Mongoose index

// drop indexes
db.accounts.dropIndex( { "tax-id": 1 } )
db.collection.dropIndexes()

Mongoose populate

// how to design schema and populate
var PersonSchema = new Schema({
  name    : String,
  age     : Number,
  stories : [{ type: Schema.ObjectId, ref: 'Story' }]
})
var StorySchema = new Schema({
  _creator : { type: Schema.ObjectId, ref: 'Person' },
  title    : String,
  fans     : [{ type: Schema.ObjectId, ref: 'Person' }]
})
var Story  = mongoose.model('Story', StorySchema)
var Person = mongoose.model('Person', PersonSchema)

var aaron = new Person({name: 'Aaron', age: 100})
aaron.save(function (err) {
  if (err) throw err

  var story1 = new Story({
    title: 'A man who cooked Nintendo',
    _creator: aaron._id
  })

  story1.save(function (err) {
    if (err) throw err;

    aaron.stories.push(story1._id)

    aaron.save(function (err) {
      if (err) throw err;

      Person
        .findOne({name: 'Aaron'})
        .populate('stories')
        .run(function (err, person) {
          if (err) throw err

          console.log('person =', person)
          console.log('person.stories =', person.stories[0])
      })

      Story
        .findOne({title: /Nintendo/i})
        .populate('_creator')
        .run(function (err, story) {
          if (err) throw err
          console.log('story =', story)
      })
    })
  })
})

// person = {
//   stories: [ [object Object] ],
//   name: 'Aaron',
//   age: 100,
//   _id: 4e56698f15dff83410000001
// }

// person.stories = {
//   fans: [ ],
//   _id: 4e56698f15dff83410000002,
//   _creator: 4e56698f15dff83410000001,
//   title: 'A man who cooked Nintendo'
// }

// story = {
//   fans: [ ],
//   _id: 4e56698f15dff83410000002,
//   _creator:
//    { stories: [ 4e56698f15dff83410000002 ],
//      name: 'Aaron',
//      age: 100,
//      _id: 4e56698f15dff83410000001 },
//   title: 'A man who cooked Nintendo'
// }

// populates a single object
User.findById(id, function (err, user) {
  var opts = [
      { path: 'company', match: { x: 1 }, select: 'name' }
    , { path: 'notes', options: { limit: 10 }, model: 'override' }
  ]

  User.populate(user, opts, function (err, user) {
    console.log(user);
  })
})

// populates an array of objects
User.find(match, function (err, users) {
  var opts = [{ path: 'company', match: { x: 1 }, select: 'name' }]

  var promise = User.populate(users, opts);
  promise.then(console.log).end();
})

// imagine a Weapon model exists with two saved documents:
//   { _id: 389, name: 'whip' }
//   { _id: 8921, name: 'boomerang' }

var user = { name: 'Indiana Jones', weapon: 389 }
Weapon.populate(user, { path: 'weapon', model: 'Weapon' }, function (err, user) {
  console.log(user.weapon.name) // whip
})

// populate many plain objects
var users = [{ name: 'Indiana Jones', weapon: 389 }]
users.push({ name: 'Batman', weapon: 8921 })
Weapon.populate(users, { path: 'weapon' }, function (err, users) {
  users.forEach(function (user) {
    console.log('%s uses a %s', users.name, user.weapon.name)
    // Indiana Jones uses a whip
    // Batman uses a boomerang
  })
})
// Note that we didn't need to specify the Weapon model because
// we were already using it's populate() method.

Mongoose query.js

// query
db.users.find({age: {$gte: 18, $lte: 30}}) // lt,gt
db.users.find({age: {$in: [12, 'ud']]}}) // $nin
db.food.insert({'fruit': ['apple', 'banana', 'peach']})
db.food.find({'fruit': 'apple'}) // match docs that have apple in it
db.food.find({'fruit': {$all: ['apple', 'banana']}) // match docs that have both of them

Mongoose update.js

// Model.update
var conditions = { name: 'borne' }
var update = { $inc: { visits: 1 }}
var options = { multi: true }

Model.update(conditions, update, options, callback);

function callback (err, numAffected) {
  // numAffected is the number of updated documents
})

var query = { name: 'borne' }
Model.update(query, { name: 'jason borne' }, options, callback)
// Equals to
Model.update(query, { $set: { name: 'jason borne' }}, options, callback)

Model.findOne({ name: 'borne' }, function (err, doc){
  doc.name = 'jason borne';
  doc.visits.$inc();
  doc.save();
});