Binding Grid to Business Object with dynamic/undeclared properties

[Avidan]

I am looking for a solution for the following requirements/sceario.

I have factory object (like User Factory) which generate a binding list of business objects (like User). Each business object can store dynamic list of its attributes (in one case it might contains only 3 attributes and in another case it might contains 10 attributes. The attributes and their values are stored in Dictionary(of String, Object) and are exposed via single property called Field(columnname), where columnname is the dictionary key to access its value. The business object implements ICustomTypedProperty interface

I wish to bind the list of objects to a RadGrid, I know that binding is impossible since I cannot bind GridColumn to the Field property with a parameter. I believe that the right solution is to inherit the RadGrid control and the GridBoundColumn control, but I don't know how and when (which event to use) to bind cell value using the GetValue/SetValue methods (of the ICustomTypedProperty interface)

I will appreciate if you can provide me with an example (in VB) that works.

Avidan

[Daniel]

Hello Avi,

The easiest approach would be to implement ICustomTypeDescriptor. This way you won't need to modify RadGrid in any way.
ICustomTypeDescriptor Interface (System.ComponentModel)

Regards,
Daniel
the Telerik team

[Avidan]

Daniel,

My business objects do implements ICustomTypeDescriptor, I also followed the guidelines Tips when binding to custom collections. The problem is that I am actually cheating the binding control (in my case the RadGrid) by telling him that my object have a property which does not exist (i.e. Field(parm) as object) and I want to know how the Grid is using the GetValue/SetValue methods (of the ICustomTypedProperty interface) instaed of trying to find the virtual property?

Another alternative is to use Template columns in RadGrid,where the content of each column is a Label control that hook the ondatabinding event to use ICustomTypedProperty GetValue/SetValue methods , but with that solution I am unable to sort and filter grid items

Avidan

[Daniel]

Hello Avidan,

The problem is that I am actually cheating the binding control (in my case the RadGrid) by telling him that my object have a property which does not exist
Yes, this is the way the custom type descriptor should work in your scenario. This will allow you use the built-in sorting, filtering, grouping, etc. Since RadGrid doesn't know the real type of the data items in your datasource, the only way to retrieve the bindable properties is to use reflection. RadGrid extracts the property descriptors for the given types and uses these descriptors to fetch the corresponding values.

I want to know how the Grid is using the GetValue/SetValue methods (of the ICustomTypedProperty interface)
As explained above, RadGrid gets the custom property descriptor of the given properties and calls its GetValue / SetValue methods.

Another alternative is to use Template columns in RadGrid
I purposely directed you towards the ICustomTypeDesciptor - if you don't have valid data fields, most of the built-in functions won't work.

Best regards,
Daniel
the Telerik team

[Avidan]

Hi Daniel

See the attached example; MyProduct is my business object, I'm using RadGrid advanced binding to a list of (MyProduct);  All the field values are displayed correctlly, however when I try to filter/sort or groupby, I get the following error message "No property or field 'xxx' exists in type 'MyProduct'

No property or field 'NAME' exists in type 'MyProduct'
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: Telerik.Web.UI.ParseException: No property or field 'NAME' exists in type 'MyProduct'

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:


[ParseException: No property or field 'NAME' exists in type 'MyProduct']
   Telerik.Web.UI.ExpressionParser.ParseMemberAccess(Type type, Expression instance) +1526
   Telerik.Web.UI.ExpressionParser.ParseIdentifier() +549
   Telerik.Web.UI.ExpressionParser.ParsePrimaryStart() +65
   Telerik.Web.UI.ExpressionParser.ParsePrimary() +36
   Telerik.Web.UI.ExpressionParser.ParseUnary() +365
   Telerik.Web.UI.ExpressionParser.ParseMultiplicative() +54
   Telerik.Web.UI.ExpressionParser.ParseAdditive() +54
   Telerik.Web.UI.ExpressionParser.ParseComparison() +57
   Telerik.Web.UI.ExpressionParser.ParseLogicalAnd() +49
   Telerik.Web.UI.ExpressionParser.ParseLogicalOr() +49
   Telerik.Web.UI.ExpressionParser.ParseExpression() +60
   Telerik.Web.UI.ExpressionParser.ParseOrdering() +80
   Telerik.Web.UI.GridDynamicQueryable.OrderBy(IQueryable source, String ordering, Object[] values) +420
   Telerik.Web.UI.GridDataTableFromEnumerable.FillData35() +3922
   Telerik.Web.UI.GridDataTableFromEnumerable.FillData() +1037
   Telerik.Web.UI.GridResolveEnumerable.Initialize() +55
   Telerik.Web.UI.GridResolveEnumerable.EnsureInitialized() +40
   Telerik.Web.UI.GridResolveEnumerable.get_DataTable() +31
   Telerik.Web.UI.GridEnumerableFromDataView..ctor(GridTableView owner, IEnumerable enumerable, Boolean CaseSensitive, Boolean autoGenerateColumns, GridColumnCollection presentColumns, String[] additionalField, Boolean retrieveAllFields) +222
   Telerik.Web.UI.GridDataSourceHelper.CreateGridEnumerable(GridTableView owner, IEnumerable enumerable, Boolean caseSensitive, Boolean autoGenerateColumns, GridColumnCollection presentColumns, String[] additionalField, Boolean retrieveAllFields) +155
   Telerik.Web.UI.GridDataSourceHelper.GetResolvedDataSource(GridTableView owner, Object dataSource, String dataMember, Boolean caseSensitive, Boolean autoGenerateColumns, GridColumnCollection presentColumns, String[] additionalField, Boolean retrieveAllFields) +556
   Telerik.Web.UI.GridTableView.get_ResolvedDataSource() +219
   Telerik.Web.UI.GridTableView.CreateChildControls(IEnumerable dataSource, Boolean useDataSource) +73
   System.Web.UI.WebControls.CompositeDataBoundControl.PerformDataBinding(IEnumerable data) +57
   System.Web.UI.WebControls.DataBoundControl.OnDataSourceViewSelectCallback(IEnumerable data) +114
   System.Web.UI.DataSourceView.Select(DataSourceSelectArguments arguments, DataSourceViewSelectCallback callback) +31
   System.Web.UI.WebControls.DataBoundControl.PerformSelect() +142
   Telerik.Web.UI.GridTableView.PerformSelect() +38
   System.Web.UI.WebControls.BaseDataBoundControl.DataBind() +73
   Telerik.Web.UI.GridTableView.DataBind() +353
   Telerik.Web.UI.GridSortCommandEventArgs.ExecuteCommand(Object source) +326
   Telerik.Web.UI.RadGrid.OnBubbleEvent(Object source, EventArgs e) +191
   System.Web.UI.Control.RaiseBubbleEvent(Object source, EventArgs args) +37
   Telerik.Web.UI.GridItem.OnBubbleEvent(Object source, EventArgs e) +61
   System.Web.UI.Control.RaiseBubbleEvent(Object source, EventArgs args) +37
   Telerik.Web.UI.GridItem.OnBubbleEvent(Object source, EventArgs e) +165
   System.Web.UI.Control.RaiseBubbleEvent(Object source, EventArgs args) +37
   System.Web.UI.WebControls.LinkButton.OnCommand(CommandEventArgs e) +118
   System.Web.UI.WebControls.LinkButton.RaisePostBackEvent(String eventArgument) +135
   System.Web.UI.WebControls.LinkButton.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +10
   System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +13
   System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +175
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1565

MyProduct Busines Object

 

Imports System
Imports System.ComponentModel
Imports System.Reflection

Public Class MyProduct
    Inherits Object
    Implements ICustomTypeDescriptor

    ' MyProduct object has three virtual properties: ID, NAME and PRICE

    ' _values keep the object property values
    ' _field keep a collection of FieldPropertyDescriptors

    ' NOTICE:
    ' Whenever a programmer is trying to set a value which is not exits in _values array,
    ' a new FieldPropertyDescriptor is added to _fields

    Private _values As New Dictionary(Of String, Object)
    Private _fields As New PropertyDescriptorCollection(Nothing)

    Public Property Field(ByVal fieldname As String) As Object
        Get
            If _values.Keys.Contains(fieldname) Then
                Return _values(fieldname)
            Else
                Return Nothing
            End If
        End Get
        Set(ByVal value As Object)
            If _values.Keys.Contains(fieldname) Then
                _values(fieldname) = value
            Else
                _values.Add(fieldname, value)
                Me.AddFieldPropertyDescriptor(fieldname)
            End If
        End Set
    End Property
#Region "Private Methods"
    Private Sub AddFieldPropertyDescriptor(ByVal fieldname As String)
        Dim fpd As FieldPropertyDescriptor
        Select Case fieldname
            Case "ID"
                Dim field As New Field("ID", "ProductID", System.Type.GetType("string", False, True), 10, False)
                fpd = New FieldPropertyDescriptor(field)
                _fields.Add(fpd)
            Case "NAME"
                Dim field As New Field("NAME", "Product Name", System.Type.GetType("string", False, True), 50, False)
                fpd = New FieldPropertyDescriptor(field)
                _fields.Add(fpd)
            Case "PRICE"
                Dim field As New Field("PRICE", "Product Price", System.Type.GetType("integer", False, True), 50, True)
                fpd = New FieldPropertyDescriptor(field)
                _fields.Add(fpd)
            Case Else
                ' do nothing
        End Select

    End Sub

#End Region
#Region "ICustomTypeDescriptor"
    Public Function GetAttributes() As System.ComponentModel.AttributeCollection Implements System.ComponentModel.ICustomTypeDescriptor.GetAttributes
        Return New System.ComponentModel.AttributeCollection(Nothing)

    End Function

    Public Function GetClassName() As String Implements System.ComponentModel.ICustomTypeDescriptor.GetClassName
        Return Nothing
    End Function

    Public Function GetComponentName() As String Implements System.ComponentModel.ICustomTypeDescriptor.GetComponentName
        Return Nothing
    End Function

    Public Function GetConverter() As System.ComponentModel.TypeConverter Implements System.ComponentModel.ICustomTypeDescriptor.GetConverter
        Return Nothing
    End Function

    Public Function GetDefaultEvent() As System.ComponentModel.EventDescriptor Implements System.ComponentModel.ICustomTypeDescriptor.GetDefaultEvent
        Return Nothing
    End Function

    Public Function GetDefaultProperty() As System.ComponentModel.PropertyDescriptor Implements System.ComponentModel.ICustomTypeDescriptor.GetDefaultProperty
        Return Nothing
    End Function

    Public Function GetEditor(ByVal editorBaseType As System.Type) As Object Implements System.ComponentModel.ICustomTypeDescriptor.GetEditor
        Return Nothing
    End Function

    Public Function GetEvents() As System.ComponentModel.EventDescriptorCollection Implements System.ComponentModel.ICustomTypeDescriptor.GetEvents
        Return New EventDescriptorCollection(Nothing)

    End Function

    Public Function GetEvents(ByVal attributes() As System.Attribute) As System.ComponentModel.EventDescriptorCollection Implements System.ComponentModel.ICustomTypeDescriptor.GetEvents
        Return New EventDescriptorCollection(Nothing)

    End Function

    Public Function GetProperties() As System.ComponentModel.PropertyDescriptorCollection Implements System.ComponentModel.ICustomTypeDescriptor.GetProperties
        Return GetProperties(Nothing)

    End Function

    Public Function GetProperties(ByVal attributes() As System.Attribute) As System.ComponentModel.PropertyDescriptorCollection Implements System.ComponentModel.ICustomTypeDescriptor.GetProperties
        Return _fields
    End Function

    Public Function GetPropertyOwner(ByVal pd As System.ComponentModel.PropertyDescriptor) As Object Implements System.ComponentModel.ICustomTypeDescriptor.GetPropertyOwner
        Return Me
    End Function
#End Region

End Class

I use custom PropertyDescriptor that provides field infromation using the Field object, code blocked are attached:

FieldPropertyDescriptor Object:

Imports System.ComponentModel
Imports System.Reflection

Public Class FieldPropertyDescriptor
    Inherits PropertyDescriptor

    Private _field As Field

    Public Sub New(ByVal field As Field)
        MyBase.New(field.Name, Nothing)
        _field = field
    End Sub

#Region "PropertyDescriptor Overrides"

#Region "Properties"

    Public Overrides ReadOnly Property Converter() As System.ComponentModel.TypeConverter
        Get
            Return MyBase.Converter
        End Get
    End Property
    Public Overrides ReadOnly Property DisplayName() As String
        Get
            Return _field.DisplayName
        End Get
    End Property

    Public Overrides ReadOnly Property IsReadOnly() As Boolean
        Get
            Return False
        End Get
    End Property
    Public Overrides ReadOnly Property Name() As String
        Get
            Return _field.Name
        End Get
    End Property

    Public Overrides ReadOnly Property PropertyType() As System.Type
        Get
            Return _field.Type
        End Get
    End Property


#End Region

#Region "Methods - Public"
    Public Overrides Function CanResetValue(ByVal component As Object) As Boolean
        Return False
    End Function
    Public Overrides ReadOnly Property ComponentType() As System.Type
        Get
            Return Me.PropertyType
        End Get
    End Property

    Public Overrides Function GetValue(ByVal component As Object) As Object
        Dim prod As MyProduct = TryCast(component, MyProduct)
        Return prod.Field(_field.Name)

    End Function

    Public Overrides Sub ResetValue(ByVal component As Object)
        Throw (New NotImplementedException())
    End Sub

    Public Overrides Sub SetValue(ByVal component As Object, ByVal value As Object)
        Dim prod As MyProduct = TryCast(component, MyProduct)
        prod.Field(_field.Name) = value
    End Sub

    Public Overrides Function ShouldSerializeValue(ByVal component As Object) As Boolean
        Return False
    End Function


#End Region

#End Region
End Class

Field object:

Imports System
Imports System.Collections.Generic
Imports System.Text
Public Class Field
#Region "Data Members"
    Private _columnName As String
    Private _columnDisplayName As String
    Private _columnType As Type
    Private _length As Integer
    Private _allowNull As Boolean
#End Region

#Region "Constructors"
    Public Sub New()

    End Sub
    Public Sub New(ByVal Name As String, ByVal DisplayName As String, ByVal Type As Type, ByVal length As Integer, ByVal allowNull As Boolean)
        _columnName = Name
        _columnDisplayName = DisplayName
        _columnType = Type
        _length = length
        _allowNull = allowNull
    End Sub
    Public Sub New(ByVal field As Field)
        _columnName = field._columnName
        _columnDisplayName = field._columnDisplayName
        _columnType = field._columnType
        _length = field._length
        _allowNull = field._allowNull
    End Sub
#End Region
#Region "Properties"
    Public Property Name() As String
        Get
            Return _columnName
        End Get
        Set(ByVal value As String)
            _columnName = value
        End Set
    End Property
    Public Property DisplayName() As String
        Get
            Return _columnDisplayName
        End Get
        Set(ByVal value As String)
            _columnDisplayName = value
        End Set
    End Property
    Public Property Type() As Type
        Get
            Return _columnType
        End Get
        Set(ByVal value As Type)
            _columnType = value
        End Set
    End Property
    Public Property Length() As Integer
        Get
            Return _length
        End Get
        Set(ByVal value As Integer)
            _length = value
        End Set
    End Property
    Public Property AllowNull() As Boolean
        Get
            Return _allowNull
        End Get
        Set(ByVal value As Boolean)
            _allowNull = value
        End Set
    End Property
#End Region
End Class

[Daniel]

Hello Avi,

Please set EnableLinqExpressions="false" as shown below:

<telerik:RadGrid ID="RadGrid1" runat="server" EnableLinqExpressions="false">
...
</telerik:RadGrid>

Let me know if the problem still persists.

Best regards,
Daniel
the Telerik team

[Avidan]

Daniel,

Filtering by column does not throw any exception but the filter is not working.

When sorting by column the following exception is thrown:

Server Error in '/' Application.
--------------------------------------------------------------------------------

Cannot find column NAME.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.IndexOutOfRangeException: Cannot find column NAME.

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:


[IndexOutOfRangeException: Cannot find column NAME.]
   System.Data.DataTable.ParseSortString(String sortString) +4822718
   System.Data.DataView.CheckSort(String sort) +32
   System.Data.DataView.set_Sort(String value) +128
   Telerik.Web.UI.GridEnumerableFromDataView.PerformTransformation() +3788
   Telerik.Web.UI.GridEnumerableFromDataView.TransformEnumerable() +21
   Telerik.Web.UI.GridTableView.GetEnumerator(Boolean useDataSource, GridEnumerableBase resolvedDataSource, ArrayList dataKeysArray) +105
   Telerik.Web.UI.GridTableView.CreateControlHierarchy(Boolean useDataSource) +433
   Telerik.Web.UI.GridTableView.CreateChildControls(IEnumerable dataSource, Boolean useDataSource) +498
   System.Web.UI.WebControls.CompositeDataBoundControl.PerformDataBinding(IEnumerable data) +57
   System.Web.UI.WebControls.DataBoundControl.OnDataSourceViewSelectCallback(IEnumerable data) +114
   System.Web.UI.DataSourceView.Select(DataSourceSelectArguments arguments, DataSourceViewSelectCallback callback) +31
   System.Web.UI.WebControls.DataBoundControl.PerformSelect() +142
   Telerik.Web.UI.GridTableView.PerformSelect() +16
   System.Web.UI.WebControls.BaseDataBoundControl.DataBind() +73
   Telerik.Web.UI.GridTableView.DataBind() +221
   Telerik.Web.UI.GridSortCommandEventArgs.ExecuteCommand(Object source) +126
   Telerik.Web.UI.RadGrid.OnBubbleEvent(Object source, EventArgs e) +134
   System.Web.UI.Control.RaiseBubbleEvent(Object source, EventArgs args) +37
   Telerik.Web.UI.GridItem.OnBubbleEvent(Object source, EventArgs e) +38
   System.Web.UI.Control.RaiseBubbleEvent(Object source, EventArgs args) +37
   Telerik.Web.UI.GridItem.OnBubbleEvent(Object source, EventArgs e) +115
   System.Web.UI.Control.RaiseBubbleEvent(Object source, EventArgs args) +37
   System.Web.UI.WebControls.LinkButton.OnCommand(CommandEventArgs e) +118
   System.Web.UI.WebControls.LinkButton.RaisePostBackEvent(String eventArgument) +135
   System.Web.UI.WebControls.LinkButton.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +10
   System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +13
   System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +175
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1565

when grouping by column the following exception is thrown:

Server Error in '/' Application.
--------------------------------------------------------------------------------

Field NAME not found in the source table. Please check the expression syntax.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: Telerik.Web.UI.GridGroupByException: Field NAME not found in the source table. Please check the expression syntax.

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:


[GridGroupByException: Field NAME not found in the source table. Please check the expression syntax.]
   Telerik.Web.UI.GridDataSetHelper.CreateGroupByTable(DataTable SourceTable, GridTableView view) +376
   Telerik.Web.UI.GridEnumerableFromDataView.PerformTransformation() +2820
   Telerik.Web.UI.GridEnumerableFromDataView.TransformEnumerable() +21
   Telerik.Web.UI.GridTableView.GetEnumerator(Boolean useDataSource, GridEnumerableBase resolvedDataSource, ArrayList dataKeysArray) +105
   Telerik.Web.UI.GridTableView.CreateControlHierarchy(Boolean useDataSource) +433
   Telerik.Web.UI.GridTableView.CreateChildControls(IEnumerable dataSource, Boolean useDataSource) +498
   System.Web.UI.WebControls.CompositeDataBoundControl.PerformDataBinding(IEnumerable data) +57
   System.Web.UI.WebControls.DataBoundControl.OnDataSourceViewSelectCallback(IEnumerable data) +114
   System.Web.UI.DataSourceView.Select(DataSourceSelectArguments arguments, DataSourceViewSelectCallback callback) +31
   System.Web.UI.WebControls.DataBoundControl.PerformSelect() +142
   Telerik.Web.UI.GridTableView.PerformSelect() +16
   System.Web.UI.WebControls.BaseDataBoundControl.DataBind() +73
   Telerik.Web.UI.GridTableView.DataBind() +221
   Telerik.Web.UI.GridTableView.BindAllInHierarchyLevel() +52
   Telerik.Web.UI.RadGrid.RaisePostBackEvent(String eventArgument) +5114
   System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +13
   System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +175
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1565

Avidan

[Daniel]

Hello Avi,

Can you please post the rest of the code so that we can construct a fully runnable demo based on your scenario?

Regards,
Daniel
the Telerik team

[Avidan]

Daniel,

enclose aspx and it's code beind:

Aspx:

<body>
    <form id="form1" runat="server">
    <telerik:RadScriptManager ID="RadScriptManager1" runat="server">
    </telerik:RadScriptManager>
    <telerik:RadGrid ID="RadGrid1" runat="server" AllowFilteringByColumn="True"
        AllowPaging="True" AllowSorting="True" AutoGenerateColumns="False"
        GridLines="None" ShowGroupPanel="True" Skin="Outlook"
        AutoGenerateDeleteColumn="True" AutoGenerateEditColumn="True" EnableLinqExpressions ="false">
<MasterTableView>
<RowIndicatorColumn>
<HeaderStyle Width="20px"></HeaderStyle>
</RowIndicatorColumn>

<ExpandCollapseColumn>
<HeaderStyle Width="20px"></HeaderStyle>
</ExpandCollapseColumn>
    <Columns>
        <telerik:GridBoundColumn DataField="ID" HeaderText="ID" UniqueName="column" SortExpression="ID" >
        </telerik:GridBoundColumn>
        <telerik:GridBoundColumn DataField="NAME" HeaderText="Name"
            UniqueName="column1">
        </telerik:GridBoundColumn>
        <telerik:GridBoundColumn DataField="PRICE" DataType="System.Int32"
            HeaderText="Price" UniqueName="column2">
        </telerik:GridBoundColumn>
    </Columns>
</MasterTableView>
        <ClientSettings AllowDragToGroup="True">
            <Selecting AllowRowSelect="True" />
            <Scrolling AllowScroll="True" UseStaticHeaders="True" />
        </ClientSettings>
    </telerik:RadGrid>
    <div>

    </div>
    </form>
</body>

Code behind:

Protected Sub RadGrid1_NeedDataSource(ByVal source As Object, ByVal e As Telerik.Web.UI.GridNeedDataSourceEventArgs) Handles RadGrid1.NeedDataSource
        Dim list As New MyProductsList
        Me.RadGrid1.DataSource = list.GetLists
    End Sub

[Daniel]

Hello Avi,

Thank you for the sample code. Please download the attached project and let me know whether it works properly on your end.

Regards,
Daniel
the Telerik team

[Avidan]

Daniel,

it works properly !!!

Now tell me your secrets, what have you done to make it work.

Avidan

[Ron]

I am  trying to get the same strategy for 'dynamic grids' implemented. I have one issue though. I am trying to get the example above working with a linq datasource because i want the data to be cached. So I have changed the default.aspx.cs into:

public partial class Default : System.Web.UI.Page
{
    protected void Page_Init(object sender, EventArgs e)
    {
        LinqDataSource linqDataSource = new LinqDataSource();
        linqDataSource.Selecting += new EventHandler<LinqDataSourceSelectEventArgs>(LinqDataSource_Selecting);
        linqDataSource.Selected += new EventHandler<LinqDataSourceStatusEventArgs>(LinqDataSource_Selected);
        this.RadGrid1.DataSource = linqDataSource;
    }

    void LinqDataSource_Selecting(object sender, LinqDataSourceSelectEventArgs e)
    {
        if (Cache["MyData"] != null)
        {
            e.Result = Cache["MyData"];
        }
        else
        {
            MyProductList list = new MyProductList();
            e.Result = list.GetLists().AsQueryable();
        }
    }

    void LinqDataSource_Selected(object sender, LinqDataSourceStatusEventArgs e)
    {
        if (Cache["MyData"] == null && e.Result != null)
        {
            Cache["MyData"] = e.Result;
        }
    }
}

The problem now is that sorting and grouping produces the following error. Any thoughts on getting the example going with linq datasource caching without loosing the sorting and grouping abilities? is an alternative caching strategy required?

[GridGroupByException: Field NAME not found in the source table. Please check the expression syntax.] Telerik.Web.UI.GridDataSetHelper.CreateGroupByTable(DataTable SourceTable, GridTableView view) +419 Telerik.Web.UI.GridEnumerableFromDataView.PerformTransformation() +3009 Telerik.Web.UI.GridEnumerableFromDataView.TransformEnumerable() +18 Telerik.Web.UI.GridTableView.GetEnumerator(Boolean useDataSource, GridEnumerableBase resolvedDataSource, ArrayList dataKeysArray) +122 Telerik.Web.UI.GridTableView.CreateControlHierarchy(Boolean useDataSource) +452 Telerik.Web.UI.GridTableView.CreateChildControls(IEnumerable dataSource, Boolean useDataSource) +659 System.Web.UI.WebControls.CompositeDataBoundControl.PerformDataBinding(IEnumerable data) +66 System.Web.UI.WebControls.DataBoundControl.OnDataSourceViewSelectCallback(IEnumerable data) +128 System.Web.UI.DataSourceView.Select(DataSourceSelectArguments arguments, DataSourceViewSelectCallback callback) +33 System.Web.UI.WebControls.DataBoundControl.PerformSelect() +143 Telerik.Web.UI.GridTableView.PerformSelect() +16 System.Web.UI.WebControls.BaseDataBoundControl.DataBind() +74 Telerik.Web.UI.GridTableView.DataBind() +256 Telerik.Web.UI.GridTableView.BindAllInHierarchyLevel() +52 Telerik.Web.UI.RadGrid.RaisePostBackEvent(String eventArgument) +8143 System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +13 System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +176 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +5563

[Daniel]

Hello Ron,

Could you please isolate the problem in a runnable project (as simple as possible) so that we can debug the code locally? You can attach the code to a regular support ticket.
Isolating a problem in a sample project

Thank you for your understanding.

Best regards,
Daniel
the Telerik team

[Andrey]

Hi!
Could you point me to proper way of handling custom sorting in RadGrid?

With markup as following -

<telerik:RadGrid ID="someGrid" runat="server"
                    AllowSorting="True"
                    OnSortCommand="someGrid_SortCommand">
             <MasterTableView>
              <Columns>
                    <telerik:GridHyperLinkColumn
                        SortExpression="someCustomSortExpression"
                        DataTextField="someField"/>
              </Columns>
             </MasterTableView>
</telerik:RadGrid>

I keep receiving exception "Cannot find column someCustomSortExpression" or ("no property or field someCustomSortExpression found" if column was created dynamically, which is ultimately a goal)

Thanks!

[Kiara]

Try to modify the code as follows:

<telerik:RadGrid ID="someGrid" runat="server"

                    AllowSorting="True"

                    OnSortCommand="someGrid_SortCommand">

             <MasterTableView>

              <Columns>

                    <telerik:GridHyperLinkColumn

                        SortExpression="someField"

                        DataTextField="someField"/>

              </Columns>

             </MasterTableView>

</telerik:RadGrid>

The SortExpression value should match the value of the field set through the DataTextField property of the hyperlink column.

-Kiara

[Andrey]

Hi, Kiara!
Unfortunately, it makes no sense to use already defined property for SortExpression in this snippet, as topic specifically refers to "dynamic/undeclared properties"

Andrey. 

[Andrey]

setting Telerik.Web.UI.GridSortCommandEventArgs.Canceled = true in custom handler appeared to be an answer