Entity Framework 4 - Navigation Property Object Null on Client Side - entity-framework

Question

There are two tables of interest in my entity conceptual model: tblProducts and tblInstalledProducts.
Each installed product has a ProductID foreign key linking it to a specific product, which was set up automatically as a navigation property.
Within the entity domain service I have the following query:
public IQueryable<tblInstalledProduct> GetInstalledProductsBySiteID(string SiteID)
{
ObjectSet<tblInstalledProduct> installedProducts = this.ObjectContext.tblInstalledProducts;
var filterBySite =
from p in installedProducts.Include("tblProduct")
where p.SiteID == SiteID
select p;
return filterBySite;
}
I have a DataGridView bound to a DomainDataSource configured to use this query.
When I debug this query, p.tblProduct and p.tblProductReference are populated as expected. The problem arises when trying to access the tblProduct property of any tblInstalledProduct from the client side.
//Find associated install record for the selected product
tblInstalledProduct selectedInstall =
Context.tblInstalledProducts.Where(
p => p.SiteID == "Site1" && p.ProductID == 38
).First();
string productName = selectedInstall.tblProduct.ProductName;
For some reason tblProduct is always null. I've tried .Include() / .Load() and can't seem to get it to populate itself.
Why is tblInstalledProduct.tblProduct loaded up as expected on the service side of things, but is seemingly inaccessible on the client side?
Thanks for reading.
Edit:
XAML DataSource:
<telerik:RadDomainDataSource x:Key="InstalledProductsDataSource"
Name="InstalledProductsDataSource"
DomainContext="{StaticResource DomainContext}"
AutoLoad="True"
QueryName="GetInstalledProductsInfoBySiteID"
SubmittedChanges="InstalledProductsDataSource_SubmittedChanges">
<telerik:RadDomainDataSource.QueryParameters>
<telerik:QueryParameter
ParameterName="SiteID"
Value="{Binding SelectedValue,ElementName=SiteList}" />
</telerik:RadDomainDataSource.QueryParameters>
</telerik:RadDomainDataSource>
XAML DataGrid:
<telerik:RadGridView x:Name="InstalledProductsGridView"
ItemsSource="{Binding DataView, Source={StaticResource InstalledProductsDataSource}}">
<telerik:RadGridView.Columns>
<telerik:GridViewDataColumn Header="Product Name" DataMemberBinding="{Binding ProductName, Mode=TwoWay}" />
<telerik:GridViewDataColumn Header="Version" DataMemberBinding="{Binding ProductVersion, Mode=TwoWay}" />
<telerik:GridViewDataColumn Header="Description" DataMemberBinding="{Binding Description, Mode=TwoWay}" />
</telerik:RadGridView.Columns>
</telerik:RadGridView>
Right now the grid is bound to a collection of tblProducts, but I'd like to bind it to a collection of tblInstalledProducts (as there is some extra information in that table that I need access to) like so:
<telerik:RadGridView.Columns>
<telerik:GridViewDataColumn Header="DateInstalled" DataMemberBinding="{Binding DateInstalled, Mode=TwoWay}" />
<telerik:GridViewDataColumn Header="Product Name" DataMemberBinding="{Binding tblProduct.ProductName, Mode=TwoWay}" />
<telerik:GridViewDataColumn Header="Version" DataMemberBinding="{Binding tblProduct.ProductVersion, Mode=TwoWay}" />
<telerik:GridViewDataColumn Header="Description" DataMemberBinding="{Binding tblProduct.Description, Mode=TwoWay}" />
</telerik:RadGridView.Columns>

Answer 1

you need to do something like this
tblInstalledProduct selectedInstall = Context.GetInstalledProductsBySiteID("Site1").Where(p=> p.ProductID == 38 ).FirstOrDefault();
string productName="";
if(selectedInstall !=null)
{
productName= selectedInstall.tblProduct.ProductName;
}
for testing try to use;
public IQueryable<tblInstalledProduct> GetInstalledProductsNew()
{
//Im nut Sure of 'tblProduct' or 'tblProducts' it is dependent on your relations
return this.ObjectContext.tblInstalledProducts.Include("tblProduct");
}

Answer 2

For anyone else having problems with this, I did eventually find the solution. You need to use both .Include() on the query to tell it to load related objects, as well as the [Include] attribute in the metadata to allow those related objects to be serialized and sent to the client.