OData $filter with items in a $expand

Question

I have given some web services to access informations.

The first thing that i have tries to expand a node . And i have done that successfully with following code

Answer 1

Filtering by child object's properties is supported in oData.

Here is an example: http://services.odata.org/Northwind/Northwind.svc/Orders?$filter=Customer/Country eq 'Germany'