SerializeField default value only updates after reimporting prefab

Unity Engine
, ,
1

I’m using unity 2021 LTS.

I understand the following situation is intended.

  1. Create a Monobehaviour script, TestScript.cs
  2. Add a SerializeField variable, [SerializeField] private int testValue = 10;
  3. Attach the script to a prefab, TestPrefab.prefab
  4. Change the default value of testValue to 20
  5. testValue of TestPrefab remains at 10 (in TestPrefab.prefab file, there is ‘testValue: 10’)

But I cannot understand the following situation.

  1. Create a Monobehaviour script, TestScript.cs
  2. Attach the script to a prefab, TestPrefab.prefab
  3. Add a SerializeField variable, [SerializeField] private int testValue = 10;
  4. Change the default value of testValue to 20
  5. Double-click TestPrefab, testValue of TestPrefab changed to 20
  6. Add TestPrefab to scene, testValue of TestPrefab remains at 10 (in TestPrefab.prefab file, there is no ‘testValue’)
  7. Reimport TestPrefab
  8. Add TestPrefab to scene, testValue of TestPrefab changed to 20

Is this intended behavior?
Is the only way to update all default values to reimport all assets?

2

Probably because the initial inline initialised value gets cached in some way upon the prefab being reserialised for the first time. Even if it’s not written to disk yet as the prefab hasn’t been dirtied and saved yet. The serialiser sees a value that wasn’t present before, and adds the initial value to the in memory instance of the prefab.

A reimport probably clears this caching, though I bet simply closing and opening the editor would get the same effect.

If the field hasn’t even been written to disk then you can just dirty the prefab somehow to ensure it is.

3

Restarting the editor didn’t fix the issue.
Because Unity does not reimport assets when restarted.

And I found the same issue occurs on the public variable too.

4

There is functionally no difference between public fields and fields decorated with SerializeField.

And again if the value is not written to disk yet, just ensure it is.