When my sharding key have two fields, loopback does not support to locate a model using two fields.

[elfahxh]

Bug or feature request

• [ x] Bug
• Feature request

Description of feature (or steps to reproduce if bug)

I created two Models, Model-B is an embedded model in Mode-A, Model-A must have sharding key which have two fields. When I call such related method, Model-A.Model-B.create(), will failed.
The root-cause is that, underline, it will call updateAttributes() of Model-A, while the search filter only have "_id" field, cannot define a combined multiple keys to find Model-A from database. hence, will encounter a failure.

Link to sample repo to reproduce issue (if bug)

Expected result

Actual result (if bug)

Additional information (Node.js version, LoopBack version, etc)

[jannyHou]

@elfahxh We have an issue to track "Supporting composite foreign key in loopback":
#2080

I migrated your comment to that issue and let's keep all discussion there. I am closing this issue as a dup. Thanks for understanding.