Search for one-to-many relationship fails saying 'has()' not implemented for collections. Use any().

[hussaintamboli]

class Product(Model):
    __tablename__ = 'product'
    ...
    usecase = relationship("ProductUsecaseMapping", cascade="save-update", lazy="joined")

class ProductUsecaseMapping(Model):
    __tablename__ = 'product_usecase_mapping'
    product_id = Column(String(36), ForeignKey('product.id'))
    usecase_id = Column(Integer, ForeignKey('usecase.id'))
    ....

filter_for_searching_specific_products = {
    'filter': {
        'country_code': kwargs.pop('country'),
        'category': kwargs.get('search_type'),
        'usecase.usecase_id': {
            'in': [kwargs.pop('usecase')]
        }
    }
}

It works for one-to-one relationship but not with one-to-may. With above filter I get an error saying -

'has()' not implemented for collections.  Use any().

[mikebarkmin]

I have played around a little and came up with this solution:

    def create_query(self, attr):
        """ Mix all values and make the query """
        field = attr[0]
        operator = attr[1]
        value = attr[2]
        model = self.model

        if "." in field:
            field_items = field.split(".")

            attr = None
            for field_item in field_items:
                attr = getattr(model, field_item, None)
                if isinstance(attr.property, RelationshipProperty):
                    model = attr.property.mapper.class_
                    self.model_query = self.model_query.join(model)
                else:
                    break

            return OPERATORS[operator](attr, value)

        return OPERATORS[operator](getattr(model, field, None), value)

With this one-to-many and many-to-many filters should work. It should also work as deep as you like.

See here for the whole implementation: https://gitlab.com/openpatch/flask-core/-/blob/master/openpatch_core/database/elastic_query.py