Going over some basic Sequelize/Express stuff

miladsDb.js

//npm i body-parser express pg pg-hstore sequelize
//postgres - RDBMS - our database server for handeling SQL over TCP/IP
//PG - our connection between postgress and PG
//Sequelize - our ORM that behind the scenes uses pg but gives us the power of javascript objects to use our database with properties and methods
const express = require('express');
//Create instance of express
const app = express();
//To help us turn the body from a request into a JS object
const bodyParser = require('body-parser');
const sequelize = require('sequelize');
const Port = 8080;

//db is our connection to the postgres server and it's database
const db = new sequelize('postgres://localhost:5432/miladsDB');

//db.define is how we create a new table Model.  The first argument is it's name, the second is definining it's properties, and the third is an object that defines methods we can use on the model or instance
const Student = db.define('student', {
  name: {
    type: sequelize.TEXT,
    allowNull: false
  },
  age: {
    type: sequelize.INTEGER,
    allowNull: false
  },
  city: {
    type: sequelize.STRING,
    allowNull: false
  }
},
  {
  hooks: {
    beforeValidate: function (student) {
      //runs before validation so that if there isn't this property set when we go to .create(), it will make it for us.
      if (!student.age) {
        student.age = 25;
      }
    }
  },
  getterMethods: {
    awesomeAge: function () {
      //this is used like let awesomeAge = student.awesomeAge.  this referes to the instance
      return `Awesome you are ${this.age}`
    }
  },
  classMethods: {
    //Methods on the Model itself.  Student.findByCity('Dallas');
    findByCity: function (city) {
      return Student.findAll({
        where: {
          city: city
        }
      })
    }
  },
  instanceMethods: {
    findSimilar: function () {
      //Methods on an instance of a model.  student.findSimilar()
      return Student.findAll({
        where: {
          age: {
            age: this.age
          },
          id: {
            $ne: this.id
          }
        }
      })
    }
  }
})

//Setting up our middleware for express to parse the body
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({extended: false}));


//Route to find all the Students.  Array returned even if it's just one item.
app.get('/students', (req,res,next)=>{
  Student.findAll({})
    .then((students) => {
      res.send(students)
    })
    .catch(next);
})

//route to find just one instance of student.
app.get('/students/:id', (req,res,next)=>{
  let id = req.params.id;
  Student.findById(id)
    .then((student) => {
      res.send(student);
    })
})


//Syncing our model to make sure this table exists on the database
//
Student.sync({force: true})
  .then(()=>{
    app.listen(Port, ()=>{
      console.log(`Listening on ${Port}`)
    });
  })
  .catch(console.error);