'Contains()' workaround using Linq to Entities?

Question

I\'m trying to create a query which uses a list of ids in the where clause, using the Silverlight ADO.Net Data Services client api (and therefore Linq To Entities). Does any

Answer 1

To complete the record, here's the code I finally used (error checking omitted for clarity)...

// How the function is called
var q = (from t in svc.OpenTransaction.Expand("Currency,LineItem")
         select t)
         .Where(BuildContainsExpression(tt => tt.OpenTransactionId, txnIds));



 // The function to build the contains expression
   static System.Linq.Expressions.Expression> BuildContainsExpression(
                System.Linq.Expressions.Expression> valueSelector, 
                IEnumerable values)
        {
            if (null == valueSelector) { throw new ArgumentNullException("valueSelector"); }
            if (null == values) { throw new ArgumentNullException("values"); }
            System.Linq.Expressions.ParameterExpression p = valueSelector.Parameters.Single();

            // p => valueSelector(p) == values[0] || valueSelector(p) == ...
            if (!values.Any())
            {
                return e => false;
            }

            var equals = values.Select(value => (System.Linq.Expressions.Expression)System.Linq.Expressions.Expression.Equal(valueSelector.Body, System.Linq.Expressions.Expression.Constant(value, typeof(TValue))));
            var body = equals.Aggregate((accumulate, equal) => System.Linq.Expressions.Expression.Or(accumulate, equal));
            return System.Linq.Expressions.Expression.Lambda>(body, p);
        }