An item with the same key has already been added.

[Larry]

I have a RadGrid in a FormView.  I bind to the FormView with an object datasource. The grid binds to a List that is a property of the object datasource object.   The first time loading the page (in Edit Mode) which retrieves a record everything works fine and the grid binds to the List.    When I hit Submit to save everything I get the error.  We are running 2010.1.415.35

                    <telerik:RadGrid
                        ID="RegGrid"
                        runat="server"
                        Skin="Windows7"
                        BorderStyle="None"
                        GridLines="None"
                        Width="650px"
                        PageSize="20"
                        AllowFilteringByColumn="true"
                        AllowSorting="True"
                        ShowFooter="True"
                        AllowPaging="True"
                        AutoGenerateColumns="False"
                        EnableLinqExpressions="false"
                        AllowAutomaticInserts="false"
                        AllowAutomaticUpdates="false"
                        AllowAutomaticDeletes="false"
                        OnItemCreated="RegGrid_ItemCreated"
                        OnItemCommand="RegGrid_ItemCommand"
                        OnItemDataBound="RegGrid_ItemDataBound"
                        OnDeleteCommand="RegGrid_DeleteCommand"
                        OnInsertCommand="RegGrid_InsertCommand"
                        OnUpdateCommand="RegGrid_UpdateCommand"
                        OnNeedDataSource="RegGrid_NeedDataSource">
                        <ClientSettings>
                            <Selecting AllowRowSelect="false" />
                        </ClientSettings>
                        <MasterTableView
                            DataKeyNames="regRequest,item"
                            EditMode="InPlace"
                            AllowFilteringByColumn="True"
                            ShowFooter="True"
                            CommandItemDisplay="Top"
                            InsertItemPageIndexAction="ShowItemOnCurrentPage"
                            CommandItemSettings-AddNewRecordText="Add Package"
                            ItemStyle-VerticalAlign="top"
                            AlternatingItemStyle-VerticalAlign="top"
                            HeaderStyle-HorizontalAlign="Center">
                            <Columns>
                                <telerik:GridTemplateColumn AllowFiltering="false">
                                    <ItemTemplate>
                                        <asp:LinkButton ID="LinkButton2" runat="server" CommandName="Edit">Edit</asp:LinkButton>
                                        <asp:LinkButton ID="LinkButton1" runat="server" CommandName="Delete" OnClientClick="javascript:return confirm('Delete this Reg Item?')">Delete</asp:LinkButton>
                                    </ItemTemplate>
                                    <EditItemTemplate>
                                        <asp:LinkButton ID="LinkButton3" runat="server" Text='<%# ((GridItem)Container).OwnerTableView.IsItemInserted? "Insert" : "Update" %>'
                                            CommandName='<%# ((GridItem)Container).OwnerTableView.IsItemInserted? "PerformInsert" : "Update" %>'></asp:LinkButton>
                                        <asp:LinkButton ID="LinkButton4" runat="server" CommandName="Cancel">Cancel</asp:LinkButton>
                                    </EditItemTemplate>
                                </telerik:GridTemplateColumn>
                                <telerik:GridBoundColumn DataField="regRequest" Visible="false" />
                                <telerik:GridDropDownColumn UniqueName="ddcRegItems" DataField="item" ListTextField="name" ListValueField="item"
                                     DataSourceID="sqlRegRequestItem" HeaderText="Reg Item" DropDownControlType="DropDownList" EmptyListItemText="- Select A Package -" EmptyListItemValue="0" />
                                <telerik:GridBoundColumn DataField="quantity" HeaderText="Qty" DataFormatString="{0:n}" />
                                <telerik:GridBoundColumn DataField="price" HeaderText="Price" DataFormatString="{0:C}" ReadOnly="true" />
                                <telerik:GridCalculatedColumn HeaderText="Total (USD)" UniqueName="ExtendedPrice"
                                    DataType="System.Double" DataFields="quantity, price" Expression="{0}*{1}" FooterText="Total : "
                                    Aggregate="Sum" DataFormatString="{0:C}" />
                            </Columns>
                        </MasterTableView>
                        <PagerStyle Mode="NextPrevAndNumeric" />
                    </telerik:RadGrid>

    protected void RegGrid_NeedDataSource(object source, Telerik.Web.UI.GridNeedDataSourceEventArgs e)
    {

        RIM.Event.Resources.Regcode.Request _request = (RIM.Event.Resources.Regcode.Request)(Session["Request"]);
        if (_request != null)
        {
            // SELECT NON-DELETED ITEMS
            List<RegItem> _regitems = _request.regItems.FindAll(p => p.deleted != true);

            ((RadGrid)source).DataSource = _regitems;
        }
    }

[Larry]

I forgot to list the Stack Trace;

[ArgumentException: An item with the same key has already been added.]
   System.ThrowHelper.ThrowArgumentException(ExceptionResource resource) +51
   System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add) +7464444
   System.Collections.Generic.Dictionary`2.Add(TKey key, TValue value) +11
   Telerik.Web.UI.GridDataTableFromEnumerable.FillData() +5080
   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) +221
   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.RadGrid.DataBind() +165
   System.Web.UI.Control.DataBindChildren() +211
   System.Web.UI.Control.DataBind(Boolean raiseOnDataBinding) +102
   System.Web.UI.Control.DataBind() +15
   System.Web.UI.Control.DataBindChildren() +211
   System.Web.UI.Control.DataBind(Boolean raiseOnDataBinding) +102
   System.Web.UI.Control.DataBind() +15
   System.Web.UI.Control.DataBindChildren() +211
   System.Web.UI.Control.DataBind(Boolean raiseOnDataBinding) +102
   System.Web.UI.Control.DataBind() +15
   System.Web.UI.Control.DataBindChildren() +211
   System.Web.UI.Control.DataBind(Boolean raiseOnDataBinding) +102
   System.Web.UI.Control.DataBind() +15
   System.Web.UI.Control.DataBindChildren() +211
   System.Web.UI.Control.DataBind(Boolean raiseOnDataBinding) +102
   System.Web.UI.Control.DataBind() +15
   System.Web.UI.Control.DataBindChildren() +211
   System.Web.UI.Control.DataBind(Boolean raiseOnDataBinding) +102
   System.Web.UI.WebControls.FormView.CreateChildControls(IEnumerable dataSource, Boolean dataBinding) +1461
   System.Web.UI.WebControls.CompositeDataBoundControl.PerformDataBinding(IEnumerable data) +57
   System.Web.UI.WebControls.FormView.PerformDataBinding(IEnumerable data) +12
   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
   System.Web.UI.WebControls.BaseDataBoundControl.DataBind() +73
   System.Web.UI.WebControls.FormView.DataBind() +4
   System.Web.UI.WebControls.BaseDataBoundControl.EnsureDataBound() +82
   System.Web.UI.WebControls.FormView.EnsureDataBound() +166
   System.Web.UI.WebControls.BaseDataBoundControl.OnPreRender(EventArgs e) +22
   System.Web.UI.Control.PreRenderRecursiveInternal() +80
   System.Web.UI.Control.PreRenderRecursiveInternal() +171
   System.Web.UI.Control.PreRenderRecursiveInternal() +171
   System.Web.UI.Control.PreRenderRecursiveInternal() +171
   System.Web.UI.Control.PreRenderRecursiveInternal() +171
   System.Web.UI.Control.PreRenderRecursiveInternal() +171
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +842

[Larry]

setting EnableLinqExpressions to true fixed this problem.

[Miguel]

Hi Larry,

I have the same problem and if I set EnableLinqExpressions  to true I get a new error:
Unable to cast object of type 'DynamicClass1' to type 'OES.Entity.OES_GeneracionGas'
and 'OES.Entity.OES_GeneracionGas' is a custom object.

Do you know what this is happening?

Thanks!
Miguel

[Miguel]

Hi, can anyone help me please?

Thanks!
Miguel

[Meera]

set
RegGrid.DataSource=null ;
before rebinding.