Querying Entity with LINQ using Dyanmic Field Name

Question

I have created a dynamic search screen in ASP.NET MVC. I retrieved the field names from the entity through reflection so that I could allow the user to choose which fields

Answer 1

After a lot more trial and error and searching I accidentally found another SO post that covers the same issue:

InvalidOperationException: No method 'Where' on type 'System.Linq.Queryable' is compatible with the supplied arguments

Here is my modified code that works:

        IQueryable query = entities.People;
        Type[] exprArgTypes = { query.ElementType };

        string propToWhere = "FirstName";            

        ParameterExpression p = Expression.Parameter(typeof(People), "p");
        MemberExpression member = Expression.PropertyOrField(p, propToWhere);
        LambdaExpression lambda = Expression.Lambda>(Expression.Equal(member, Expression.Constant("Scott")), p);                            

        MethodCallExpression methodCall = Expression.Call(typeof(Queryable), "Where", exprArgTypes, query.Expression, lambda);

        IQueryable q = query.Provider.CreateQuery(methodCall);

With some hopefully pretty easy modifications, I should be able to get this to work with any type.

Thanks again for your answers Ani & John Bowen