include for role mappings to different principalTypes

[nvdnkpr]

I read through the issues, the tests and the docs but I couldn't find a word about the possibility to e.g. include all users (but not applications or roles) of a role.

I found issue #332 but

1. the code described there only works if we change the return call to callback (as described by @haohello)

2. even if it is working, what would be the best next step to embed user objects in the roles ?

[raymondfeng]

I think we should try to leverage http://docs.strongloop.com/display/LB/Polymorphic+relations.

[nvdnkpr]

I'm currently building my app with LB1 but I have an on LB2 with migration in my mind. I already read about the polymorphic relations, but their aren't used yet in the Role -> RoleMapping -> User/Application/Role Model. Any ETA ?

[nvdnkpr]

If I extend Role and RoleMapping (I already have an extended User model) can I then already model it with the polymorphic relations ?

[raymondfeng]

You should be able to override the relations. Can you give a try and let us know?

[nvdnkpr]

It works... I managed to extend Application, User, Role and RoleMapping in the following way:
(Class with "My" prefix are the extension)

    MyApplication.hasAndBelongsToMany(MyRole, { through: MyRoleMapping, polymorphic: 'principal' });
    MyUser.hasAndBelongsToMany(MyRole, { through: MyRoleMapping, polymorphic: 'principal' });

    // optional inverted relations
    MyRole.hasMany(MyApplication, {through: MyRoleMapping, polymorphic: 'principal', invert: true});
    MyRole.hasMany(MyUser, {through: MyRoleMapping, polymorphic: 'principal', invert: true});

and it worked since I got the following methods on the following classes:
on MyUser: __[findById, destroyById, ...]__roles, …
on MyApplication: __[findById, destroyById, ...]__roles, …
on MyRole: __[__findById, destroyById]__applications, …

so it seem to work on the model level.
But they don't show up in the Explorer, although e.g.
MyApplication.sharedClass.find('__findById__roles', false).shared is true.

I guess that comes from the fact that the classes' relations were added "after" they were published.

Is there a way to republish all published classes ?

[raymondfeng]

Cool.

1. I think we'll probably remodel role/rolemapping using ploymorphic relations.
2. Where did you set up the relations?
3. Expose new models created after the explorer is initiated loopback-component-explorer#22

[nvdnkpr]

I extended Role, Application, User and RoleMapping, prefixed the new models with "My" and set up the relations entirely in MyRole using the code below (it's my MyRole.js)

/*
  Module dependencies
*/
var _ = require('underscore');
var util = require('util')
var debug = require('debug')('myapp:models:MyRole');

module.exports = function(MyRole){
  MyRole.on('dataAccessConfigured',
    function(MyRole){
      process.nextTick(function(){
        // retrieve app model registry
        var models = MyRole.app.models;
        // get MyApplication and MyUser
        var MyRoleMapping = models.MyRoleMapping;
        var MyApplication = models.MyApplication;
        var MyUser = models.MyUser;

        //
        MyApplication.hasAndBelongsToMany(MyRole, { through: MyRoleMapping, polymorphic: 'principal' });
        MyUser.hasAndBelongsToMany(MyRole, { through: MyRoleMapping, polymorphic: 'principal' });

        // optional inverted relations
        MyRole.hasMany(MyApplication, {through: MyRoleMapping, polymorphic: 'principal', invert: true});
        MyRole.hasMany(MyUser, {through: MyRoleMapping, polymorphic: 'principal', invert: true});
      });
    });
};

By the way:
As you can see I still had the problem that was reported was by coodoo in #410 and by me in #425. The relations on the show up in explorer but not on the model when listening for 'dataAccessConfigured' (I guess that was the "new" event to listen to to be notified that all models are ready to go.). I solved that by using process.nextTick().

This could possibly be my problem for the current situation that it works on the model level but is not shown in the loopback-explorer.

[nvdnkpr]

Regarding 3.
How can I get that to work ? Your PR seemed to have failed, so what is the event to listen on with the loopback-explorer ?

[raymondfeng]

You should listen dataSourceAttached which will be emitted after dataAccessConfigured.

[nvdnkpr]

I changed the listener to dataSourceAttached, but I still need the process.nextTick to access the methods. The code I wrote for the polymorphic relations does not work without the process.nextTick. Without it I get a TypeError: Cannot read property 'models' of undefined Error

[nvdnkpr]

It seems the polymorphic relations arent that stable after all. I posted a new issue, see #446

[nvdnkpr]

After #446 being closed, I managed (succesfully) to model the polymorphic relation (which btw still needed a process.nextTick to work:

MyRole.on('dataSourceAttached',function(){process.nextTick(function(){
    var app = MyRole.app;
    // get MyApplication and MyUser
    var RoleMapping = app.models.MyRoleMapping;
    var Application = app.models.MyApplication;
    var User = app.models.MyUser;

    //
    Application.hasAndBelongsToMany(MyRole, { through: RoleMapping, polymorphic: 'principal'});
    User.hasAndBelongsToMany(MyRole, { through: RoleMapping, polymorphic: 'principal'});

    // optional inverted relations
    MyRole.hasMany(Application, {through: RoleMapping, polymorphic: 'principal', invert:true});
    MyRole.hasMany(User, {through: RoleMapping, polymorphic: 'principal', invert:true});
});});

Then I tried to model the same relationship via the JSON files using

{
  "name": "[MyUser|MyApplication]",
  "base": "[User|Application]",
  "relations":{
    "roles":{
      "model": "MyRole",
      "type": "hasAndBelongsToMany",
      "through": "MyRoleMapping",
      "polymorphic": "principal",
    }
  }
}

and the appropriate relation modeling on MyRole:

{
  "name": "MyRole",
  "plural": "roles",
  "base": "Role",
  "relations": {
    "applications":{
      "model": "MyApplication",
      "type": "hasMany",
      "through": "MyRoleMapping",
      "polymorphic": "principal",
      "invert":true
    },
    "users":{
      "model": "MyUser",
      "type": "hasMany",
      "through": "MyRoleMapping",
      "polymorphic": "principal",
      "invert":true
    },
  },
}

but that created a wrong data model for MyRoleMapping (id, principalType, principalId, applicationId, userId, roleId).

Did I model it wrong or is this just another bug ? If so tell me, I'm going to open another issue ;)

[superkhau]

@raymondfeng Is this still relevant?