AttributeError when initializing embedded documents

[hannes-brt]

When I initialize an instance of an EmbeddedDocument subclass, I get an AttributeError for the non-existing attribute _auto_id_field.

It works fine when I comment out

        # If its an automatic id field then skip to the first defined field
        if self._auto_id_field:
            next(field)

in mongoengine.base.document.

[rozza]

Could you provide a test case?

[redspider]

I replicated this particular error:

from mongoengine import *

class Foo(EmbeddedDocument):
    a = StringField()
    b = StringField()

Foo('cat','dog')

Note that while this gives you exactly the above error, it seems it's actually incorrect usage, Foo should be instantiated by:

Foo(a='cat', b='dog')

Instead. I just ran into this and thought it was worth adding to this discussion since it may help hannes-brt or other people who run into that somewhat cryptic error.

[MRigal]

Maybe covered by PR #777 ?

[Garito]

if hasattr(self, '_auto_id_field'):
  if self._auto_id_field:
    next(field)

could be written like

if hasattr(self, '_auto_id_field') and self._auto_id_field:
  next(field)

[Garito]

or even better

if gettattr(self, '_auto_id_field', False):
  next(field)

[shushen]

This problem is still biting. The analysis by @redspider hits the target and all following suggestion and PR #777 works to fix the problem.

@rozza, this would be a valid test case I extracted from discussion in PR #777:
Works:

    class EventRaw(EmbeddedDocument):
        data = ListField()
        timestamp = DateTimeField(default=datetime.datetime.now)

    class Events(Document):
        events = ListField(EmbeddedDocumentField(EventRaw))
        date = DateTimeField(default=datetime.datetime.now)

    Events(events=[EventRaw(data=["name", "type"])]).save()

Doesn't work:

    class EventRaw(EmbeddedDocument):
        data = ListField()
        timestamp = DateTimeField(default=datetime.datetime.now)

    class Events(Document):
        events = ListField(EmbeddedDocumentField(EventRaw))
        date = DateTimeField(default=datetime.datetime.now)

    Events([EventRaw(["name", "type"])]).save()

Note that the latter has only positional args, thus triggers the problematic code branch.

[lafrech]

To my understanding, the solution proposed in #777 makes total sense.

@shushen (or anyone else), would you like to provide a PR based on latest master the following?

• this fix (you may write it if gettattr(self, '_auto_id_field', False): as suggested by @Garito)
• a non-reg test added to the tests (inspired/copied from your post)
• maybe a note in the changelog
• yourself added to the contributors

Thanks.

[shushen]

Thanks @lafrech. Will submit a pull request soon.