removing duplicates in a list with linq

Question

Suppose you have a list of MyObject like this:

public class MyObject
{
  public int ObjectID {get;set;}
  public string Prop1 {get;set;}
}

Answer 1

You can do this using the Distinct() method. But since that method uses the default equality comparer, your class needs to implement IEquatable like this:

public class MyObject : IEquatable
{
    public int ObjectID {get;set;}
    public string Prop1 {get;set;}

    public bool Equals(MyObject other)
    {
        if (other == null) return false;
        else return this.ObjectID.Equals(other.ObjectID); 
    }

    public override int GetHashCode()
    {
        return this.ObjectID.GetHashCode();
    }
}

Now you can use the Distinct() method:

List myList = new List();
myList.Add(new MyObject { ObjectID = 1, Prop1 = "Something" });
myList.Add(new MyObject { ObjectID = 2, Prop1 = "Another thing" });
myList.Add(new MyObject { ObjectID = 3, Prop1 = "Yet another thing" });
myList.Add(new MyObject { ObjectID = 1, Prop1 = "Something" });

var duplicatesRemoved = myList.Distinct().ToList();