Sequelize Tutorial:

This is a simple nodejs server setup to checkout Sequelize ORM for mysql.

Steps by Step Guide:

1. npm install --save mysql2 sequelize express body-parser chalk

   • mysql2 : is the mysql client library needed here.
   • body-parser: parse request body.
   • express : to easly create and manage a node server.
   • chalk : used to bring some colors on the console logs.

2. Create a simple server with express.

   • create file server.js and setup a simple server on the file.
   • create a simple libraries.js file to act as the central file to import any external_module
   • create an empty database.js file.

3. npm install -g sequelize-cli

   • This is the command line interface for creating ORM for database.

4. sequelize init

   • command initializes directory with folders like seeders, models, config & migrations.
   • config: contains configurations for every enviroment type.
   • models: where we can create any table schemas.
   • migrations : contains table schema for table creation and table deletions.

5. delete the default index.js file in /models.

   • we will be building connection varibles from scratch.
   • create file Tweets.js.

6. on database.js create an instance of Sequelize with configuations from config/config.js

   • export the created instance.
   • Import this instace at Tweets.js to define the schema for tweets.

7. sequelize migration:create --name create_table_tweets

   • creates a migration file in /migration folder.
   • Edit up method to create database with same schema model as in Tweets.js.
   • Add columns createdAt & updatedAt at migration. These fields are automatically updated by sequelize on creat an update operations.
   • Edit down method to drop and delete table.
   • sequelize db:migrate command to create the table and reflect the changes in database.

8. Also create the Users.js file and migrations for Users.

9. sequelize db:migrate:undo : undo just last migration.

10. sequelize db:migrate:undo all : undo all migrations.

11. Creates /routes folder.

    • Create route GET / for handling default requests.
    • Create route POST /createUser for creating user.
    • Create route POST /createTweet for creating tweet.
    • Create route POST /getAllTweets for fetching all tweets.
    • Create route POSt /getTweetsById for fetching tweet of a particular user.

12. /createUser:

    • User.create({username: "value1", password: "value2"}) to create user.

13. /createTweet:

    • Tweets.create({content: "value1", userId: 1}) to create tweet.

14. /getAllTweets:

    • Tweets.findAll({offset: 0, limit: 10}) to fetch all tweets avalible.
    • offset and limit keys could be used for paginated fetching.

15. /getTweetsById:

    • Tweets.findAll({offset:0, limit:10, where: {userId: 1}}) to fetch tweets by the user of userId = 1

Sample Curl Requests:

1. curl -X POST -H "Content-Type: application/json" -d '{"username":"jake", "password":"12345"}' http://localhost:4200/createUser

   Response :

   {"message":"User Created Successfully","data":{"id":1,"username":"jake","password":"12345","updatedAt":"2019-10-24T21:04:03.179Z","createdAt":"2019-10-24T21:04:03.179Z"},"error":false}

2. curl -X POST -H "Content-Type: application/json" -d '{"content":"This is my first test tweet", "userId": 1}' http://localhost:4200/createTweet

   Response :

   {"message":"Tweet Created Successfully","data":{"id":1,"content":"This is my first test tweet","userId":1,"updatedAt":"2019-10-24T21:06:01.227Z","createdAt":"2019-10-24T21:06:01.227Z"},"error":false}

3. curl -X POST -H "Content-Type: application/json" -d '{"offset":2, "limit":5}' http://localhost:4200/getAllTweets

   Response :

   {"message":"Tweets Fetched Successfully","data":[{"id":3,"content":"This is the third successive tweet to insert.","userId":1,"createdAt":"2019-10-24T21:06:53.000Z","updatedAt":"2019-10-24T21:06:53.000Z"}],"error":false}

4. curl -X POST -H "Content-Type: application/json" -d '{"offset":0, "limit":5, "userId":2}' http://localhost:4200/getTweetsById

   Response :

   {"message":"Tweets Fetched Successfully","data":[{"id":4,"content":"This is the first tweet by misty.","userId":2,"createdAt":"2019-10-24T21:10:53.000Z","updatedAt":"2019-10-24T21:10:53.000Z"}],"error":false}

How to Use:

* clone respository.
* create database in mysql.
* npm install && npm start.
* checkout provided curl commands.