node.js - How to get the objectID after I save an object in Mongoose?

Node.js - How to get the objectID after I save an object in Mongoose?

In Mongoose, when you save a new document, you can obtain its _id (which is an ObjectId) either synchronously or asynchronously, depending on your preference and the context of your application. Here's how you can achieve this:

Asynchronous Approach (Recommended)

Using Mongoose's save() method asynchronously allows you to handle the result and get the _id once the document has been successfully saved:

const mongoose = require('mongoose'); const Schema = mongoose.Schema; // Define a schema const yourSchema = new Schema({ // Define your schema fields here name: String, age: Number }); // Create a model const YourModel = mongoose.model('YourModel', yourSchema); // Create a new document const newObj = new YourModel({ name: 'John Doe', age: 30 }); // Save the document newObj.save() .then(savedObj => { console.log('Saved object:', savedObj); console.log('Object ID:', savedObj._id); // Access the saved object's _id }) .catch(error => { console.error('Error saving object:', error); });

Synchronous Approach (Not Recommended in Node.js)

In Node.js applications, synchronous operations can block the event loop and are generally discouraged, especially for database operations. However, for completeness, here's how you would do it synchronously in Mongoose:

const mongoose = require('mongoose'); const Schema = mongoose.Schema; // Define a schema const yourSchema = new Schema({ // Define your schema fields here name: String, age: Number }); // Create a model const YourModel = mongoose.model('YourModel', yourSchema); // Create a new document const newObj = new YourModel({ name: 'John Doe', age: 30 }); // Save the document synchronously try { const savedObj = await newObj.save(); console.log('Saved object:', savedObj); console.log('Object ID:', savedObj._id); // Access the saved object's _id } catch (error) { console.error('Error saving object:', error); }

Notes:

  • Asynchronous Approach: This is generally preferred in Node.js applications because it allows other operations to proceed while waiting for the save operation to complete.
  • Error Handling: Always handle errors properly using .catch() in promises or try-catch blocks in asynchronous functions.
  • Object ID Access: The _id of the saved document is available directly on the object returned by save() or in the .then() callback of the promise.
  • Mongoose Models: Ensure your Mongoose model and schema (YourModel and yourSchema in the examples) are defined correctly with all necessary fields and validations.

By following these examples, you can effectively retrieve the ObjectId of a saved document in Mongoose, ensuring smooth handling of asynchronous operations in your Node.js application.

Examples

  1. Node.js retrieve objectID after saving with Mongoose save() method:

    • Description: After saving an object with Mongoose, retrieve the generated objectID.
    • Code:
      const mongoose = require('mongoose'); const Schema = mongoose.Schema; // Define a schema const userSchema = new Schema({ name: String, email: String }); // Create a model const User = mongoose.model('User', userSchema); // Create a new user instance const newUser = new User({ name: 'John Doe', email: 'john@example.com' }); // Save the user newUser.save() .then(savedUser => { console.log('Saved user with ID:', savedUser._id); }) .catch(err => { console.error('Error saving user:', err); });

  2. Node.js get objectID using insertedId after saving with Mongoose:

    • Description: Access the insertedId property from the result object after saving with Mongoose.
    • Code:
      const mongoose = require('mongoose'); const Schema = mongoose.Schema; // Define a schema const userSchema = new Schema({ name: String, email: String }); // Create a model const User = mongoose.model('User', userSchema); // Create a new user instance const newUser = new User({ name: 'Jane Doe', email: 'jane@example.com' }); // Save the user newUser.save() .then(result => { console.log('Saved user with ID:', result.insertedId); }) .catch(err => { console.error('Error saving user:', err); });

  3. Node.js retrieve objectID using ._id after Mongoose save operation:

    • Description: Access the _id property directly from the saved document object.
    • Code:
      const mongoose = require('mongoose'); const Schema = mongoose.Schema; // Define a schema const productSchema = new Schema({ name: String, price: Number }); // Create a model const Product = mongoose.model('Product', productSchema); // Create a new product instance const newProduct = new Product({ name: 'Laptop', price: 1200 }); // Save the product newProduct.save() .then(savedProduct => { console.log('Saved product with ID:', savedProduct._id); }) .catch(err => { console.error('Error saving product:', err); });

  4. Node.js get objectID using doc._id after Mongoose save operation:

    • Description: Retrieve the _id property from the saved document using the doc object.
    • Code:
      const mongoose = require('mongoose'); const Schema = mongoose.Schema; // Define a schema const orderSchema = new Schema({ orderId: String, totalAmount: Number }); // Create a model const Order = mongoose.model('Order', orderSchema); // Create a new order instance const newOrder = new Order({ orderId: 'ORD001', totalAmount: 500 }); // Save the order newOrder.save() .then(doc => { console.log('Saved order with ID:', doc._id); }) .catch(err => { console.error('Error saving order:', err); });

  5. Node.js access objectID using .id getter after Mongoose save operation:

    • Description: Use the .id getter to access the _id property after saving the document.
    • Code:
      const mongoose = require('mongoose'); const Schema = mongoose.Schema; // Define a schema const bookSchema = new Schema({ title: String, author: String }); // Create a model const Book = mongoose.model('Book', bookSchema); // Create a new book instance const newBook = new Book({ title: 'Node.js Basics', author: 'John Smith' }); // Save the book newBook.save() .then(savedBook => { console.log('Saved book with ID:', savedBook.id); }) .catch(err => { console.error('Error saving book:', err); });

  6. Node.js retrieve objectID using .save() callback with doc._id:

    • Description: Access the _id property in the callback function after saving the document.
    • Code:
      const mongoose = require('mongoose'); const Schema = mongoose.Schema; // Define a schema const taskSchema = new Schema({ taskName: String, completed: Boolean }); // Create a model const Task = mongoose.model('Task', taskSchema); // Create a new task instance const newTask = new Task({ taskName: 'Complete project', completed: false }); // Save the task newTask.save((err, doc) => { if (err) { console.error('Error saving task:', err); } else { console.log('Saved task with ID:', doc._id); } });

  7. Node.js get objectID using .save() callback with .id getter:

    • Description: Retrieve the _id property using the .id getter in the save callback.
    • Code:
      const mongoose = require('mongoose'); const Schema = mongoose.Schema; // Define a schema const commentSchema = new Schema({ content: String, author: String }); // Create a model const Comment = mongoose.model('Comment', commentSchema); // Create a new comment instance const newComment = new Comment({ content: 'Great article!', author: 'Anonymous' }); // Save the comment newComment.save((err, savedComment) => { if (err) { console.error('Error saving comment:', err); } else { console.log('Saved comment with ID:', savedComment.id); } });

  8. Node.js access objectID using .then() with result._id after Mongoose save():

    • Description: Access the _id property using result._id in the then() block after saving.
    • Code:
      const mongoose = require('mongoose'); const Schema = mongoose.Schema; // Define a schema const eventSchema = new Schema({ eventName: String, date: Date }); // Create a model const Event = mongoose.model('Event', eventSchema); // Create a new event instance const newEvent = new Event({ eventName: 'Birthday Party', date: new Date('2024-07-15') }); // Save the event newEvent.save() .then(result => { console.log('Saved event with ID:', result._id); }) .catch(err => { console.error('Error saving event:', err); });

  9. Node.js retrieve objectID using .then() with .id getter after Mongoose save():

    • Description: Retrieve the _id property using the .id getter in the then() block after saving.
    • Code:
      const mongoose = require('mongoose'); const Schema = mongoose.Schema; // Define a schema const taskSchema = new Schema({ taskName: String, completed: Boolean }); // Create a model const Task = mongoose.model('Task', taskSchema); // Create a new task instance const newTask = new Task({ taskName: 'Finish report', completed: false }); // Save the task newTask.save() .then(savedTask => { console.log('Saved task with ID:', savedTask.id); }) .catch(err => { console.error('Error saving task:', err); });

  10. Node.js access objectID using async/await with savedDoc._id after Mongoose save():

    • Description: Use async/await syntax to retrieve the _id property after saving with Mongoose.
    • Code:
      const mongoose = require('mongoose'); const Schema = mongoose.Schema; // Define a schema const noteSchema = new Schema({ content: String, createdBy: String }); // Create a model const Note = mongoose.model('Note', noteSchema); async function saveNote() { try { const newNote = new Note({ content: 'Reminder', createdBy: 'Admin' }); const savedNote = await newNote.save(); console.log('Saved note with ID:', savedNote._id); } catch (err) { console.error('Error saving note:', err); } } saveNote();

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