Mongoose 中的虚拟与方法

Mongoose是一个非常流行的Node.js库，用于在MongoDB中建模和操作数据。其中有两个非常有用的功能是虚拟（Virtual）和方法（Method）。虚拟是一个在Mongoose模型中定义的计算属性，它不会被存储在数据库中，但可以通过模型的实例访问。方法是在模型实例上定义的函数，可以执行一些特定的操作。在本文中，我们将详细介绍Mongoose中的虚拟和方法，并提供一些实际的案例代码。

javascript
const mongoose = require('mongoose');
const userSchema = new mongoose.Schema({
  firstName: String,
  lastName: String
});
userSchema.virtual('fullName').get(function() {
  return this.firstName + ' ' + this.lastName;
});
const User = mongoose.model('User', userSchema);
const user = new User({
  firstName: 'John',
  lastName: 'Doe'
});
console.log(user.fullName); // 输出 "John Doe"

javascript
const mongoose = require('mongoose');
const userSchema = new mongoose.Schema({
  firstName: String,
  lastName: String
});
userSchema.methods.getFullName = function() {
  return this.firstName + ' ' + this.lastName;
};
const User = mongoose.model('User', userSchema);
const user = new User({
  firstName: 'John',
  lastName: 'Doe'
});
console.log(user.getFullName()); // 输出 "John Doe"

javascript
userSchema.virtual('age').get(function() {
  const birthYear = new Date(this.dateOfBirth).getFullYear();
  const currentYear = new Date().getFullYear();
  return currentYear - birthYear;
});

javascript
userSchema.methods.encryptPassword = async function() {
  this.password = await bcrypt.hash(this.password, saltRounds);
};
const user = new User({
  username: 'john_doe',
  password: 'password123'
});
await user.encryptPassword();
await user.save();