Model relations

[arash01]

I was wondering if model relations are implemented in current version or not yet?
I see some decorators such as @ belongsTo in source code but couldn't find any documentation about using them.

[shimks]

Currently there is no implementation for model relations. To stay up-to-date on its release, please follow #537.

[arash01]

I wish we had this feature on current release because without model relations, it's almost impossible for me to continue developing and testing on Loopback-Next :(

[arash01]

Also as a friendly suggestion, please don't close an issue as soon as you post a reply. Keeping an issue open for short period of time gives opportunity to other users to be involved in discussion.

[bajtos]

I'd like to reopen this issue.

In #537, we reached the conclusion that we are going to keep Juggler around, but we would like to eventually simplify both the features provides and the codebase. In that light I think it makes sense to discuss how to expose relations in LoopBack 4.

Here is my understanding of the current status:

• Decorators like @belongsTo are just dummy placeholders not doing anything.
• We don't have any helpers for exposing relation methods via REST API (or gRPC, etc.)

IMO, in order to make relations happen, two changes are needed:

1. Build Repository classes for accessing related models, passing metadata from @belongsTo (and friends) to legacy juggler. For example, our DefaultCrudRepository creates a new backing PersistedModel from the definition provided by an Entity(a Model) annotated with decorators like @property. (source code).

2. Come up with a convention for building Controller classes exposing relation methods via REST API. See [WIP] [RFC] feat: Add REST mapping for repository interfaces #740 for an inspiration. Eventually, there should be a CLI tool for generating these controllers whenever an app developer is adding a new relation.

@arash01 I am afraid support for relations is pretty down in our priority list. Would you like to contribute this feature yourself? We are happy to help you along the way.

[arash01]

Thanks for reply. I'm not sure if my TypeScript knowledge is enough to contribute in this project.

[dhmlau]

@arash01 , we've opened a github issue on the spike: #995.

[dhmlau]

Duplicate of #995