Introduction to sequelise / node and other js stuff.

notes.md

Sequelize - basic notes.

This note contains some remarks on my first (and painful) attempt to switch from ruby+postgres to javascript+postgres.

// thanks to Marcus & Ben for the introduction.

SETUP:

$ npm init -y
$ npm install --save sequelize
$ npm install --save pg pg-hstore
$ npm install -g sequelize-cli

CREATING DATABASES:

Creates a database under a name of seq-test:

$ createdb seq-test

Creates databases according to the config.json file:

$ sequelize db:create

config.json:

{
  "development": {
    "username": "kotpsot",
    "password": null,
    "database": "seq-test",
    "host": "127.0.0.1",
    "dialect": "postgres"
  },
  "test": {
    "username": "kotpsot",
    "password": null,
    "database": "seq-test2",
    "host": "127.0.0.1",
    "dialect": "postgres"
  },
  "production": {
    "username": "kotpsot",
    "password": null,
    "database": "seq-test3",
    "host": "127.0.0.1",
    "dialect": "postgres"
  }
}

In the config.json file there are three environments specified: development, test and production. If we want to create a database for a particular environment (for example for test), we type:

$ NODE_ENV=test sequelize db:create

By default, the database will be created in the development environment (defined by NODE_ENV).

CREATING MODELS + TABLES:

$ sequelize model:create --name Bird --attributes name:string,type:string

This way we create a model Bird. A file under this name is created in the models folder. The Bird model is a js class - it will contain all of the methods we will use for the instances of Bird. Examples:

• creating new birds.
• retrieve a particular bird from the database.
• retrieve all birds from the database.

At the same time, creating a model Bird creates a migration file (see inside the folder migrations) that creates a table. This table will be automatically called Birds. The name is in plural as it will store information about all of the instances of class Bird.

If you want to finalize the creation (or update) of the table inside a database, run:

$ sequelize db:migrate

NEXT STEPS:

• We will create new instances of Bird inside of a controller (router) and probably use express.js to do it.
• We will get the bird's info from a form and do something like: let bird = Bird.create({name: params.name ... })

DIAGRAMMING

What's the fuss about js and stuff.

+----------+
|BROWSER   |
|          |
+---+---+--+
    ^   |
    |   ^
+---+---+-------+        +-----------------+           +--+
|               |        |                 |           |  |
|CONTROLLER     | +----> |   MODEL         | +-------> |DB|
|(router)       |        |                 |           |  |
|               | <----+ |   Bird          | <-------+ |  |
|/bird          |        |   Cat etc.      |           |  |
|               |        |                 |           |  |
|               |        |                 |           |  |
+---------------+        +-----------------+           +--+

+     EXPRESS.JS              SEQUELIZE        +
|                                              |
+----------------------------------------------+

              NODE.JS

very nice! Thx Justyna!