Metadata: Check on typing for client mode #6490

[voetberg]

No description provided.

[bari12]

Merging it like this; I am just wondering in general if we should do it like this or park these types in an actual (client accessible) type module and not hide it behind if TYPE_CHECKING.

[dchristidis]

Upon closer inspection, the use of KeyType (and anything in constants.py) was wrong. Instances of Enum are not JSON-serialisable, so they can’t be used. The correct hint would have been Literal['ALL', 'COLLECTION', …].

So we don’t have to consider how to import them because we shouldn’t in the first place.

[bari12]

Let's change this again then in a following minor release.
Though adding the Literals there also seems error-prone, since we would have to manually keep them in sync with the Enums (In case we keep them and do not change these as well). But my feeling is that we need to have stricter rules there between types used on the client side, types used in the core and types used in the database layer.