Example 1: mongoose populate
Story.
findOne({ title: /casino royale/i }).
populate('author', 'name'). // only return the Persons name
exec(function (err, story) {
if (err) return handleError(err);
console.log('The author is %s', story.author.name);
// prints "The author is Ian Fleming"
console.log('The authors age is %s', story.author.age);
// prints "The authors age is null'
});
Example 2: mongodb populate document
Story.
findOne({ title: 'Casino Royale' }).
populate('author').
exec(function (err, story) {
if (err) return handleError(err);
console.log('The author is %s', story.author.name);
// prints "The author is Ian Fleming"
});
Example 3: mongoos populate a ref
const storySchema = Schema({
authors: [{ type: Schema.Types.ObjectId, ref: 'Person' }],
title: String
});
// Later
const story = await Story.findOne({ title: 'Casino Royale' }).populate('authors');
story.authors; // `[]`
Example 4: mongoose populate()
// populates a single object
User.findById(id, function (err, user) {
const 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) {
const opts = [{ path: 'company', match: { x: 1 }, select: 'name' }];
const 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' }
// and this schema:
// new Schema({
// name: String,
// weapon: { type: ObjectId, ref: 'Weapon' }
// });
const 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
const 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
// it is in the schema's ref
Example 5: how to use mongoose populate
function getUserWithPosts(username){ return User.findOne({ username: username }) .populate('posts').exec((err, posts) => { console.log("Populated User " + posts); })}
Example 6: how to use mongoose populate
{ _id: 59ab1c92ea84486fb4ba9f28, username: JD, posts: [ "59ab1b43ea84486fb4ba9ef0", "59ab1b43ea84486fb4ba9ef1" ]}