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Knut Ringheim Lunde
38,811 PointsUnderstanding Migration in Rails
In "Migrations and Relationsships" course in the video "Migrations" Hampton makes a Customer table with the fields: --> name, about, balance.
Later he makes an AddEmailAddress class where he adds a field to the Customer table. Why doesn't he just edit the Create Customers-file to include a email-field? I don't understand why he need to create a different file and class to do this? Or have I maybe completely misunderstood what he did in the first place?
2 Answers
Maciej Czuchnowski
36,441 PointsIn Rails the best practice is to introduce modifications to database schema in (mostly) reversible stages and these are called migrations. This way there is less risk that you will mess up something in your database and every step is reversible. It's similar to using Git - tracking every change to the database schema. You can then see how it all evolved over time. It's also helpful when working with other developers.
http://www.tutorialspoint.com/ruby-on-rails/rails-migrations.htm
Knut Ringheim Lunde
38,811 PointsOhh, thank you! That made sense :)
Maciej Czuchnowski
36,441 PointsMaciej Czuchnowski
36,441 PointsIn general, any changes should be introduced using a new file that gets applied after the previous migration files. Once created, a migration file should not be modified.