The default value specified in the field when the value is None

[FRiMN]

I have scheme like this:

class NullProcessingSchema(Schema):
    @post_load
    def null_to_default_value(self, data: dict, **kwargs):
        return {
            key: (0 if key == 'field_1' and value is None else value)    # explicit field name
            for key, value in data.items()
        }

class ContentData(NullProcessingSchema):
    field_1 = fields.Int(allow_none=True)
    field_2 = fields.Str(allow_none=True)
    # etc...

I have many fields with different types in ContentData.
I don't want to explicitly list the field names in post_load.

Is there a way to define a default value (when None) in the field itself?
Or is it possible to get the type of a field in post_load?

[lafrech]

You can't do that at field level.

You can remove the key == "field_1" condition if all None values should be turned into 0. If the value depends on the field type, it won't work.

A better alternative would be to use a pre_load method to remove None values and use the missing parameter. Then you can remove allow_none=True.

[FRiMN]

The problem is that the fields are present alternatively: either field_1 or field_2, etc.

If you're interested, this is the Amazon Alexa API answer (xml):

<aws:ContentData>
      <aws:DataUrl type="canonical">example.com/</aws:DataUrl>
      <aws:LinksInCount/>    <!-- This field is defined in the API request and can be different -->
</aws:ContentData>

[lafrech]

I don't have the whole picture so I can't tell what the best solution would be.

#1381 should provide a nice way to achieve this.