Mongoose 验证：必需：错误，验证：正则表达式，空值问题

Mongoose 验证：必需：错误，验证：正则表达式，空值问题

javascript
const mongoose = require('mongoose');
const UserSchema = new mongoose.Schema({
  username: {
    type: String,
    required: true
  },
  email: {
    type: String,
    required: true
  }
});
const User = mongoose.model('User', UserSchema);
const user = new User({
  username: 'JohnDoe',
  email: 'johndoe@example.com'
});
user.save((err) => {
  if (err) {
    console.error(err);
  } else {
    console.log('User saved successfully');
  }
});

javascript
const mongoose = require('mongoose');
const ProductSchema = new mongoose.Schema({
  name: {
    type: String,
    required: true
  },
  price: {
    type: Number,
    required: true
  },
  SKU: {
    type: String,
    validate: {
      validator: function(value) {
        return /^SKU-\d{6}$/.test(value);
      },
      message: 'SKU must be in the format of SKU-000000'
    }
  }
});
const Product = mongoose.model('Product', ProductSchema);
const product = new Product({
  name: 'Product 1',
  price: 9.99,
  SKU: 'SKU-123456'
});
product.save((err) => {
  if (err) {
    console.error(err);
  } else {
    console.log('Product saved successfully');
  }
});

javascript
const mongoose = require('mongoose');
const OrderSchema = new mongoose.Schema({
  orderNumber: {
    type: String,
    required: true
  },
  totalPrice: {
    type: Number,
    required: true,
    validate: {
      validator: function(value) {
        return value !== null;
      },
      message: 'Total price cannot be null'
    }
  }
});
const Order = mongoose.model('Order', OrderSchema);
const order1 = new Order({
  orderNumber: '123456',
  totalPrice: null
});
const order2 = new Order({
  orderNumber: '789012',
  totalPrice: 19.99
});
order1.save((err) => {
  if (err) {
    console.error(err);
  } else {
    console.log('Order 1 saved successfully');
  }
});
order2.save((err) => {
  if (err) {
    console.error(err);
  } else {
    console.log('Order 2 saved successfully');
  }
});