Migrations #

Database migrations are a technique used in software development to manage changes to a database schema over time. A database schema is the structure of a database that defines the tables, columns, relationships, and constraints that make up the data model.

When changes are made to the database schema, such as adding a new table or column, modifying an existing column's data type, or changing a relationship between tables, database migrations allow developers to update the schema and propagate those changes to all instances of the database.

Generating Migrations #

You can quickly generate migrations using the g:migration command:

php leaf g:migration <Name>

# example
php leaf g:migration flights

The new migration will be placed in your app/database/migrations directory. Each migration file name begins with a timestamp.

Migration Structure #

A migration class contains two methods: up and down. The up method is used to add new tables, columns, or indexes to your database, while the down method should reverse the operations performed by the up method.

You can create and modify tables in the both of these methods. In this example, we create a posts table:

<?php
namespace App\Database\Migrations;

use Leaf\Database;
use Illuminate\Database\Schema\Blueprint;

class CreateUsers extends Database {
  /**
   * Run the migrations.
   *
   * @return void
   */
  public function up()
  {
    if (!$this->capsule::schema()->hasTable("posts")):
      $this->capsule::schema()->create("posts", function (Blueprint $table) {
        $table->increments('id');
        $table->string('author_id');
        $table->string('title');
        $table->text('body');
        $table->timestamps();
      });
    endif;
  }

  /**
   * Reverse the migrations.
   *
   * @return void
   */
  public function down()
  {
    $this->capsule::schema()->dropIfExists("posts");
  }
}

Running migrations #

To run all of your outstanding migrations, execute the db:migrate command:

php leaf db:migrate

You may also run seeds alongside your migrations if you wish to do so:

php leaf db:migrate -s
# or
php leaf db:migrate --seed

You can also choose to run a specific migration file:

php leaf db:migrate -f users

Rolling Back Migrations #

To roll back the latest migration operation, you may use the db:rollback command.

php leaf db:rollback

You may roll back a limited number of migrations by providing the step option to the rollback command. For example, the following command will roll back the last two migrations:

php leaf db:rollback -s 2

To roll back all migrations, you can just pass all as the step option.

php leaf db:rollback --step all

You can also rollback a specific migration file:

php leaf db:rollback -f users

Refreshing Migrations #

If you would like to reset your database and re-run all of your migrations with seeds, you may use the db:reset command. This command will drop all tables in your database and re-run all of your migrations:

php leaf db:reset

If you want to prevent seeds from running, you can use the --noSeed option:

php leaf db:reset --noSeed

Next Steps #

Follow along with the next steps to learn more about Leaf MVC.