Intercepting data before validation

[nicklasb]

I am trying to edit a part of the model directly, the JSON itself.
My problem is that this means that a part of the schema expects an object.
I have found no nice way of intercepting the data before it reaches validation, adding a $validator lets me check that it is valid JSON, is would be great if I there could also affect the actual data in some way and convert the text to the object the validator expects..
Preferably without having to write my own add-on..

[Anthropic]

@nicklasb any solution suggestions on this? Calculate add-on I added would cover this to a point I suspect.