Rails 5: How to remove a column from a database?
To remove a column(country here) from table(sample_case)
rails generate migration RemoveCountryfromSampleCase country:string
Above command should generate a file YYYYMMDDHHMMSS_remove_countryfrom_sample_case.rb. under db/migrate folder
class RemoveCountryFromSampleCase < ActiveRecord::Migration[5.0]
def change
remove_column :sample_case, :country, :string
end
end
In my case (I was doing it for more than two columns) only this appears
class RemoveCountryFromSampleCase < ActiveRecord::Migration[5.0]
def change
end
end
remove_column line was not there so I added it manually and then fired the command
rails db:migrate
and it worked for me.
References https://stackoverflow.com/a/2963582 & Ruby guide on Active Record migration https://edgeguides.rubyonrails.org/active_record_migrations.html
Create migration file:
$ rails generate migration RemoveCountryFromSampleApps country:string
In generated migration file:
class RemoveCountryFromSampleApps < ActiveRecord::Migration
def change
remove_column :sample_apps, :country, :string
end
end
Then run:
rake db:migrate
To remove a column with migration:
rails g migration Remove..From.. col1:type col2:type col3:type
In your case:
rails g migration RemoveCountryFromSampleApps country:string
This will generate the following migration in Rails 5.0:
class RemoveCountryFromSampleApps < ActiveRecord::Migration[5.0]
def change
remove_column :sample_apps, :country, :string
end
end