Waterline: Using attributes in join table

Group.js

/**
* Group.js
*
* @description :: TODO: You might write a short summary of how this model works and what it represents here.
* @docs        :: http://sailsjs.org/#!documentation/models
*/

module.exports = {

  attributes: {

    name : { type: 'string' },

    description : { type: 'string' },

    products: {
      collection: 'productGroup',
      references: 'productGroup',
      on: 'groupid',
      via: 'productid',
      unique: true
    }
  },

  findWithProductPriority: function (cb) {
    
    Group.find({sort: { groupid: 1, prodPriority: 1 }})
      .populate('products')
      .exec(cb);
  }

};

Product.js

/**
* Product.js
*
* @description :: TODO: You might write a short summary of how this model works and what it represents here.
* @docs        :: http://sailsjs.org/#!documentation/models
*/

module.exports = {

  autoPK: false,

  attributes: {

    uuid : {
      type: 'string',
      primaryKey: true,
      required: true
    },

    name : {
      type: 'string',
      required: true,
    },

    description : {
      type: 'string',
      required: true
    },

    photos : { type: 'json' },

    price : {
      type: 'float',
      required: true
    },

    avail_modifiers : {
      type: 'array',
      required: true
    },

    unit : {
      type: 'string',
      enum: ['item', 'kg'],
      defaultsTo: 'item'
    },

    groups: {
      collection: 'productGroup',
      references: 'productGroup',
      on: 'productid',
      via: 'groupid',
    }
  }
};

ProductGroup.js

module.exports = {
  identity      : 'ProductGroup',
  tableName     : 'product_group',

  attributes : {

    // Due to a bug in the schema generator this seems to be needed at the
    // model level but not on the actual database.
    // id: {
    //   type: 'integer',
    //   primaryKey: true
    // },

    productid : {
      columnName: 'product_id',
      type: 'integer',
      foreignKey: true,
      references: 'product',
      on: 'id',
      groupKey: 'product'
    },

    groupid : {
      model: 'group',
      columnName: 'group_id',
      type: 'integer',
      foreignKey: true,
      references: 'group',
      on: 'id',
      groupKey: 'group'
    },

    prodPriority: {
      type: 'integer'
    }

  }

};