Retrieve the document _id by utilizing a callback function

Question

Retrieve the document _id by utilizing a callback function

I'm trying to retrieve the _id of an inserted document in MongoDB using a callback function in nodejs (expressJS), but I'm encountering this error:

AssignmentDB.save is not a function

Below is my code. Can anyone assist me with retrieving the _id using a callback function in MongoDB?

router.route("/assignment/add").post((req, res) => {
  let assignmentDb = new AssignmentDB(req.body);

    AssignmentDB
    .save(assignmentDb, function(err, records){
      if(err) throw err;
      res.status(200).send(records[0]._id); // this should send the _id of the inserted document
    });

});

Here is what my AssignmentDB model looks like:

const mongoose= require('mongoose');
const Schema= mongoose.Schema;

let AssignmentDB = new Schema({
    assignmentName: String,
    assignmentDescription: String,
    courseName: String,
    assignmentDueDate: Date,
    isNewAssignment: Boolean    
});

module.exports = mongoose.model('AssignmentDB', AssignmentDB, 'AssignmentDB');

javascript mongodb express

Answer 1

Answer №1

Modify your router code as shown below:

router.route("/assignment/add").post((req, res) => {
  let assignmentDb = new AssignmentDB(req.body);
    assignmentDb.save(function(err, record){
      if(err) throw err;
      res.status(200).send(record._id); //this should send the inserted document's _id
    });

});

The save method will return the saved record as an object, not an array of objects. Also, remember to call the save method on the Model instance.

Here is a sample example of saving a record in MongoDB:

var mongoose = require('mongoose');

// establish a connection
mongoose.connect('mongodb://localhost:27017/tutorialkart');

// get a reference to the database
var db = mongoose.connection;

db.on('error', console.error.bind(console, 'connection error:'));

db.once('open', function() {
    console.log("Connection Successful!");

    // define the Schema
    var BookSchema = mongoose.Schema({
      name: String,
      price: Number,
      quantity: Number
    });

    // compile the schema to a model
    var Book = mongoose.model('Book', BookSchema, 'bookstore');

    // create a document instance
    var book = new Book({ name: 'Introduction to Mongoose', price: 10, quantity: 25 });

    // save the model to the database
    book.save(function (err, book) {
      if (err) return console.error(err);
      console.log(book + " saved to bookstore.");
    });

});

Answer 2

Modify your router code as shown below:

router.route("/assignment/add").post((req, res) => {
  let assignmentDb = new AssignmentDB(req.body);
    assignmentDb.save(function(err, record){
      if(err) throw err;
      res.status(200).send(record._id); //this should send the inserted document's _id
    });

});

The save method will return the saved record as an object, not an array of objects. Also, remember to call the save method on the Model instance.

Here is a sample example of saving a record in MongoDB:

var mongoose = require('mongoose');

// establish a connection
mongoose.connect('mongodb://localhost:27017/tutorialkart');

// get a reference to the database
var db = mongoose.connection;

db.on('error', console.error.bind(console, 'connection error:'));

db.once('open', function() {
    console.log("Connection Successful!");

    // define the Schema
    var BookSchema = mongoose.Schema({
      name: String,
      price: Number,
      quantity: Number
    });

    // compile the schema to a model
    var Book = mongoose.model('Book', BookSchema, 'bookstore');

    // create a document instance
    var book = new Book({ name: 'Introduction to Mongoose', price: 10, quantity: 25 });

    // save the model to the database
    book.save(function (err, book) {
      if (err) return console.error(err);
      console.log(book + " saved to bookstore.");
    });

});

Retrieve the document _id by utilizing a callback function

Answer №1

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