iGary / chugs-db

Database change management for chugs

chugs-db

This is the change management tool for the chugs database. Migrations can be created, ran and rolled back using this tool.

Getting started

Install Knex (http://knexjs.org/)

yarn global add knex

Creating a migration

knex migrate:make <migration_name>

This will create a JavaScipt file in the /migrations folder with an up and down function. Simply add code to the up functions to describe how the database should look if this migration is applied and and add code to the down function to describe how the database should look if this migration is rolled back.

Example

// creating the table

exports.up = (knex, Promise) => {
  return knex.schema
    .createTable('product', table => {
      table.bigIncrements('id').primary();
      table.string('name');
      table.string('description');
      table.float('price');
      table.int('quantity');
      table.int('size');
    })
};

// drop the table
exports.down = (knex, Promise) => {
  return knex.schema
    .dropTableIfExists('product')
};

Running a migration

knex migrate:latest

This will run all migration scripts against the database.

Rolling back a migration

knex migrate:rollback

This will remove migration scripts from the database one at a time.

Creating a seed

knex seed:make <seed_name>

The folder structure for seeds is such that we have a /seeds folder and within that we have sub-folders representing different environments. e.g. /seeds/dev

When this command is executed, a JavaScript file named after the name given is created in the appropriate directory. Database entries can be entered here as JSON objects.

Example

exports.seed = function(knex, Promise) {
  // Deletes ALL existing entries
  return knex('table_name').del()
    .then(function () {
      // Inserts seed entries
      return knex('table_name').insert([
        { id: 1, name: 'test-name1', description: 'test-description1'},
        { id: 2, value: 'test-name2', description: 'test-description2' },
        { id: 3, value: 'test-name3', description: 'test-description3' },
        { id: 4, value: 'test-name4', description: 'test-description4' }
      ]);
    })

.then() functions can be chained on as required if seeding multiple tables.

Running a seed

knex seed:run

This will persist the data from seed files to the database.

Environments

The knexfile.js file located at the top level of this repository describes configuration for databases deployed in different environments. Sqlite3 is used for development which means that rather than a real database, a file is created in this folder that can be opened using SQLiteStudio.

SQLiteStudio can be installed by doing the following:

brew install sqlite3

More reading

http://knexjs.org/#Migrations