Question

I know I shouldn’t have id’s with the same value. This is just fictitious, so overlook that.

I have:

List<Car> carList = new List<Car>();
carList.Add(new Car() { id = 1, name = "Honda" });
carList.Add(new Car() { id = 2, name = "Toyota" });
carList.Add(new Car() { id = 1, name = "Nissan" });

I want to use Lambda Expression to retrieve all cars that have an id of 1.

Anticipated Result:

-- Id: 1, Name: Honda
-- Id: 1, Name: Nissan

The problem is more filtering an object list based on a foreign key.

Answer 1

Use LINQ:

IEnumerable<Car> matchingCars = carList.Where(car => car.id == 1);

Using List<T>.FindAll:

List<Car> matchingCars = carList.FindAll(car => car.id == 1);

I would prefer the LINQ approach personally – note that that is lazy, whereas FindAll immediately looks through the whole list and builds a new list with the results.