Question

I tried to call linq query from sliverlight application to web service which is ‘ADD.NET Entity Data Model’ with ‘WCF Data Service’. The linq below is working (e.g.using pre-defined table & field names):

        var query = from o in context.ORDER
                    where o.NUMBER == 1
                    select o;

        ((DataServiceQuery<ORDER>)query).BeginExecute(OnQueryComplete, query);    

But I need dynamically assign different table and fields names to the linq query. Is there any way? Do I need to write a method in WCF to execute any sql command?

Thanks for any help.

Answer 1

You can use the Dynamic Linq samples to provide dynamic field names in where clauses – see: http://weblogs.asp.net/scottgu/archive/2008/01/07/dynamic-linq-part-1-using-the-linq-dynamic-query-library.aspx

Further, you can do this in a type-safe way using PredicateBuilder – http://www.albahari.com/nutshell/predicatebuilder.aspx

For more dynamic behavior – including dynamic table names – the only Linq option I can think of is to compile some code at runtime within your app using the CSharpCodeProvider (http://support.microsoft.com/kb/304655). However, obviously you need to be careful with security when offering this from a web service.