that would just overwrite the fields with the latest model. merge might mean addition of int fields, and things like that.

Anaddition of int fields is well supported by python built-in functionality (e.g.|), butdeep merging of the dicts is required for anything non-trivial; see@mccauleyp's code sample.

I think they meant literal addition of int values, e.g.{d: 5} + {d: 6} = {d: 11}; the point being that merge may have different semantics for different value types.

Oh,that kind of addition! OK, didn't think of that - I thought ofadding model fields with integer type.
Thanks for pointing that out.

Your code sample is not a merge, though; in fact, it's not even valid python - missing quotes for starters, but more importantly,+ is not supported for dicts:

>>> {d: 5} + {d: 6}Traceback (most recent call last):  File "<python-input-0>", line 1, in <module>    {d: 5} + {d: 6}     ^NameError: name 'd' is not defined. Did you mean: 'id'?>>> {'d': 5} + {'d': 6}Traceback (most recent call last):  File "<python-input-1>", line 1, in <module>    {'d': 5} + {'d': 6}    ~~~~~~~~~^~~~~~~~~~TypeError: unsupported operand type(s) for +: 'dict' and 'dict'

Also, why would anyone try to add numbers in model instance field value - and expect the result to be the sum ?
I can't seem to think of a use case - that does not involve mixing concerns.

Anyway, recipe for merging model instances: Turn them into dicts usingmodel_dump(...) and deepmerge those ✅

Your code sample is not a merge, though; in fact, it's not even valid python - missing quotes for starters, but more importantly, + is not supported for dicts:

I was presenting it to communicate the idea, not as a literal Python example.

Also, why would anyone try to add numbers in model instance field value - and expect the result to be the sum ?
I can't seem to think of a use case - that does not involve mixing concerns.

Here's some valid Python thatdoes behave exactly in this way, to motivate:

>>>fromcollectionsimportCounter>>>Counter({"a":5})+Counter({"a":6})Counter({'a':11})