Question

Here’s a wild one. I’m writing a universal entity editor using JQuery and NHibernate LINQ. So far everything works great. But now I’m trying to add sorting support. Things have gotten tricky. I want to tell it to sort on a property, but in the class, I will not know what kind of object it is until runtime.

Here’s the code:

data =
    (from entity in _repository.FindAll()
    orderby entity.GetType().GetProperty(formData["sidx"]).GetValue(entity, null)
    select entity).ToList();

Here’s the problem, I get a null pointer exception when I do this. Any clues on how I can do what I want to do? I suspect this issue is going to come up again when I do searching.

Answer 1

Use Dynamic LINQ (http://weblogs.asp.net/scottgu/archive/2008/01/07/dynamic-linq-part-1-using-the-linq-dynamic-query-library.aspx, section Downloading the LINQ Dynamic Query Library) and specify the field to sort by as a string:

data = _repository.FindAll().OrderBy(formData["sidx"].ToString()).ToList();