[SOLVED] Retrieve the subset of fields by querying the embedded field

Retrieve the subset of fields by querying the embedded field

Is it possible to retrieve the subset of fields using Django mongodb nonrel. I am totally new to python, but have good knowledge in mongo.

My requirement is very straight forward, I wanted to query the collection by its embedded field and return only some specific fields

I could do that in mongodb by

db.Contract.find({'owner.name':'Ram'},{'address':1})

and I tried this in django

Contract.objects.filter(owner__name='Ram')

but it throws an error

raise FieldError("Join on field %r not permitted. Did you misspell %r for the lookup type?" % (name, names[pos + 1])) FieldError: Join on field 'owner' not permitted. Did you misspell 'name' for the lookup type?

am totally struck here. I believe i have my models as specified in the documentation.

class SimplePerson(models.Model):
    name = models.CharField(max_length=255)
    user_key = models.CharField(max_length=255)


class Contract(models.Model):
    owner = EmbeddedModelField('SimplePerson')
    title = models.CharField(max_length=120, )

This is really weird. I could't find any reference in the documentation site about how to query the embedded field & retrieve the subset of fields.

Finally I used raw_query to query the embedded field

Contract.objects.raw_query({'owner.name':'Ram'})

But still not able to figure out how to retrieve the subset of fields. Can someone help me out?

Solution

Subobject filters aren't possible yet so you need to drop down to raw_query (which you already figured out). To retrive a subset of fields, use .values('field1', 'field2', ...).