Missing `models/index.ts` after running `lb4 openapi` command

[dhmlau]

After running the lb4 openapi command, models are created. However, there is no index.ts file in the models folder. If I generate the repository for the model, it will get an error during build:

src/repositories/pet.repository.ts:2:33 - error TS2307: Cannot find module '../models'.

2 import {Pet, PetRelations} from '../models';
                                  ~~~~~~~~~~~

It's not a big issue because I can create the index.ts, but generating the index.ts when generating the models would be helpful.

Steps to reproduce

1. In a LB application, run

lb4 openapi https://raw.githubusercontent.com/OAI/OpenAPI-Specification/master/examples/v3.0/petstore-expanded.yaml

2. It creates the Pet and NewPet and Error model.
3. Create datasource and Repository
4. Run npm run build.
   It gives the error I've shown above because of the missing index.ts to export the models.
   UPDATED: it also complained about PetRelations not imported in the repository class but it actually doesn't exist.

Acceptance Criteria

• Generate the index.ts model file during lb4 openapi
• the generated code should not have any build error. (about the missing {ModelName}Relations)

[raymondfeng]

Interesting. Maybe it's a regression? The index files should be updated by calling https://github.com/strongloop/loopback-next/blob/master/packages/cli/lib/artifact-generator.js#L127

[dhmlau]

I'm using the latest version of @loopback/cli. Just tried it again to make sure, it doesn't generate the index.ts.

[dhmlau]

After I added the index.ts in models folder, I realized that PetRelations does not exist but the repository class is referencing it.

I've put my project in https://github.com/dhmlau/openapi-test.