Custom TYPE_MAPPING

[marshmallow-code]

Custom TYPE_MAPPING

[fuhrysteve]

Hmm, not sure if I am misunderstanding your issue or not, but you could also do something like this if you wanted something resembling a custom TYPE_MAPPING in your BaseSchema:

class BaseSchema(ModelSchema):
    class Meta:
        model_converter = MyDefaultConverter
        # other defaults

class MyModelSchema(BaseSchema):
    class Meta(BaseSchema.Meta):
        # MyModelSchema specific customizations
        pass

The only downside is that you need to remember to have your Meta classes extend BaseSchema.Meta if you want to customize it further.

[fuhrysteve]

@dwieeb You're pretty close. I think you're looking for something like this:

from marshmallow_sqlalchemy import ModelSchema, ModelConverter
from sqlalchemy_utils.types import TimezoneType
from marshmallow import fields

class SQLAlchemyUtilsConverter(ModelConverter):
    SQLA_TYPE_MAPPING = dict(
        list(ModelConverter.SQLA_TYPE_MAPPING.items()) +
        [(TimezoneType, fields.Str)]
    )

class MyModelSchema(ModelSchema):
    class Meta:
        model_converter = SQLAlchemyUtilsConverter

only in your case, something more like:

class MyConverter(ModelConverter):
    SQLA_TYPE_MAPPING = dict(
        list(ModelConverter.SQLA_TYPE_MAPPING.items()) +
        [(datetime, APIDateTime)]
    )

[imhoffd]

Yeah, I know I can override ModelConverter, I just don't want to. Code bases can easily use thousands of schemas. I shouldn't have to specify model_converter = for each one when I have a BaseSchema with a TYPE_MAPPING that should be picked up.

I think marshmallow-sqlalchemy needs a patch such that _get_field_class_for_data_type() is called with a reference to model from fields_for_model() so that it can use the TYPE_MAPPING from the user's schema classes OR fall back to marshmallow.Schema's TYPE_MAPPING.

[imhoffd]

Yeah, that'd be fine for my use case.

I still think the built-in ModelConverter should respect the schema class's type mapping, and not be hardcoded to use the marshmallow schema's type mapping--that's not how inheritance should work. 😕

Perhaps I will do a PR to see how the change is received.

[fuhrysteve]

Yeah, I'm not sure if that's intentional or not. PR would be a great way to find out haha

[sloria]

#49 should address this issue. ModelSchema will now respect a Schema subclass's TYPE_MAPPING.

[imhoffd]

Awesome, @sloria! Thank you.