Filtering on embedded document fields is not working

[draghuram]

Expected Behavior

I defined two resources "people" and "countries" with "people" containing a "data_relation' field of "countries" resource. When I query people as follows, the response doesn't contain any resources even though there should be some satisfying the criteria.

settings = {
    'RESOURCE_METHODS': ['GET', 'POST'],
    'ITEM_METHODS': ['GET', 'PATCH', 'DELETE'],
    'DOMAIN': {
        'people': {
            "schema": {
                "name": {
                    "type": "string"
                },
                "country": {
                    'required': True,
                    'type': 'objectid',
                    'data_relation': {
                        'resource': 'countries',
                        'field': '_id',
                        'embeddable': True
                    },
                }
            }
        },
        'countries': {
            "schema": {
                "name": {
                    "type": "string"
                },
            }
        }
    }
}

$ curl  'http://localhost:5000/people?where=\{"country.name":"US"\}'

Environment

• Python version: 3.8
• Eve version: Tested with latest release as well as master.

[draghuram]

The documentation at
https://docs.python-eve.org/en/stable/features.html#filtering
explicitly mentions that filtering on embedded documents is possible. I can debug this further and provide a fix (if required) so any pointers to the relevant code are appreciated.