Node.js对MongoDB进行增删改查操作的实例代码

const mongoose = require('mongoose');

mongoose.connect('mongodb://localhost/playground')
  .then(() => console.log('Connected to MongoDB...'))
  .catch( err => console.error('Could not connect to MongoDB... ', err));

const courseSchema = new mongoose.Schema({
  name: String,
  author: String,
  tags: [String],
  date: {type: Date, default: Date.now},
  isPublished: Boolean
});

const Course = mongoose.model('Course', courseSchema);
const course = new Course({
  name: 'Nodejs Course',
  author: 'Hiram',
  tags: ['node', 'backend'],
  isPublished: true
});

async function createCourse(){
  const course = new Course({
    name: 'Nodejs Course',
    author: 'Hiram',
    tags: ['node', 'backend'],
    isPublished: true
  });
  
  const result = await course.save();
  console.log(result);
}

createCourse();

async function getCourses(){
  const courses = await Course
    .find({author: 'Hiram', isPublished: true})
    .limit(10)
    .sort({name: 1})
    .select({name: 1, tags:1});
  console.log(courses);
}
getCourses();

async function getCourses(){
  const courses = await Course
    // .find({author: 'Hiram', isPublished: true})
    // .find({ price: {$gt: 10, $lte: 20} })
    .find({price: {$in: [10, 15, 20]} })
    .limit(10)
    .sort({name: 1})
    .select({name: 1, tags:1});
  console.log(courses);
}
getCourses();

async function getCourses(){
  const courses = await Course
    // .find({author: 'Hiram', isPublished: true})
    .find()
    // .or([{author: 'Hiram'}, {isPublished: true}])
    .and([{author: 'Hiram', isPublished: true}])
    .limit(10)
    .sort({name: 1})
    .select({name: 1, tags:1});
  console.log(courses);
}
getCourses();

async function getCourses(){
  const courses = await Course
    // .find({author: 'Hiram', isPublished: true})
    //author字段以“Hiram”开头
    // .find({author: /^Hiram/})
    //author字段以“Pierce”结尾
    // .find({author: /Pierce$/i })
    //author字段包含“Hiram”
    .find({author: /.*Hiram.*/i })
    .limit(10)
    .sort({name: 1})
    .select({name: 1, tags:1});
  console.log(courses);
}
getCourses();

async function getCourses(){
  const courses = await Course
    .find({author: 'Hiram', isPublished: true})
    .count();
  console.log(courses);
}
getCourses();

async function getCourses(){
  const pageNumber = 2;
  const pageSize = 10;
  const courses = await Course
    .find({author: 'Hiram', isPublished: true})
    .skip((pageNumber - 1) * pageSize)
    .limit(pageSize)
    .sort({name: 1})
    .select({name: 1, tags: 1});
  console.log(courses);
}
getCourses();

async function updateCourse(id){
  const course = await Course.findById(id);
  if(!course) return;
  course.isPublished = true;
  course.author = 'Another Author';
  const result = await course.save();
  console.log(result);
}

async function updateCourse(id){
  const course = await Course.findByIdAndUpdate(id, {
    $set: {
      author: 'Jack',
      isPublished: false
    }
  }, {new: true}); //true返回修改后的文档，false返回修改前的文档
  console.log(course);
}

async function removeCourse(id){
  // const result = await Course.deleteMany({ _id: id});
  const course = await Course.findByIdAndRemove(id);
  console.log(course)
}