Add change() method to migrations

[samdark]

The idea is to implement the same code as in up() and determine how to roll back migration based on it. Migration in this case should be like a query and a builder that has two modes: up and down.

It already exists in some third party libs such as https://phinx.org/

[pana1990]

reference of ruby on rails :

http://edgeguides.rubyonrails.org/active_record_migrations.html#using-the-change-method

[v0lume]

cool! like it!

[SonicGD]

:+1:

[ghost]

:+1: :)

[RedCatGirl]

:+1:

[samdark]

#593

[execut]

:+1: This idea is to reduce the cost of migration in 2 or more times. I know it by own experience. My implementation of this idea in yii2 extension: https://github.com/execut/yii2-migration

[samdark]

Phinx docs about that: http://docs.phinx.org/en/latest/migrations.html

[sergeymakinen]

I'd like to make it real later. ;)

[SamMousa]

I'm not a fan of creating reversible migrations that contain createTable or addColumn. They might be reversible from a structure perspective, but they lose data. Of course, if we implemented automated backups of those tables then i'm all for it!