Trigger listeners cannot handle models with custom db_column attribute

[PaulGilmartin]

See #19 for more

[PaulGilmartin]

Issue comes from the fact that a Notification coming from a trigger sends a payload built as follows:

    def _build_payload(self, model):
        return  f'''
            payload := json_build_object(
                'app', '{model._meta.app_label}',
                'model', '{model.__name__}',
                'old', row_to_json(OLD),
                'new', row_to_json(NEW)
              );
        '''

Here, OLD and NEW will build JSON according to the columns as they're stored in the database (i.e. will use the db_column value on a ForeignKey if set). We then attempt to deserialise that value in the TriggerPayload class in order to build the old and new arguments to our trigger based listener. Our deserialisation method looks as follows:

class TriggerPayload:
    def __init__(self, payload: Dict):
        self._json_payload = payload
        self._model = apps.get_model(
            app_label=self._json_payload['app'],
            model_name=self._json_payload['model'],
        )
        self._old_row_data = self._json_payload['old']
        self._new_row_data = self._json_payload['new']

    @property
    def old(self):
        if self._old_row_data:
            return self._model(**self._old_row_data)

The error comes in the line self._model(**self._old_row_data): since self._old_row_data was built by the aformentioned trigger payload (which uses the database column names), if a model has a FK attribute which does not match the corresponding db column name, we'll get an error like

 Encountered exception Author() got unexpected keyword arguments: 'some_other_column_name'

[PaulGilmartin]

This has been fixed in #34 and is available in v1.0.5