What are the common CRUD operation methods in Mongoose Model?

Mongoose Model is a constructor compiled from Schema, used to create and manipulate MongoDB documents. Model instances represent documents in the database and provide rich CRUD operation methods.

Creating Model

javascript
const mongoose = require('mongoose');
const userSchema = new mongoose.Schema({
  name: String,
  email: String,
  age: Number
});

// Create Model, first parameter is collection name (automatically converted to plural)
const User = mongoose.model('User', userSchema);

Main Model Methods

Creating Documents

javascript
// Method 1: Using new keyword
const user = new User({ name: 'John', email: 'john@example.com' });
await user.save();

// Method 2: Using create method
const user = await User.create({ name: 'John', email: 'john@example.com' });

// Method 3: Using insertMany
const users = await User.insertMany([
  { name: 'John', email: 'john@example.com' },
  { name: 'Jane', email: 'jane@example.com' }
]);

Querying Documents

javascript
// Find all
const users = await User.find();

// Conditional query
const user = await User.findOne({ email: 'john@example.com' });
const users = await User.find({ age: { $gte: 18 } });

// Find by ID
const user = await User.findById('507f1f77bcf86cd799439011');

// Chained query
const users = await User.find({ age: { $gte: 18 } })
  .select('name email')
  .sort({ name: 1 })
  .limit(10);

Updating Documents

javascript
// Update single document
const user = await User.findByIdAndUpdate(
  '507f1f77bcf86cd799439011',
  { age: 25 },
  { new: true } // Return updated document
);

// Conditional update
const result = await User.updateOne(
  { email: 'john@example.com' },
  { age: 25 }
);

// Batch update
const result = await User.updateMany(
  { age: { $lt: 18 } },
  { status: 'minor' }
);

// findOneAndUpdate
const user = await User.findOneAndUpdate(
  { email: 'john@example.com' },
  { age: 25 },
  { new: true }
);

Deleting Documents

javascript
// Delete by ID
const user = await User.findByIdAndDelete('507f1f77bcf86cd799439011');

// Conditional delete
const result = await User.deleteOne({ email: 'john@example.com' });

// Batch delete
const result = await User.deleteMany({ age: { $lt: 18 } });

// findOneAndDelete
const user = await User.findOneAndDelete({ email: 'john@example.com' });

Counting Documents

javascript
const count = await User.countDocuments({ age: { $gte: 18 } });
const count = await User.estimatedDocumentCount(); // Fast estimation

Model Static Methods

You can add custom static methods to Schema:

javascript
userSchema.statics.findByEmail = function(email) {
  return this.findOne({ email });
};

const User = mongoose.model('User', userSchema);
const user = await User.findByEmail('john@example.com');