02 - Initialize

In this module, we will use Sequelize to connect our server to PG Admin.

Orientation

Right now we'll be working with Sequelize and Postgres:

screenshot

Sequelize Connection

To use Sequelize, we'll have to establish a connection. This is the standard approach from the docs, and it is often copy and pasted into projects for setup. Simply put, it's allowing us to connect from our project to the Postgres database. If you haven't already done so, create the file db.js inside your server folder and put this code inside of it:

//1
const Sequelize = require('sequelize');

      //2               //3       //4         //5            //6          
const sequelize = new Sequelize('workoutlog', 'postgres', 'Letmein1234!', {
    host: 'localhost', //7
    dialect: 'postgres'  ///8
});
    //9      //10         //11         
sequelize.authenticate().then(
    function() { //12
        console.log('Connected to workoutlog postgres database');
    },
    function(err){ //13
        console.log(err);
    }
);
                 //14
module.exports = sequelize;

Analysis

Let's do some analysis of the code above. You do not need to memorize all of this information. Read through it, and then use it as a reference for when you need it next:

Concept	Analysis
1	Import the Sequelize package.
2	Create an instance of Sequelize for use in the module with the sequelize variable.
3	Use the constructor to create a new Sequelize object.
4	Identify the db table to connect to.
5	The username for the db.
6	The password for the local db.
7	The host points to the local port for Sequelize. This is 5432.
8	Identify the QL dialect being used. Could be MSSQL, SQLLite, or others
9	Use the sequelize variable to access methods.
10	Call the authenticate() method.
11	authenticate() returns a promise. Use .then().
12	Fire a function that shows if we're connected.
13	Fire an error if there are any errors.
14	Export the module.

app.js

We also need to do some configuration in our app.js file.

Do the following: 1. Create a sequelize variable that imports the db file. 2. Use the variable and call .sync(). This method will ensure that we sync all defined models to the DB.

var express = require('express');
var app = express();
var test= require('./controllers/testcontroller')
//1
var sequelize = require('./db');

//2
sequelize.sync(); // tip: pass in {force: true} for resetting tables

app.use('/test', test)

NOTE: When you run your database with Sequelize, you may see the following message:

depreciated Strings

Newer versions of sequelize make use of the new Symbol datatype instead of relying on strings. You can still use strings for now; this message just means that in the future they may not. We haven't covered Symbols much, but feel free to do some research on your own and try them out.