Mongoose Schema: Forcing an array of objects to be created

Question

My Mongoose schema looks like this:

var userSchema = mongoose.Schema({

  fbid       : String,
  googleid   : String,
  birthday   : String,
  email      : String,
  first_name : String,
  last_name  : String,
  gender     : String,
  age        : Number,
  location   : String,
  paid       : { type: Boolean, default: 0 },
  lessons: [
    { 
      name    : { type: String,  default: 'foobar1'},
      sent    : { type: Boolean, default: 0 },
      read    : { type: Boolean, default: 0 },
      activity: { type: Boolean, default: 0 }
    },
    { 
      name    : { type: String,  default: 'foobar2'},
      sent    : { type: Boolean, default: 0 },
      read    : { type: Boolean, default: 0 },
      activity: { type: Boolean, default: 0 }
    },
    { 
      name    : { type: String,  default: 'foobar3'},
      sent    : { type: Boolean, default: 0 },
      read    : { type: Boolean, default: 0 },
      activity: { type: Boolean, default: 0 }
    },
    { 
      name    : { type: String,  default: 'foobar4'},
      sent    : { type: Boolean, default: 0 },
      read    : { type: Boolean, default: 0 },
      activity: { type: Boolean, default: 0 }
    },
    { 
      name    : { type: String,  default: 'foobar5'},
      sent    : { type: Boolean, default: 0 },
      read    : { type: Boolean, default: 0 },
      activity: { type: Boolean, default: 0 }
    },
    { 
      name    : { type: String,  default: 'foobar6'},
      sent    : { type: Boolean, default: 0 },
      read    : { type: Boolean, default: 0 },
      activity: { type: Boolean, default: 0 }
    },
    { 
      name    : { type: String,  default: 'foobar7'},
      sent    : { type: Boolean, default: 0 },
      read    : { type: Boolean, default: 0 },
      activity: { type: Boolean, default: 0 }
    },
    { 
      name    : { type: String,  default: 'foobar8'},
      sent    : { type: Boolean, default: 0 },
      read    : { type: Boolean, default: 0 },
      activity: { type: Boolean, default: 0 }
    } 
  ]

});

When doing new User(), everything is created properly except for the lessons array, which returns as an empty array rather than creating the nested objects with their default values.

It is possible to make these objects when doing new User(), but I want this to occur in the model itself as all users will have the same lessons and same initial values.

How can I make this happen?

Answer 1

Set default value in your schema declaration:

var defaultLessons = [
    { 
      name    : 'foobar1',
      sent    : 0 ,
      read    : 0 ,
      activity: 0 
    ,
    { 
      name    : 'foobar2',
      sent    : 0 ,
      read    : 0 ,
      activity: 0 
    ,
    { 
      name    : 'foobar3',
      sent    : 0 ,
      read    : 0 ,
      activity: 0 
    ,
    { 
      name    : 'foobar4',
      sent    : 0 ,
      read    : 0 ,
      activity: 0 
    ,
    { 
      name    : 'foobar5',
      sent    : 0 ,
      read    : 0 ,
      activity: 0 
    ,
    { 
      name    : 'foobar6',
      sent    : 0 ,
      read    : 0 ,
      activity: 0 
    ,
    { 
      name    : 'foobar7',
      sent    : 0 ,
      read    : 0 ,
      activity: 0 
    ,
    { 
      name    : 'foobar8',
      sent    : 0 ,
      read    : 0 ,
      activity: 0 
    } 
  ];

var userSchema = new mongoose.Schema({
  ...
  lessons: { type: [], default: defaultLessons}
});

Another more structure way is to use sub docs:

var lessonSchema = new mongoose.Schema({                                                                         
  name    : { type: String,  default: 'foobar'},
  sent    : { type: Boolean, default: 0 },
  read    : { type: Boolean, default: 0 },
  activity: { type: Boolean, default: 0 }
});

var defaultLessons = [ 
    {  
      name    : 'foobar1', 
    }, 
    {  
      name    : 'foobar2', 
    }, 
    {  
      name    : 'foobar3', 
    }, 
    {  
      name    : 'foobar4', 
    }, 
    {  
      name    : 'foobar5', 
    }, 
    {  
      name    : 'foobar6', 
    }, 
    {  
      name    : 'foobar7', 
    }, 
    {  
      name    : 'foobar8', 
    }  
  ];

var userSchema = new mongoose.Schema({
  ...
  lessons: { type: [lessonSchema], default: defaultLessons}
});

However, above does not work in mongoose 4+, I've tried mongoose 3.8 ok. See this discussion.

Answer 2

Following link would be helpful for setting default values for nested Array in mongoose Schema.

set default values to mongoose arrays in node js

You could do like this:

var lessonSchema = Schema({
    name: { type: String },
    sent: { type: Boolean },
    read: { type: Boolean },
    activity: { type: Boolean }
});

var userSchema = Schema({
    fbid: { type: String },
    googleid: { type: String },
    birthday: { type: String },
    email: { type: String },
    first_name: { type: String },
    last_name: { type: String },
    gender: { type: String },
    age: { type: Number },
    location: { type: String },
    paid: { type: Boolean, default: 0 },
    lessons: [lessonSchema]
});

userSchema.pre("save", function (next) {
    if (!this.lessons || this.lessons.length == 0) {
        this.lessons = [];
        this.lessons.push({
            "name": "football 1",
            "sent": true,
            "read": true,
            "activity": true
        })

         this.lessons.push({
            "name": "football 2",
            "sent": true,
            "read": true,
            "activity": true
        })

         this.lessons.push({
            "name": "football 3",
            "sent": true,
            "read": true,
            "activity": true
        })

         this.lessons.push({
            "name": "football 3",
            "sent": true,
            "read": true,
            "activity": true
        })
    }
    next();
});

Answer 3

You could add a pre save hook in your schema

schema.pre('save', function(next) {
  if (this.isNew) {
    this.set('lessons', [ ... ]);
  }
  next();
});

More info here http://mongoosejs.com/docs/middleware.html