Is it possible to output the SQL change scripts that 'rake db:migrate' produces?

Question

Is it possible to output the SQL change scripts that \'rake db:migrate\' produces?

Answer 1

You can run preview SQL in rails console like this:

ActiveRecord::Base.connection.change_table(:events) do |t|
  t.integer :submission_id, default: 5, null: false
end
#=> ALTER TABLE `events` ADD `submission_id` int DEFAULT 5 NOT NULL

So, just prepend your ordinary migration methods with ActiveRecord::Base.connection. and you are good to go.

There is also rails console --sandbox mode which rollbacks changes after you close the console. Though check if it works for your project, somehow for our project with rails 5 + MySQL it doesn't roll back DDL changes.

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If you have migration files ready, you can also run it directly:

ActiveRecord::MigrationContext.new("db/migrate").migrate
ActiveRecord::MigrationContext.new("db/migrate").rollback