gistfile1.txt

var User = function () {
  this.hasMany('Messages');
  this.hasMany('Conversations', {through: 'Messages'});
};
 
var Conversation = function () {
  this.hasMany('Memberships');
  this.hasMany('Users', {through: 'ConversationMemberships'});
};
 
var Message = function () {
  this.belongsTo('Users');
  this.belongsTo('ConversationMembership');
};

var ConversationMembership = function () {
  this.belongsTo('User');
  this.belongsTo('Conversation');
};