mongoose populate

1const storySchema = Schema({
2  authors: [{ type: Schema.Types.ObjectId, ref: 'Person' }],
3  title: String
4});
5
6// Later
7
8const story = await Story.findOne({ title: 'Casino Royale' }).populate('authors');
9story.authors; // `[]`

1// populates a single object
2User.findById(id, function (err, user) {
3  const opts = [
4    { path: 'company', match: { x: 1 }, select: 'name' },
5    { path: 'notes', options: { limit: 10 }, model: 'override' }
6  ];
7
8  User.populate(user, opts, function (err, user) {
9    console.log(user);
10  });
11});
12
13// populates an array of objects
14User.find(match, function (err, users) {
15  const opts = [{ path: 'company', match: { x: 1 }, select: 'name' }];
16
17  const promise = User.populate(users, opts);
18  promise.then(console.log).end();
19})
20
21// imagine a Weapon model exists with two saved documents:
22//   { _id: 389, name: 'whip' }
23//   { _id: 8921, name: 'boomerang' }
24// and this schema:
25// new Schema({
26//   name: String,
27//   weapon: { type: ObjectId, ref: 'Weapon' }
28// });
29
30const user = { name: 'Indiana Jones', weapon: 389 };
31Weapon.populate(user, { path: 'weapon', model: 'Weapon' }, function (err, user) {
32  console.log(user.weapon.name); // whip
33})
34
35// populate many plain objects
36const users = [{ name: 'Indiana Jones', weapon: 389 }]
37users.push({ name: 'Batman', weapon: 8921 })
38Weapon.populate(users, { path: 'weapon' }, function (err, users) {
39  users.forEach(function (user) {
40    console.log('%s uses a %s', users.name, user.weapon.name)
41    // Indiana Jones uses a whip
42    // Batman uses a boomerang
43  });
44});
45// Note that we didn't need to specify the Weapon model because
46// it is in the schema's ref

1{  _id: 59ab1c92ea84486fb4ba9f28,  username: JD,  posts: [    "59ab1b43ea84486fb4ba9ef0",    "59ab1b43ea84486fb4ba9ef1"  ]}

1// The 2nd `populate()` call below overwrites the first because they
2// both populate 'fans'.
3Story.
4  find().
5  populate({ path: 'fans', select: 'name' }).
6  populate({ path: 'fans', select: 'email' });
7// The above is equivalent to:
8Story.find().populate({ path: 'fans', select: 'email' });

1//EXAMPLE TWO
2
3const mongoose = require('mongoose')
4const shortid = require('shortid')
5
6/**
7 * @description setup database connection
8 */
9mongoose
10  .connect('mongodb://localhost:27017/mongoose', {
11    useFindAndModify: false,
12    useUnifiedTopology: true,
13    useNewUrlParser: true
14  })
15  .then(() => console.log('Connected'))
16  .catch(() => console.log('Not Connected'))
17
18/**
19 * @description course mongoose schema
20 */
21
22const CourseSchema = new mongoose.Schema(
23  {
24    userId: { type: mongoose.Types.ObjectId },
25    course: []
26  },
27  { timestamps: true }
28)
29
30const Course = mongoose.model('Course', CourseSchema, 'Course')
31
32/**
33 * @description user mongoose schema
34 */
35
36const UserSchema = new mongoose.Schema(
37  {
38    fullName: {
39      type: String,
40      trim: true,
41      required: true
42    },
43    courseId: {
44      type: String,
45      ref: 'Course',
46      default: shortid.generate
47    }
48  },
49  { timestamps: true }
50)
51
52UserSchema.post('save', async function (doc, next) {
53  if (doc) {
54    await Course.create({ userId: doc._id })
55    next()
56  }
57})
58
59const User = mongoose.model('User', UserSchema, 'User')
60
61/**
62 * @description register user account
63 */
64
65async function registerAccount() {
66  const userData = new User({ fullName: 'john doe' })
67  await userData.save()
68
69  console.log('register successfuly')
70  process.exit(0)
71}
72registerAccount()
73
74/**
75 * @description buy video course
76 */
77
78async function buyCourse() {
79  const user = await User.findOne({ fullName: 'john doe' })
80
81  const course = await Course.updateOne(
82    { userId: user._id },
83    {
84      $push: {
85        course: {
86          $each: [
87            { name: 'react for beginner', price: 95000 },
88            { name: 'vue for beginner', price: 85000 },
89            { name: 'angular for beginner', price: 75000 }
90          ]
91        }
92      }
93    }
94  )
95
96  console.log('sucessfuly to buy course')
97  process.exit(0)
98}
99// buyCourse()
100
101/**
102 * @description results all course after buy course
103 */
104
105async function resultsCourse() {
106  const user = await User.findOne({ fullName: 'john doe' })
107
108  const courseResult = await Course.findOne({ userId: user._id })
109    .populate({
110      path: 'userId',
111      select: 'course firstName lastName'
112    })
113    .lean()
114
115  console.log({
116    fullname: user.fullName,
117    courses: courseResult.course
118  })
119  process.exit(0)
120}
121// resultsCourse()
122

1//EXAMPLE ONE
2
3const mongoose = require('mongoose')
4const shortid = require('shortid')
5
6/**
7 * @description setup database connection
8 */
9
10mongoose
11  .connect('mongodb://localhost:27017/mongoose', {
12    useFindAndModify: false,
13    useUnifiedTopology: true,
14    useNewUrlParser: true
15  })
16  .then(() => console.log('Connected'))
17  .catch(() => console.log('Not Connected'))
18
19/**
20 * @description user mongoose schema
21 */
22
23const UserSchema = new mongoose.Schema(
24  {
25    fullName: {
26      type: String,
27      trim: true,
28      required: true
29    },
30    courseId: {
31      type: String,
32      ref: 'Course',
33      default: shortid.generate
34    }
35  },
36  { timestamps: true }
37)
38
39const User = mongoose.model('User', UserSchema, 'User')
40
41/**
42 * @description course mongoose schema
43 */
44
45const CourseSchema = new mongoose.Schema(
46  {
47    userId: { type: mongoose.Types.ObjectId },
48    course: []
49  },
50  { timestamps: true }
51)
52
53const Course = mongoose.model('Course', CourseSchema)
54
55/**
56 * @description register user account
57 */
58
59async function registerAccount() {
60  const user = await User.create({ fullName: 'john doe' })
61
62  await Course.create({ userId: user._id })
63
64  console.log('register successfuly')
65  process.exit(0)
66}
67//registerAccount
68
69/**
70 * @description buy video course
71 */
72
73async function buyCourse() {
74  const user = await User.findOne({ fullName: 'john doe' })
75
76  const course = await Course.updateOne(
77    { userId: user._id },
78    {
79      $push: {
80        course: {
81          $each: [
82            { name: 'react for beginner', price: 95000 },
83            { name: 'vue for beginner', price: 85000 },
84            { name: 'angular for beginner', price: 75000 }
85          ]
86        }
87      }
88    }
89  )
90
91  console.log('sucessfuly to buy course')
92  process.exit(0)
93}
94// buyCourse()
95
96/**
97 * @description results all course after buy course
98 */
99
100async function resultsCourse() {
101  const user = await User.findOne({ fullName: 'john doe' })
102
103  const courseResult = await Course.findOne({ userId: user._id })
104    .populate({
105      path: 'userId',
106      select: 'course firstName lastName'
107    })
108    .lean()
109
110  console.log({
111    fullname: user.fullName,
112    courses: courseResult.course
113  })
114  process.exit(0)
115}
116resultsCourse()
117