DataFormComboBoxField: ForeignKeyReferenceAlreadyHasValueException

[Gerrit]

Hello,

we currently have the following problem:

There is a table named ST_Classification and one named ST_Address, which have the following relationship:
ST_classification.PK_classification -> ST_Address.FK_classification

In a WPF-Application there is a DataFormComboBoxField which is populated with data from the ST_Classification table.
The moment the value is set to a new one an exception is thrown:
System.Data.Linq.ForeignKeyReferenceAlreadyHasValueException was unhandled by user code
Message=Operation is not valid due to the current state of the object.

This is code in the xxx.designer.cs where the exception is thrown:

[global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_FK_classification", DbType="BigInt", UpdateCheck=UpdateCheck.Never)]
        public System.Nullable<long> FK_classification
        {
            get
            {
                return this._FK_classification;
            }
            set
            {
                if ((this._FK_classification != value))
                {
                    if (this._ST_classification.HasLoadedOrAssignedValue)
                    {
                        throw new System.Data.Linq.ForeignKeyReferenceAlreadyHasValueException();
                    }
                    this.OnFK_classificationChanging(value);
                    this.SendPropertyChanging(); // <--- Exception is thrown!
                    this._FK_classification = value;
                    this.SendPropertyChanged("FK_classification");
                    this.OnFK_classificationChanged();
                }
            }
        }

This is the XAML-code for the DataFormComboBoxField:

<telerik:RadDataForm x:Name="RDF_ST_Addresse" ItemsSource="{Binding Items, ElementName=RG_ST_Partner}"
 AutoGenerateFields="False"
 EditEnding="RDF_ST_Addresse_EditEnding"
EditEnded="RDF_ST_Addresse_EditEnded"
DeletingItem="RDF_ST_Addresse_DeletingItem"
ValidatingItem="RDF_ST_Addresse_ValidatingItem"
AddingNewItem="RDF_ST_Addresse_AddingNewItem"
AddedNewItem="RDF_ST_Addresse_AddedNewItem" >
.
.
.
<telerik:DataFormComboBoxField DataMemberBinding="{Binding FK_classification, Mode=TwoWay}"  Name="DFCMB_classification"
Label="Klassifikation" IsReadOnly="False"
SelectedValuePath="PK_classification"
DisplayMemberPath="classification" Initialized="DFCMB_classification_Initialized" />

Here is the codeBehind for DataFormComboBoxField:

private void DFCMB_classification_Initialized(object sender, EventArgs e)
            {
                ((DataFormComboBoxField)sender).ItemsSource = from p in goDCAddach.ST_classifications orderby p.classification     select p ;
            }

 Thanks for any help in advance.

Greetings
Gerrit

[Ivan Ivanov]

Hello Gerrit,

Would it be possible for you to send us a simple repro project via a support ticket, so that we could debug it on our side?

Kind regards,
Ivan Ivanov
the Telerik team