mongoose-autopopulate

mongoose-autopopulate

Always populate() certain fields in your mongoose schemas

Note: This plugin will only work with mongoose >= 4.0. Do NOT use this plugin with mongoose 3.x. You have been warned.

Note: population is a powerful feature, but it has limitations and helps you get away with poor schema design. In particular, it is usually bad MongoDB schema design to include arrays that grow without bound in your documents. Do not include a constantly-growing array of ObjectIds in your schema - your data will become unwieldy as the array grows and you will eventually hit the 16mb document size limit. In general, think carefully when designing your schemas.

API

The mongoose-autopopulate module exposes a single function that you can pass to the mongoose.Schema.prototype.plugin() function. Below you will see how to use this function.

Suppose you have two collections, "people" and "bands". The People model looks like this:

var personSchema = new Schema({ name: String, birthName: String });
Person = mongoose.model('people', personSchema, 'people');

Suppose your "people" collection has one document:

{
  name: 'Axl Rose',
  birthName: 'William Bruce Rose, Jr.',
  _id: '54ef3f374849dcaa649a3abc'
};

And your "bands" collection has one document:

{
  _id: '54ef3f374849dcaa649a3abd',
  name: "Guns N' Roses",
  lead: '54ef3f374849dcaa649a3abc',
  members: ['54ef3f374849dcaa649a3abc']
}

It supports an autopopulate option in schemas

You can set the autopopulate option for the lead field. This means that, every time you call find() or findOne(), mongoose-autopopulate will automatically call .populate('lead') for you.

    
    var bandSchema = new Schema({
      name: String,
      lead: { type: ObjectId, ref: 'people', autopopulate: true }
    });
    bandSchema.plugin(autopopulate);

    var Band = mongoose.model('band3', bandSchema, 'bands');
    Band.findOne({ name: "Guns N' Roses" }, function(error, doc) {
      assert.ifError(error);
      assert.equal('Axl Rose', doc.lead.name);
      assert.equal('William Bruce Rose, Jr.', doc.lead.birthName);
      done();
    });
  

It supports document arrays

mongoose-autopopulate also works on arrays.

    
    var bandSchema = new Schema({
      name: String,
      members: [{ type: ObjectId, ref: 'people', autopopulate: true }]
    });
    bandSchema.plugin(autopopulate);

    var Band = mongoose.model('band4', bandSchema, 'bands');
    Band.findOne({ name: "Guns N' Roses" }, function(error, doc) {
      assert.ifError(error);
      assert.equal('Axl Rose', doc.members[0].name);
      assert.equal('William Bruce Rose, Jr.', doc.members[0].birthName);
      done();
    });
  

It can specify an options argument

Advanced users of populate() may want to specify additional options, such as selecting fields. If you set the autopopulate option to an object, mongoose-autopopulate will merge the object into populate options. The findOne() below is equivalent to Band.findOne({ name: "Guns N' Roses" }).populate({ path: 'lead', select: 'name });

    
    var bandSchema = new Schema({
      name: String,
      lead: { type: ObjectId, ref: 'people', autopopulate: { select: 'name' } }
    });
    bandSchema.plugin(autopopulate);

    var Band = mongoose.model('band5', bandSchema, 'bands');
    Band.findOne({ name: "Guns N' Roses" }, function(error, doc) {
      assert.ifError(error);
      assert.equal('Axl Rose', doc.lead.name);
      assert.ok(!doc.lead.birthName);
      done();
    });
  

It can specify a function that returns options

You can also set the autopopulate option to be a function. Then mongoose-autopopulate will call the function with the query object as the context and use the return value. The below populate() uses the same options as the previous example.

    
    var numCalls = 0;
    var optionsFunction = function() {
      ++numCalls;
      return { select: 'name' };
    };

    var bandSchema = new Schema({
      name: String,
      lead: { type: ObjectId, ref: 'people', autopopulate: optionsFunction }
    });
    bandSchema.plugin(autopopulate);

    var Band = mongoose.model('band6', bandSchema, 'bands');
    Band.find({ name: "Guns N' Roses" }, function(error, docs) {
      assert.ifError(error);
      assert.equal(1, docs.length);
      assert.equal(1, numCalls);
      var doc = docs[0];
      assert.equal('Axl Rose', doc.lead.name);
      assert.ok(!doc.lead.birthName);
      done();
    });