mongo-crud-shema-snippet.js

const mongoose = require("mongoose");

mongoose.connect("mongodb://localhost/playground", { useNewUrlParser: true })
  .then(() => console.log("Mongo db is connected!"))
  .catch((err) => console.error("Could not connect to db ...", err));

const courseSchema = new mongoose.Schema({
  name: { type: String, required: true },
  author: { type: String, required: true, minlength: 3, maxlength: 255 },
  category: {
    type: String,
    required: true,
    enum: ['web', 'mobile', 'networking'], // predefined
    lowercase: true, // turns the value to lowercase b4 save
    trim: true
  },
  // tags: [String], // array of string, for validation required: true will not work since empty array is a value
  tags : {
    type: Array,
    validate: {
      validator: function(v){
        return v && v.length > 0; // check v exists if client return tags as null
      },
      message: "You must give a tag for a course"
    }
  },
  date: { type: Date, default: Date.now },
  isPublished: Boolean,
  price: {
    type: Number,
    // if course is published, then price is required
    required: function() { return this.isPublished; },
    min: 10,
    max: 20,
    // get: v => Math.round(v), // we can also user getter/setter
    // set: v => Math.round(v)
  },

  // for model relationship
  // author: {
  //   type: mongoose.Schema.Types.ObjectId,
  //   ref: "Author"
  // }
});

const Course = mongoose.model("Course", courseSchema);

async function createCourse(){
  let course = new Course({
    name: "Vue js Course",
    author: "John Doe",
    category: "web",
    tags: ['vue', 'js'],
    isPublished: true,
    price: 14.40
  });  

  try{
    let result = await course.save();
    console.log(result);
  }
  catch(ex){
    console.log(ex.message);
    for (let field in ex.errors)
      console.log(ex.errors[field].message)
  }

}

// createCourse();

async function getCourses(){
  // eq (equal)
  // ne (not equal)
  // gt (greater than)
  // gte (greater than or equal to)
  // lt (less than)
  // lte (less than or equal to)
  // in
  // nin (not in)

  // for pagination
  // let pageNumber = 2;
  // let pageSize = 10;

  let courses = await Course.find({ author: 'John Doe', isPublished: true})
     // .find({price: { $lte: 10, $gte: 20 }})
     // .find({ price: { $in: [10, 20, 30] }})
     // .find().or([ { author: "John" }, { isPublished: true }])
     // .find().and([ { author: "John" }, { isPublished: true }])
     // .find({ author: /pattern/ }) // regular expression
    .sort({ name: 1 })
    .select({ name: 1, tags: 1  })
    .limit(10);
    // .count()
    // .skip((pageNumber - 1) * pageSize)
    // .limit(pageSize)
  console.log(courses);
}

getCourses();

async function updateCourse(id){
  let course = await Course.findById(id);
  if(!course) return;

  course.name = "Angular Course";

  // another approach
  // course.set({
  //   name: "Angular Course"
  // })

  //let result = await course.save();
  console.log(course);
}

// updateCourse('5bbd780ddd48394cc7328eb5');

async function deleteCourse(id){
  let course = await Course.deleteOne({_id: id});
  console.log(course);
}

//deleteCourse('5bbd780ddd48394cc7328eb5');


// router.post('/', async (req, res) => {
//   let course = new Course({
//     // req.body
//   });

//   let result = await course.save();

//   return res.status(201).send(result);

// })