'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

From MSDN:

static Expression> BuildContainsExpression(
    Expression> valueSelector, IEnumerable values)
{
    if (null == valueSelector) { throw new ArgumentNullException("valueSelector"); }
    if (null == values) { throw new ArgumentNullException("values"); }
    ParameterExpression p = valueSelector.Parameters.Single();

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

    var equals = values.Select(
             value => (Expression)Expression.Equal(valueSelector.Body, Expression.Constant(value, typeof(TValue))));

    var body = equals.Aggregate((accumulate, equal) => Expression.Or(accumulate, equal));

    return Expression.Lambda>(body, p);
} 

and the query becomes:

var query2 = context.Entities.Where(BuildContainsExpression(e => e.ID, ids));