How do I deserialize an object using BinaryFormatter that contains a field that no longer exists?

Question

Say I created a data class some time ago:

[Serializable]
public class MyData
{
  public string name;
  public string nickname;
  public int id;
}

And I used BinaryFormatter to serialize and save users' data to a file. After time has passed, I decide we no longer need the field "nickname," so I remove it:

[Serializable]
public class MyData
{
  public string name;
  public int id;
}

However, now when I try to deserialize an object that was serialized when it still contained the nickname field, it throws an exception:

System.Runtime.Serialization.SerializationException: Field "nickname" not found in class MyData

Is there a way to tell the BinaryFormatter that if it encounters the field nickname to just ignore it and deserialize the rest of the fields as normal?

Answer 1

No, this is impossible. What you have to do is deserialize it to a class with the same structure as before, then manually migrate your old object to your new object, and save the new object for the future.