Table Controller With 1:N Relationship

Question

I'm looking at implementing a table controller with a 1:N relationship as per the following blog post: http://blogs.msdn.com/b/azuremobile/archive/2014/06/18/insert-update-related-data-with-1-n-relationship-using-net-backend-azure-mobile-services.aspx
However, when I run the sample solution given, an exception is thrown when I call the following controller method:
public SingleResult<TodoItemDTO> GetTodoItem(string id)
return Lookup(id);
The exception thrown: 
The LINQ expression node type 'Invoke' is not supported in LINQ to Entities.
The sample solution can be found here: https://github.com/pragnagopa/BlogSamples/tree/master/InsertUpdateRelatedData
Can anyone explain why this is not working?

Answer 1

Hi,
As per you requirement, it seems like a Field in main table is look up to Flat table which contains Two fields say Field A and Field B both as display fields. Field A has two values 100 and 200 only and Field B has six values P, Q, R, X, Y, Z.
You want whenever you select Field A as 100 then only P, Q, R comes.
I firmly believe that this is not achievable as per MDM capability using Fields. But you can run Validations to cross check that if it is 100 then correspondingly value of Field B should be from P, Q and R only. IIy, for 200 it should be from X, Y and Z.
Alternatively, I can suggest you to go for Taxonomy. Create 2 categories say category name Field100 and Field200.
Field100 category is linked with attribute 100 which has values P, Q and R.
Field200 category is linked with attribute 200 which has values X, Y and Z.
So whenever you select category Field100 associated linked attribute 100 will come and whose values can be populated using P, Q and R only.
lly, when you select category Field200 associated linked attribute 200 will come and can be populated using X,Y and Z only. Whenever for a record in main table you select this category field as Field100 and Field200 correspondingly linked Attribute comes with Predefined set of legal values.
Thanks and Regards,
Mandeep Saini