Dynamic Expression using LINQ. How To Find the Kitchens?

Question

I try do implement a user dynamic filter, where used selects some properties, selects some operators and selects also the values.

As I didn\'t find yet an answer to

Answer 1

I wouldn't build the where clause in that way - I think it's more complex than it needs to be for your needs. Instead, you can combine where clauses like this:

var houses = new List(new House[] { myHouse, yourHouse, donaldsHouse });

// A basic predicate which always returns true:
Func housePredicate = h => 1 == 1;

// A room name which you got from user input:
string userEnteredName = "a Room";

// Add the room name predicate if appropriate:
if (!string.IsNullOrWhiteSpace(userEnteredName))
{
    housePredicate += h => h.MainRoom.Name == userEnteredName;
}

// A room type which you got from user input:
RoomType? userSelectedRoomType = RoomType.Kitchen;

// Add the room type predicate if appropriate:
if (userSelectedRoomType.HasValue)
{
    housePredicate += h => h.MainRoom.Type == userSelectedRoomType.Value;
}

// MainRoom.Name = \"a Room\" and Rooms.Count = 3 or 
// ?????????????????????????
var aRoomsHouses = houses.AsQueryable().Where(housePredicate);

I tested this one, honest :)