dynamic sort in linq
c#, c#-4.0, expression-trees, lambda, linq
Solution
OrderBy does not do an in-place sort. It returns a sequence which when evaluated will be sorted. This is usually done lazily, meaning: until it is enumerated, it does nothing. Your current code simply discards this all-important return value. The fix is simple: catch the return value:
query = query.OrderBy("CustomerID", SortDirection.Ascending);
Note: similarly, applying "Where" doesn't filter the existing data: it returns a sequence that when enumerated is filtered. So if you were filtering you'd have the similar:
query = query.Where(...);
Problem
please consider this scenario: I have a list of a class with about 50 fields.I want to have a Combobox that user can select according to what field list will sort.For example if user select "F1" list sort according to "F1". I don't want to sort with `if-else` for every fields.I see this topic : Sorting a gridview when databinding a collection or list of objects but I can't use of it's answer. How I can use `Expression Tree` for this purpose? thanks Edit 1) : According to dear @Thom Smith answer I wrote this code: ``` using (NorthwindModel1.NorthwindEntities2 ent = new NorthwindModel1.NorthwindEntities2()) { var query = from o in ent.Orders where o.OrderID < 10257 select o; query.OrderBy("CustomerID", SortDirection.Ascending); GridView1.DataSource = query; GridView1.DataBind(); } ``` but it was not sorted. if I wrote that code in this way: ``` GridView1.DataSource = query.OrderBy(o=>o.CustomerID); ``` it being sort. where is the problem?