How to get lookup value only via REST (listdata.svc)

Question

I am trying to retrieve a list of items including lookup fields via listdata.svc. My lookup points to a list of companies which has the following fields: Title, Address, Phone.

By default, listdata doesn't return the lookup data, only a link to it. If I use the $expand parameter, then listdata returns all the fields of the lookup.

How can I make listdata return the lookup Title only, not the other fields like Address and Phone?

Answer 1

This page has some good examples on using listdata.svc and specific examples on drilling down into specific items to be selected.

Using the REST Interface

Examples from page

Using code:

var query = (DataServiceQuery<InventoryLocationsItem>)context.
    CreateQuery<InventoryLocationsItem>("InventoryLocations")
       .Expand("Part")
       .AddQueryOption("$select", 
                       "BinNumber,Quantity,Title,Id,PartId,Part/SKU,Part/Title")
       .Where(p => p.Part.SKU.StartsWith(SearchSku)).OrderBy(p => p.Part.SKU);

Manually constructing the URL:

http://contoso/sites/sharepointlist/_vti_bin/listdata.svc/InventoryLocations()
  ?$filter=startswith(Part/SKU,'sku')
    &$orderby=Part/SKU
      &$expand=Part
        &$select=BinNumber,Quantity,Title,Id,PartId,Part/SKU,Part/Title

Answer 2

Assuming that the Title is the "foreign key" don't you already have that value in the primary list? Alternatively, don't you get the values if you add the other columns to the Lookup column to pull them across with the key?