Populate `{ModelName}Relations` through the CLI

[nabdelgadir]

Description / Steps to reproduce / Feature proposal

Once #2960 is landed, lb4 model will add a generic empty {ModelName}Relations interface to the model class file.

Cross-posting from #2960 (comment):

@bajtos:

Entries for individual relations would be added to {ModelName}Relations either manually by the application developer or by lb4 relation command.

Current Behaviour

lb4 model generates empty interface, e.g.:

export interface TodoRelations {}

lb4 relation does not add any navigational properties to this empty interface.

Expected Behaviour

• Enhance lb4 relation to populate {ModelName}Relations

Example:

export interface TodoRelations {
 todoList?: TodoListWithRelations;
}

export interface TodoListRelations {
  todos?: TodoWithRelations[];
  image?: TodoListImageWithRelations;
}

[dhmlau]

Not sure if I'm missing something. For the current lb4 relation flow,

• create the source and target models
• create the repositories for both
• run the lb4 relation command to specify the model relation.

But from the description of this issue, it seems like when we're running lb4 repository, we already have the relations defined?

[bajtos]

Entries for individual relations would be added to {ModelName}Relations either manually by the application developer or by lb4 repository command.

Ah, that was a typo on my side. I meant lb4 relation. Let me fix the issue description.

The problem is that at the momemt, lb4 model creates an empty {ModelName}Relations interface. When lb4 relations adds a new relation, it is not adding navigational properties to that interface, the developer has to update the interface manually. The goal of this user story is to fix that.