How to insert a doc into mongodb using mongoose an

问题:

I'm using mongoose to operate mongodb. Now, for testing, I want to inserting some data into mongodb by native connection.

But the question is how to get the generated id after inserting?

I tried:

var mongoose = require('mongoose');

mongoose.connect('mongo://localhost/shuzu_test');

var conn = mongoose.connection;

var user = {
    a: 'abc'
};

conn.collection('aaa').insert(user);

console.log('User:');
console.log(user);

But it prints:

{ a: 'abc' }

There is no _id field.

回答1:

You can generate _id yourself and send it to the database.

var ObjectID = require('mongodb').ObjectID;

var user = {
  a: 'abc',
  _id: new ObjectID()
};

conn.collection('aaa').insert(user);

This is one of my favourite features of MongoDB. If you need to create a number of objects, that are linked to each other, you don't need to make numerous round-trips between app and db. You can generate all ids in the app and then just insert everything.

回答2:

If you use .save then you'll get the _id back in the callback function.

var user = new User({
  a: 'abc'
});

user.save(function (err, results) {
  console.log(results._id);
});

回答3:

You can use the Update method with upsert: true option

aaa.update({
    a : 'abc'
}, {
    a : 'abc'
}, {
    upsert: true
});

回答4:

If you like using Promises:

const collection = conn.collection('aaa');
const instance = new collection({ a: 'abc' });
instance.save()
    .then(result => {
        console.log(result.id);  // this will be the new created ObjectId
    })
    .catch(...)

Or if you're using Node.js >= 7.6.0:

const collection = conn.collection('aaa');
const instance = new collection({ a: 'abc' });
try {
    const result = await instance.save();
    console.log(result.id);  // this will be the new created ObjectId
} catch(...)