Md. Adil Akhter's Weblogs

Passing Parameter to a Predicate in .Net2.0

In this post, we will see how to pass parameter to a method representing Predicate.

Let's say, we have a collection of SprintBacklogItem and we want to filter all the SprintBacklogItem with Title start's with, let say "QA" or "Dev Task" depending on a input parameter. Now from the previous post we know that , predicate only have 1 parameter of type T.

Then, how to pass a input parameter _HeaderToSearch in Predicate?

1. To do that, we need to a new object called ListMatcher -

public class ListMatcher 
   { 
       private string _HeaderToSearch; 
       public ListMatcher(string headerToSearch) 
       { 
           _HeaderToSearch = headerToSearch; 
       }  

       public bool Predicate(SprintBacklogItem item) 
       { 
           return item.Title.StartsWith(_HeaderToSearch, StringComparison.InvariantCultureIgnoreCase); 
       }  

   }  

2. Next , I initialized the ListMatcher object and use the HeaderToSearch  to filter the items-

ListMatcher matcher = new ListMatcher("QA"); 
this.FindAll(matcher.Predicate);

Done.:)