How to use predicate builder to return active users who satisfy certain search condition?

Question

I am using Predicate Builder to build a dynamic EF predicate.

I want to return all Active users whose firstname or lastname matches the requested search term. Here is what I have tried but but I always get all of the active users... it means the search is not narrowed down by the search term:

string searchTerm = "John"; // <-- comes from user
predicate = predicate.And(u => u.IsActive == true);

if (!string.IsNullOrEmpty(searchTerm))
{
    predicate = predicate.Or(u => u.FirstName.Contains(searchTerm));
    predicate = predicate.Or(u => u.LastName.Contains(searchTerm));
}

Answer 1

Break down your logic into a simple boolean expression -

x = IsActive == true
y = FirstName match
z = LastName match

Your logic is x or y or z. If the user is active, they will get returned.

You are wanting x and (y or z). Inside your if statement, something like -

predicate = predicate.And(u => u.FirstName.Contains(searchTerm) || u.LastName.Contains(searchTerm));