* .add( primary key )

Purpose

Used to add records to the join table that is automatically generated during a Many-to-Many association. It accepts either the primary key of the model instance (defaults to record ID) or a new record (object) that you want created and to be associated with.

Overview

Parameters

Example Usage

User.find({name:'Mike'}).populate('pets').exec(function(e,r){
  r[0].pets.add(7);
  r[0].save(function(err,res){
    console.log(res);
  }
});

/*

{ pets:
   [ { name: 'Pinkie Pie',
       color: 'pink',
       id: 7,
       createdAt: Wed Feb 12 2014 18:06:50 GMT-0600 (CST),
       updatedAt: Wed Feb 12 2014 18:06:50 GMT-0600 (CST) },
     { name: 'Rainbow Dash',
       color: 'blue',
       id: 8,
       createdAt: Wed Feb 12 2014 18:06:50 GMT-0600 (CST),
       updatedAt: Wed Feb 12 2014 18:06:50 GMT-0600 (CST) },
     { name: 'Applejack',
       color: 'orange',
       id: 9,
       createdAt: Wed Feb 12 2014 18:06:50 GMT-0600 (CST),
       updatedAt: Wed Feb 12 2014 18:06:50 GMT-0600 (CST) } ],
  name: 'Mike',
  age: 16,
  createdAt: Wed Feb 12 2014 18:06:50 GMT-0600 (CST),
  updatedAt: Wed Feb 12 2014 19:30:54 GMT-0600 (CST),
  id: 7 }

*/

Notes

• .add() does not accept arrays of any kind. Don't try it.
• Any string arguments passed must be the primary key of the record.
• .add() alone won't actually persist the change in associations to the databse. You should call .save() after using .add() or .remove().
• Attempting to add an association that already exists will throw an error. See here for an example.