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mongoose-autopopulate plugin

It supports an autopopulate option in schemas

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']
}

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 has a couple caveats with projections

By default, Mongoose 5.x automatically projects in populated properties. That means you need a little extra work to exclude autopopulated fields. Either explicitly deselect the path in your projection, or set the selectPopulatedPaths schema option to false.

// Mongoose adds `members: 1` and `lead: 1` to the projection
let band = yield Band.findOne().select({ name: 1 });
assert.equal(band.members[0].name, 'Axl Rose');
assert.equal(band.lead.name, 'Axl Rose');

// You can also tell Mongoose to not project in populated paths by default
// using the `selectPopulatedPaths` schema option.
const newSchema = Band.schema.clone();

newSchema.options.selectPopulatedPaths = false;
let Band2 = mongoose.model('Band2', newSchema, 'bands');

band = yield Band2.findOne().select({ name: 1 });
assert.ok(!band.members);
assert.ok(!band.lead);

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();
});

It can disable autopopulate for individual queries

If you set the autopopulate option to false on a query, autopopulate will be disabled. This is handy if you want to autopopulate by default, but opt-out for special cases.

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

var Band = mongoose.model('band7', bandSchema, 'bands');
Band.findOne({ name: "Guns N' Roses" }, {}, { autopopulate: false }, function(error, doc) {
  assert.ifError(error);
  assert.ok(doc.lead instanceof mongoose.Types.ObjectId);
  assert.ok(!doc.populated('lead'));
  done();
});

It can disable autopopulate in populate() options

Say you have a model User that has the autopopulate plugin and you're populating users from a different model. To disable autopopulate, you need to set autopopulate: false as a populate option, not a query option.

const userSchema = new Schema({
  name: String,
  friends: [{
    type: Schema.Types.ObjectId,
    ref: 'User',
    autopopulate: { maxDepth: 2 }
  }]
});
userSchema.plugin(autopopulate);

const responseSchema = new Schema({
  user: {
    type: Schema.Types.ObjectId,
    ref: 'User'
  }
});

const User = mongoose.model('User', userSchema);
const Response = mongoose.model('Response', responseSchema);

return co(function*() {
  const axl = new User({ name: 'Axl' });
  const slash = new User({ name: 'Slash', friends: [axl._id] });
  axl.friends.push(slash._id);

  yield [axl.save(), slash.save()];
  let r = yield Response.create({ user: axl._id });

  r = yield Response.findById(r._id).
    // Because `User` is the foreign model, you need to disable autopopulate
    // in the populate options below, not the query options
    populate({ path: 'user', options: { autopopulate: false } });
});

It requires an option to work with lean

Setting the Mongoose lean option will disable autopopulate for all paths, unless you add autopulate: true to your lean option.

// acquit:ignore:start
return co(function*() {
  // acquit:ignore:end
  let band = yield Band.findOne().lean();
  // Won't autopopulate because `lean()` is set
  assert.ok(band.lead instanceof mongoose.Types.ObjectId);

  // To turn on `autopopulate` with lean, use `lean({ autopulate: true })`
  band = yield Band.findOne().lean({ autopopulate: true });
  assert.equal(band.lead.name, 'Axl Rose');

It can limit the depth using maxDepth

Recursive populate can lead to messy infinite recursion, so this plugin supports a maxDepth option that limits how deep recursive population will go. The maxDepth option is 10 by default

return co(function*() {
  const accountSchema = new mongoose.Schema({
    name: String,
    friends: [{
      type: mongoose.Schema.Types.ObjectId,
      ref: 'Account',
      // This is a recursive relationship, `friends` points to a list
      // of accounts. If we didn't limit the depth, this would result
      // in infinite recursion!
      autopopulate: { maxDepth: 2 }
    }]
  });
  accountSchema.plugin(autopopulate);

  const Account = mongoose.model('Account', accountSchema);

  const axl = new Account({ name: 'Axl' });
  const slash = new Account({ name: 'Slash', friends: [axl._id] });
  axl.friends.push(slash._id);

  yield axl.save();
  yield slash.save();

  const doc = yield Account.findById(axl._id);

  assert.equal(doc.friends[0].name, 'Slash');
  assert.equal(doc.friends[0].friends[0].name, 'Axl');
  // Only populate 2 levels deep, 3rd level will still be an `_id`
  assert.equal(doc.friends[0].friends[0].friends[0].toString(),
    slash._id.toHexString());
});

It can pass a list or regular expression of functions to apply hooks to

By default, autopopulate applies to the results of find(), findOne(), findOneAndUpdate(), and save(). You can pick which functions you want autopopulate to handle using the functions option. For example, the below code disables autopopulating on save().

return co(function*() {
  const bandSchema = new Schema({
    name: String,
    lead: { type: ObjectId, ref: 'people', autopopulate: true }
  });
  bandSchema.plugin(autopopulate, {
    // Apply this plugin to all functions except for `save()`
    functions: ['find', 'findOne', 'findOneAndUpdate']
  });
  
  const Band = mongoose.model('band8', bandSchema, 'bands');

  let band = yield Band.findOne({ name: "Guns N' Roses" });
  assert.ok(band.populated('lead'));

  band = yield Band.findOne({ name: "Guns N' Roses" }).setOptions({ autopopulate: false });
  assert.ok(!band.populated('lead'));
  // `save()` doesn't autopopulate
  yield band.save();
  assert.ok(!band.populated('lead'));
});