The fetch_links=True in beanie queries doesn't work

[nemrok]

So after getting a document calling fetch_all_links() works however when using the keyword argument it doesn't. Thus you can't do queries comparing the linked document properties. For example the below would not work:

doc = await House.find_one(House.front_door.color == 'Blue', fetch_links=True)

[michaelkryukov]

This looks like same issue with mongomock's implementation of DBRef (which is the core of beanie's links) as discussed in #5. I've created issue at mongomock (mongomock/mongomock#759), but I don't really want to patch internals of mongomock in this library. So currently support for links is limited.

[nemrok]

Thanks so much! In the interim, I changed my code to use fetch_all_links in an async for loop and for cases where I need to use fetch_links I skipped these unit tests for now. I have integration tests to cover these cases. However it would be great to have this working.

[mahdiandev]

Hello, Can you fix this?
it shows NotImplementedError: Although 'pipeline' is a valid lookup operator for the aggregation pipeline, it is currently not implemented in Mongomock.

[michaelkryukov]

What exactly is not working for you? This issue refers to the internal implemetation of beanie that doesn't support some operations with DBRef that mongo supports (and beanie uses).

[martincpt]

We've solved this by not using fetch links when running unittest and implement a fallback like this.

doc = await Doc.find_one(
    # your expressions
    fetch_links=not settings.is_testing,
)

if settings.is_testing: # fallback
    await doc.fetch_alll_links()
    # or await doc.your_link.fetch() if you need one specific field only

Cheers.