unable to access gridfs in a different database

[spitzbubchen]

I've been accessing my other database just fine using db_alias for most collections that do not contain FileField() or ImageField() fields. However, for collections with FileField() or ImageField() I have not been able to access the file in the other database. Does db_alias not properly link fs.files and fs.chunks in the other database? Must one somehow add meta = {"db_alias": "OtherDB"} to fs.files and fs.chunks?

class File(db.Document):
     file = db.ImageField()
     meta = {"db_alias": "OtherDB"}

for i in File.objects.all():
     print i.file          # Shows '<ImageGridFsProxy: (no file)>'
     print i.file.length   # Shows 'AttributeError'

[spitzbubchen]

Searching through mongoengine issues reports on github I came across one that gave me a hint. Basically, for FileField() or ImageField() it is necessary to place db_alias directly into the field. For example, this works:

class File(db.Document):
     file = db.ImageField(db_alias="OtherDB")

It would nice if the documentation was more clear on this, otherwise feel free to close this issue.

[mlorenc227]

Thanks a lot for reporting this! I spent whole day scratching my head trying to figure out why mongoengine couldn't retrieve the files in some contexts. This should definitely be documented.