How to reuse grid template columns

[Michel]

I have a number of grids that partly share the same structure. For example, many grids have 'Id', 'Description', 'DisplayOrder', 'LastUpdateDate' and 'LastUpdateUserId' columns that are identical. The GridTemplateColumn for these common columns are all set declaratively the same in the different grids.

I would like to know what is the best approach in reusing some code.

For example, I considered creating a web user control for each column, but this did not work (as it seems that the telerik:GridTemplateColumn tag was not recognized in the ascx file and also that the control in the columns section has to be a 'Telerik.Web.UI.GridColumn').

Thanks.

[Nikolay Rusev]

Hello Michel,

There are few examples that utilize GridTemplateColumn for reusing the code. You should be able to do the same with the one that you are using. Please check the links for reference:
http://www.telerik.com/help/aspnet-ajax/grdimplementingfilteringfortemplatecolumns.html
http://demos.telerik.com/aspnet-ajax/grid/examples/programming/filteringtemplatecolumns/defaultcs.aspx

Best wishes,
Nikolay
the Telerik team

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[Michel]

Thanks for the tip Nikolay.

Using web custom controls will probably do the trick.

It took a while to get it to work properly and I had to research defining template programmatically, but everything now seems ok. Let me share my code for others that would like to do the same.

I used to have this.

<telerik:RadGrid
    ID="SeasonCategoriesGrid"
    runat="server"
    (...)>
    <MasterTableView
        (...)>
        <Columns>
            <telerik:GridTemplateColumn
                DataField="Description"
                FilterControlWidth="115px"
                HeaderStyle-Width="160px"
                HeaderText="<%$ Resources:Global, Description%>"
                SortExpression="Description">
                <ItemTemplate>
                    <%# Eval("Description") %>
                </ItemTemplate>
                <EditItemTemplate>
                    <wcc:TextInput
                        ID="DescriptionInput"
                        runat="server"
                        IsRequired="true"
                        MaxLength="25"
                        Text='<%# Bind("Description") %>' />
                </EditItemTemplate>
            </telerik:GridTemplateColumn>

            (...)

        </Columns>
    </MasterTableView>
</telerik:RadGrid>

And I now have this.

<telerik:RadGrid
    ID="SeasonCategoriesGrid"
    runat="server"
    (...)>
    <MasterTableView
        (...)>
        <Columns>
            <wcc:DescriptionGridTemplateColumn />

            (...)

        </Columns>
    </MasterTableView>
</telerik:RadGrid>

 

Namespace MyWebCustomControls

    Public Class DescriptionGridTemplateColumn
        Inherits Telerik.Web.UI.GridTemplateColumn

        Public Sub New()
            Me.ItemTemplate = New DescriptionItemTemplate()
            Me.EditItemTemplate = New DescriptionEditItemTemplate()

            Me.DataField = "Description"
            Me.FilterControlWidth = New Unit(115, UnitType.Pixel)
            Me.HeaderStyle.Width = New Unit(160, UnitType.Pixel)
            Me.HeaderText = Resources.Global.Description
            Me.SortExpression = "Description"
        End Sub

        Private Class DescriptionItemTemplate
            Implements IBindableTemplate

            Private _description As WebControls.Literal

            Public Sub InstantiateIn(ByVal container As Control) Implements IBindableTemplate.InstantiateIn
                _description = New WebControls.Literal()
                AddHandler _description.DataBinding, AddressOf Me.Description_Databinding
                container.Controls.Add(_description)
            End Sub

            Public Sub Description_Databinding(ByVal sender As Object, ByVal e As EventArgs)
                Dim dataItem As Telerik.Web.UI.GridDataItem = DirectCast(CType(sender, Control).NamingContainer, Telerik.Web.UI.GridDataItem)
                CType(sender, WebControls.Literal).Text = CStr(DataBinder.Eval(dataItem.DataItem, "Description"))
            End Sub

            ' It seems that in order to perform deletes, the ItemTemplane needs to
            ' not only implement ITemplate, but also IBindable Template.
            ' Therefore the ExtractValues method needs to be implemented, but I don't beleive
            ' that the returned data is really used for anything.
            Public Function ExtractValues(ByVal container As System.Web.UI.Control) As System.Collections.Specialized.IOrderedDictionary Implements IBindableTemplate.ExtractValues
                Return New Collections.Specialized.OrderedDictionary()
            End Function

        End Class

        Private Class DescriptionEditItemTemplate
            Implements IBindableTemplate

            Private _descriptionInput As MyWebCustomControls.TextInput

            Public Sub InstantiateIn(ByVal container As Control) Implements IBindableTemplate.InstantiateIn
                _descriptionInput = New MyWebCustomControls.TextInput()
                _descriptionInput.ID = "DescriptionInput"
                _descriptionInput.IsRequired = "true"
                _descriptionInput.MaxLength = "25"
                AddHandler _descriptionInput.DataBinding, AddressOf Me.DescriptionInput_Databinding
                container.Controls.Add(_descriptionInput)
            End Sub

            Public Sub DescriptionInput_Databinding(ByVal sender As Object, ByVal e As EventArgs)
                Dim dataItem As Telerik.Web.UI.GridEditFormItem = DirectCast(CType(sender, Control).NamingContainer, Telerik.Web.UI.GridEditFormItem)
                CType(sender, MyWebCustomControls.TextInput).Text = TryCast(DataBinder.Eval(dataItem.DataItem, "Description"), String)
            End Sub

            Public Function ExtractValues(ByVal container As Control) As Collections.Specialized.IOrderedDictionary Implements IBindableTemplate.ExtractValues
                Dim returnDictionary As Collections.Specialized.OrderedDictionary = New Collections.Specialized.OrderedDictionary()
                returnDictionary.Add("Description", (DirectCast(((DirectCast(container, Telerik.Web.UI.GridEditFormItem)).FindControl("DescriptionInput")), MyWebCustomControls.TextInput)).Text)
                Return returnDictionary
            End Function

        End Class

    End Class

End Namespace

(Note that "wcc" refers to my custom controls in the MyWebCustomControls namespace.)

As you can see, instead of specifying the ItemTemplate, ItemEditTemplate and properties declaratively for my description GridTemplateColumn, this can now be replaced by a single line.

It does take a little work to set up the web customs classes for each of my columns, but given that these are repeated in a few grids, I have less lines of code. In addition I gain all the benefits of code reuse.