IQueryable (non generic) : missing Count and Skip ? it works with IQueryable

Question

i have an extension method which a person was really helpful to give me... it does an orderby on IQueryable ... but i wanted one to do a normal IQueryable (non generic)

Answer 1

Well, quite simply those methods aren't available for IQueryable. If you look at the Queryable methods you'll see they're almost all based on IQueryable<T>.

If your data source will really be an IQueryable<T> at execution time, and you just don't know what T is, then you could find that out with reflection... or in C# 4, just use dynamic typing:

public static IQueryable GetPage(this IQueryable query,
     int page, int pageSize, out int count)
{
    int skip = (int)((page - 1) * pageSize);
    dynamic dynamicQuery = query;
    count = Queryable.Count(dynamicQuery);
    return Queryable.Take(Queryable.Skip(dynamicQuery, skip), pageSize);
}

The dynamic bit of the C# compiler will take care of working out T for you at execution time.

In general though, I'd encourage you to just try to use the generic form everywhere instead - it's likely to be significantly simpler.

Answer 2

The question is old but when someone needs the IQueryable extension methods then he/she should return IQueriable when the return type is anonymous.