panel>

C#:

{
  protected void Page_Init(object sender, EventArgs e)
   {
     RadGrid grid = new RadGrid();
     grid.ID = "RadGrid1";
     grid.AllowFilteringByColumn = true;
     grid.AutoGenerateColumns = false;
     grid.NeedDataSource += new GridNeedDataSourceEventHandler(grid_NeedDataSource);

     GridBoundColumn boundColumn = new GridBoundColumn();
     boundColumn.DataField = "CustomerID";
     boundColumn.HeaderText = "CustomerID";
     boundColumn.UniqueName = "CustomerID";
     boundColumn.AllowFiltering = false;
     grid.MasterTableView.Columns.Add(boundColumn);

     boundColumn = new GridBoundColumn();
     boundColumn.DataField = "Country";
     boundColumn.HeaderText = "Country";
     boundColumn.UniqueName = "Country";
     boundColumn.FilterTemplate = new ComboFilterTemplate(Page, "Country", "Country");
     grid.MasterTableView.Columns.Add(boundColumn);

     Panel1.Controls.Add(grid);
   }
   void grid_NeedDataSource(object source, GridNeedDataSourceEventArgs e)
   {
      DataTable dt = GetDataTable("SELECT CustomerID, Country FROM Customers");
     (source as RadGrid).DataSource = dt;
   }
}
public class ComboFilterTemplate : ITemplate
{
 private RadComboBox combo;
 private string columnName;
 protected string field;
 protected String connectionString;
 protected Page page;

 public ComboFilterTemplate(Page Page, string ColumnName, string Field)
 {
     field = Field;
     columnName = ColumnName;
     page = Page;
 }
 public void InstantiateIn(Control container)
 {
     combo = new RadComboBox();
     combo.ID = String.Format("RadComboBox{0}", columnName);
     combo.AppendDataBoundItems = true;
     if (field.Length > 0)
         combo.DataTextField = field;
     combo.DataValueField = field;
     combo.EmptyMessage = "Select";
     combo.Items.Insert(0, new RadComboBoxItem("All"));
     combo.DataBound += combo_DataBound;
     combo.DataBinding += new EventHandler(combo_DataBinding);
     combo.OnClientSelectedIndexChanged = String.Format("ClientComboFilterSelected_{0}", columnName);
     container.Controls.Add(combo);
 }

 void combo_DataBinding(object sender, EventArgs e)
 {
     DataTable dt = GetDataTable("SELECT distinct Country FROM Customers");
     combo.DataSource = dt;
     combo.DataTextField = columnName;
     combo.DataValueField = columnName;
 }

 void combo_DataBound(object sender, EventArgs e)
 {
     RadComboBox combo = (RadComboBox)sender;
     GridItem container = (GridItem)combo.NamingContainer;
     string script = "function ClientComboFilterSelected_" + columnName + "(sender,args){var tableView=$find(\""
         + ((GridItem)container).OwnerTableView.ClientID + "\");tableView.filter(\""
         + field + "\",args.get_item().get_value(),\"EqualTo\");}";
     ScriptManager.RegisterStartupScript(page, page.GetType(), String.Format("ClientComboFilterSelected_{0}", field), script, true);
     combo.SelectedValue = container.OwnerTableView.GetColumn(columnName).CurrentFilterValue;
   }
}

Thanks,
Princy