Feature - allow inheriting load_default from nested schema populated with from_dict

[nneul]

Using with APIFlask

class APICreateTicketIn(Schema):
    notify = fields.Nested(
        Schema.from_dict(
            {
                "reviewer": fields.Boolean(load_default=False),
                "requestor": fields.Boolean(load_default=False),
                "responsible": fields.Boolean(load_default=False),
            },
            name="APICreateTicketIn_Notify",
        ),
        load_default={
            "reviewer": False,
            "requestor": False,
            "responsible": False,
        },
        required=False,
    )

If only the 'load_default' in the nested "notify" schema are supplied, it doesn't actually get any defaults - had to add the raw load_default in the top level schema object. (I think the load_default in the from_dict isn't used at all.)

[nneul]

Note - if I partially specify notify - i.e. just notify["reviewer"] - the load_default from the other individual fields is used. So maybe this is actually operating "as expected".

[lafrech]

I think the fact that the schema is generated with from_dict is irrelevant. It behaves the same when declaring the schema with the usual constructor.

class Notify(Schema):
    reviewer = fields.Boolean(load_default=False)
    requestor = fields.Boolean(load_default=False)
    responsible = fields.Boolean(load_default=False)

Also, from my tests, the load_default in the Nested constructor call has no impact, only the values in from_dict (or the equivalent class declaration) work.