Hi Guys,

I am getting this error and not sure why it's throwing this error. Are you able to shed any light? Below is the actual stack trace and also the function itself where this error is thrown:

Object reference not set to an instance of an object. Exception Type: System.NullReferenceException Source: SD.LLBLGen.Pro.ORMSupportClasses.NET20

Error Stack Trace: at SD.LLBLGen.Pro.ORMSupportClasses.EntityNameFinder.Traverse(IEntityFieldCore field) 
at SD.LLBLGen.Pro.ORMSupportClasses.QueryApiObjectTraverser.TraverseExpressionOperand(IExpressionElement operand) 
at SD.LLBLGen.Pro.ORMSupportClasses.QueryApiObjectTraverser.Traverse(IExpression objectToTraverse) 
at SD.LLBLGen.Pro.ORMSupportClasses.QueryApiObjectTraverser.Traverse(Object objectToTraverse) 
at SD.LLBLGen.Pro.ORMSupportClasses.QueryApiObjectTraverser.TraversePredicate(IPredicate objectToTraverse) 
at SD.LLBLGen.Pro.ORMSupportClasses.QueryApiObjectTraverser.Traverse(IPredicate objectToTraverse) 
at SD.LLBLGen.Pro.ORMSupportClasses.QueryApiObjectTraverser.Traverse(IPredicate objectToTraverse) 
at SD.LLBLGen.Pro.ORMSupportClasses.QueryApiObjectTraverser.Traverse(IPredicate objectToTraverse) 
at SD.LLBLGen.Pro.ORMSupportClasses.QueryApiObjectTraverser.Traverse(IPredicate objectToTraverse) 
at SD.LLBLGen.Pro.ORMSupportClasses.PersistenceCore.DetermineInheritanceRelations(IEnumerable fields, IRelationCollection relations, IPredicate filter, IInheritanceInfoProvider inheritanceProvider, UniqueValueList`1 outerScopeAliases) 
at SD.LLBLGen.Pro.ORMSupportClasses.PersistenceCore.AddInheritanceRelatedElementsToQueryElementsForDynamicList(InheritanceHierarchyType hierarchyType, IList fields, IPredicateExpression filter, IRelationCollection relations, IInheritanceInfoProvider infoProvider, String forEntityName) 
at SD.LLBLGen.Pro.ORMSupportClasses.DaoBase.CreateQueryFromElements(ITransaction transactionToUse, IEntityFields fields, IPredicate filter, IRelationCollection relations, Int32 maxNumberOfItemsToReturn, ISortExpression sortClauses, IGroupByCollection groupByClause, Boolean allowDuplicates, Int32 pageNumber, Int32 pageSize) 
at SD.LLBLGen.Pro.ORMSupportClasses.DaoBase.PerformGetMultiAsDataTableAction(IEntityFields fieldsToReturn, DataTable tableToFill, Int64 maxNumberOfItemsToReturn, ISortExpression sortClauses, IPredicate selectFilter, IRelationCollection relations, Boolean allowDuplicates, IGroupByCollection groupByClause, ITransaction transactionToUse, Int32 pageNumber, Int32 pageSize) 
at SD.LLBLGen.Pro.ORMSupportClasses.DaoBase.GetMultiAsDataTable(IEntityFields fieldsToReturn, DataTable tableToFill, Int64 maxNumberOfItemsToReturn, ISortExpression sortClauses, IPredicate selectFilter, IRelationCollection relations, Boolean allowDuplicates, IGroupByCollection groupByClause, ITransaction transactionToUse, Int32 pageNumber, Int32 pageSize) 
at DSC.STARS.DAL.TypedViewClasses.SdsearchTypedView.Fill(Int64 maxNumberOfItemsToReturn, ISortExpression sortClauses, Boolean allowDuplicates, IPredicate selectFilter, ITransaction transactionToUse, IGroupByCollection groupByClause, Int32 pageNumber, Int32 pageSize) in C:\TFSSourceCode\DSC.STARS\Main\DSC.STARS.DAL\TypedViewClasses\SdsearchTypedView.vb:line 201 
at DSC.STARS.DAL.TypedViewClasses.SdsearchTypedView.Fill(Int64 maxNumberOfItemsToReturn, ISortExpression sortClauses, Boolean allowDuplicates, IPredicate selectFilter) in C:\TFSSourceCode\DSC.STARS\Main\DSC.STARS.DAL\TypedViewClasses\SdsearchTypedView.vb:line 149 
at DSC.STARS.BAL.Referral.SearchReferral(PredicateExpression Filter, SortExpression Sort, Transaction Transaction) in C:\TFSSourceCode\DSC.STARS\Main\DSC.STARS.BAL\Referral.vb:line 385 
at DSC.STARS.WEB.SDSearchInd.GetReferralData() in C:\TFSSourceCode\DSC.STARS\Main\DSC.STARS.WEB\SDSearchInd.aspx.vb:line 153 
at DSC.STARS.WEB.SDSearchInd.dgReferrals_NeedDataSource(Object source, GridNeedDataSourceEventArgs e) in C:\TFSSourceCode\DSC.STARS\Main\DSC.STARS.WEB\SDSearchInd.aspx.vb:line 99 
at Telerik.Web.UI.RadGrid.OnNeedDataSource(GridNeedDataSourceEventArgs e) 
at Telerik.Web.UI.RadGrid.ObtainDataSource(GridRebindReason rebindReason, Boolean IsBoundUsingDataSourceId) 
at Telerik.Web.UI.RadGrid.AutoDataBind(GridRebindReason rebindReason) 
at Telerik.Web.UI.RadGrid.OnLoad(EventArgs e) 
at System.Web.UI.Control.LoadRecursive() 
at System.Web.UI.Control.LoadRecursive() 
at System.Web.UI.Control.LoadRecursive() 
at System.Web.UI.Control.LoadRecursive() 
at System.Web.UI.Control.LoadRecursive() 
at System.Web.UI.Control.LoadRecursive() 
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) 

Error TargetSite: Traverse

        Overridable Public Function Fill(maxNumberOfItemsToReturn As Long, sortClauses As ISortExpression, allowDuplicates As Boolean, selectFilter As IPredicate, transactionToUse As ITransaction, groupByClause As IGroupByCollection, pageNumber As Integer, pageSize As Integer) As Boolean Implements ITypedView.Fill
            Dim fieldsInResultset As IEntityFields = GetFields()
            
            ' __LLBLGENPRO_USER_CODE_REGION_START AdditionalFields
            ' be sure To Call fieldsInResultset.Expand(number of New fields) first. 
            ' __LLBLGENPRO_USER_CODE_REGION_END
            
            Return DAOFactory.CreateTypedListDAO().GetMultiAsDataTable(fieldsInResultset, Me, maxNumberOfItemsToReturn, sortClauses, selectFilter, Nothing, allowDuplicates, groupByClause, transactionToUse, pageNumber, pageSize)
        End Function

llblgen version? Did you try the latest build and re-generate the code?

i am using LLBLGen v3.5 and i am using the latest build and have re-generated the code.

It seems that something is wrong with your predicate. Maybe you are including a field in the predicate that doesn't belong to the TypedView.

Please post the relevant code where you build the predicate and call the .Fill's typedView method. It should be on DSC.STARS.WEB.SDSearchInd.GetReferralData or DSC.STARS.BAL.Referral.SearchReferral.

This is the function where i am building the predicate:

Private Function GetSDDataBefore()

        Dim dtType As DataTable
        Dim udtTypeFilter As PredicateExpression = New PredicateExpression
        If StrComp(ViewMode.ToLower, "followup") = 0 Then
            'FOLLOWUP Session - StaffAssignmentId, CustomerReferralId and GroupSessionId values must all be present
            GetFollowupSessionDetails()
            udtTypeFilter.Add(ServiceDeliveryTypeDetailsFields.StaffAssignmentId = StaffAssignmentID)
            udtTypeFilter.Add(ServiceDeliveryTypeDetailsFields.CustomerReferralId = CustomerReferralID)
            udtTypeFilter.Add(ServiceDeliveryTypeDetailsFields.GroupSessionId = GroupSessionID)
        ElseIf StrComp(ViewMode.ToLower, "") = 0 Then
            'INDIVIDUAL DELIVERY - StaffAssignmentId and CustomerReferralId values must be present, GroupSessionId must be NULL
            udtTypeFilter.Add(ServiceDeliveryTypeDetailsFields.StaffAssignmentId = StaffAssignmentID)
            udtTypeFilter.Add(ServiceDeliveryTypeDetailsFields.CustomerReferralId = CustomerReferralID)
            udtTypeFilter.Add(ServiceDeliveryTypeDetailsFields.GroupSessionId = Nothing)
        ElseIf StrComp(ViewMode.ToLower, "customer") = 0 Then
            'GROUP DELIVERY (Staff Hours) - CustomerReferralId and GroupSessionId values must be present, StaffAssignmentId must be NULL
            udtTypeFilter.Add(ServiceDeliveryTypeDetailsFields.CustomerReferralId = CustomerReferralID)
            udtTypeFilter.Add(ServiceDeliveryTypeDetailsFields.GroupSessionId = GroupSessionID)
            udtTypeFilter.Add(ServiceDeliveryTypeDetailsFields.StaffAssignmentId = Nothing)
        Else
            'GROUP DELIVERY (Staff Hours) - StaffAssignmentId and GroupSessionId values must be present, CustomerReferralId must be NULL
            If StaffAssignmentID = Nothing Then
                StaffAssignmentID = LastStaffAssignmentID
            End If

            udtTypeFilter.Add(ServiceDeliveryTypeDetailsFields.StaffAssignmentId = StaffAssignmentID)
            udtTypeFilter.Add(ServiceDeliveryTypeDetailsFields.GroupSessionId = GroupSessionID)
            udtTypeFilter.Add(ServiceDeliveryTypeDetailsFields.CustomerReferralId = Nothing)
        End If
        udtTypeFilter.Add(ServiceDeliveryTypeDetailsFields.SeqNo >= ShownActivity_SeqNo)

        Dim udtTypeSort As SD.LLBLGen.Pro.ORMSupportClasses.SortExpression = New SD.LLBLGen.Pro.ORMSupportClasses.SortExpression
        udtTypeSort.Add(New SortClause(ServiceDeliveryTypeDetailsFields.SeqNo, SortOperator.Descending))

        'Create the Typed View object that will be used to return records from the database.

        dtType = BAL.ServiceDeliveryTypeDetail.Search(udtTypeFilter, udtTypeSort)
        If Not dtType Is Nothing AndAlso _
           dtType.Rows.Count > 0 Then
            dgTypesBefore.Visible = True
        Else
            dgTypesBefore.Visible = False

        End If

        Return dtType


    End Function

This is the funcation where it's calling the ServiceDeliveryTypedDetails View

Public Shared Function Search(ByVal Filter As PredicateExpression, _
                                           Optional ByVal Sort As SortExpression = Nothing, _
                                   Optional ByVal Transaction As Transaction = Nothing) As DataTable

        'Create a filter that will be used to return the relevant records
        'from the database.
        Dim udtFilter As PredicateExpression = New PredicateExpression
        If Not Filter Is Nothing Then
            udtFilter = Filter
        End If

        If Sort Is Nothing Then
            Sort = New SortExpression
            Sort.Add(New SortClause(ServiceDeliveryTypeDetailsFields.CustomerReferralId, SortOperator.Ascending))
        End If

        'Execute the search and return the results.
        Dim udtServiceDeliveryTypeDetails As New DAL.TypedViewClasses.ServiceDeliveryTypeDetailsTypedView
        If Transaction Is Nothing Then
            udtServiceDeliveryTypeDetails.Fill(0, Sort, True, Filter)
        Else
            udtServiceDeliveryTypeDetails.Fill(0, Sort, True, Filter, Transaction)
        End If
        Return udtServiceDeliveryTypeDetails

    End Function

I wonder why those methods don't show up in your stack trace (GetSDDataBefore, Search). Please post the code for the following methods:

• **DSC.STARS.WEB.SDSearchInd.GetReferralData() ** (in C:\TFSSourceCode\DSC.STARS\Main\DSC.STARS.WEB\SDSearchInd.aspx.vb:line 153)
• **DSC.STARS.BAL.Referral.SearchReferral(PredicateExpression Filter, SortExpression Sort, Transaction Transaction) ** (in C:\TFSSourceCode\DSC.STARS\Main\DSC.STARS.BAL\Referral.vb:line 385)

    Public Shared Function SearchReferral(ByVal Filter As PredicateExpression, _
                                           ByVal Sort As SortExpression, _
                                   Optional ByVal Transaction As Transaction = Nothing) As DataTable

        'Create a filter that will be used to return the relevant Referral records
        'from the database.
        Dim udtFilter As PredicateExpression = New PredicateExpression
        If Not Filter Is Nothing Then
            udtFilter = Filter
        End If

        'Execute the search and return the results.
        Dim udtReferral As New DAL.TypedViewClasses.SdsearchTypedView

        If Transaction Is Nothing Then
            udtReferral.Fill(0, Sort, True, Filter)
        Else
            udtReferral.Fill(0, Sort, True, Filter, Transaction)
        End If

        Return udtReferral

    End Function

Private Function GetReferralData()

        DAL.DaoClasses.CommonDaoBase.CommandTimeOut = Common.GetWebConfigSetting(WEB_CONFIG_COMMAND_TIMEOUT)

        Dim dtReferral As DataTable
        Dim udtReferralFilter As PredicateExpression = New PredicateExpression
        udtReferralFilter.Add((SdsearchFields.DirectorateName = GetUserRoleDirectorate()) And (SdsearchFields.EmployeeNumber = CurrentUserEmployeeNumber()) And (SdsearchFields.GroupName = Nothing))

        If ddlStatus.SelectedValue <> NO_FILTER Then
            udtReferralFilter.Add(SdsearchFields.ReferralStatusId = ddlStatus.SelectedValue)
        End If
        If ddlCustomer.SelectedValue <> NO_FILTER Then
            udtReferralFilter.Add(SdsearchFields.CustomerId = ddlCustomer.SelectedValue)
        End If
        If ddlTeam.SelectedValue <> NO_FILTER Then
            udtReferralFilter.Add(SdsearchFields.TeamId = ddlTeam.SelectedValue)
        End If

        Dim udtReferralSort As SD.LLBLGen.Pro.ORMSupportClasses.SortExpression = New SD.LLBLGen.Pro.ORMSupportClasses.SortExpression
        udtReferralSort.Add(New SortClause(SdsearchFields.CustomerName, SortOperator.Ascending))

        'Create the Typed View object that will be used to return records from the database.

        dtReferral = BAL.Referral.SearchReferral(udtReferralFilter, udtReferralSort)
        If Not dtReferral Is Nothing AndAlso _
           dtReferral.Rows.Count > 0 Then
            dgReferrals.Visible = True
            lblReferralsMessage.Text = "A total of " & dtReferral.Rows.Count & " Referral(s) found."
            lblReferralsMessage.Visible = True
        Else
            dgReferrals.Visible = False
            lblReferralsMessage.Text = "No Referrals found."
            lblReferralsMessage.Visible = True
        End If

        Return dtReferral

    End Function

Could you please create and send a repro solution, with the llblgen project file?

The first pieces of code you gave have nothing to do with the problem. The last pieces of code you gave show the real methods you called, however there's 1 missing: GetUserRoleDirectorate()

the problem is that the crash happens in a visitor which visits the predicate and it finds an expression. However in your code there's no expression specified, so it can only be done in GetUserRoleDirectorate(): either it returns a field, or it returns a field with an expression.

Looking at our code, it seems the expression constructed has a null value for the field used in the expression. (so field == null). Please check GetUserRoleDirectorate() to see whether it can return null or that it constructs an expression which contains null for a field.

Btw, you don't have to check whether transaction is null for calling Fill(), the Fill() method will do that for you.

Hello vivek,

i had the same issue! Try to replace your 'NOTHING'-Statements in the predicates with System.DBNull.Value. That did it for me. Previously, i used 'NOTHING' too, in my predicates without any problem. But suddenly i got the Exception. No idea why the same predicate worked before... (BTW. using MS-SQL 2008 R2).

RitterSport wrote:

i had the same issue! Try to replace your 'NOTHING'-Statements in the predicates with System.DBNull.Value. That did it for me. Previously, i used 'NOTHING' too, in my predicates without any problem. But suddenly i got the Exception. No idea why the same predicate worked before... (BTW. using MS-SQL 2008 R2).

Thanks for the feedback. Actually yes, that is the correct way to filter null according to the documentation.