Lock the table triggers are created for

[yourivdlans]

Hi!

There is a case where I want to lock the table the triggers are triggered on because I want to make sure nothing gets inserted, updated or deleted while the triggers are dropped and created.

Initially I started with just a execute('LOCK TABLES table WRITE;') at the start of the up and down methods.

But this changes the definition of the methods and after migrating the following warning is added to the schema.rb. And a generic execute with CREATE TRIGGER statement is used instead of the hair_trigger DSL.

WARNING: generating adapter-specific definition for table_after_insert_row_tr due to a mismatch. either there's a bug in hairtrigger or you've messed up your migrations and/or db :-/

To ensure we are still using the hair_trigger DSL and won't have this waning in our schema I created the following workaround:

module WrapUpAndDownWithLocks
  def up
    execute('LOCK TABLES table WRITE;')
    super
  ensure
    execute('UNLOCK TABLES;')
  end

  def down
    execute('LOCK TABLES table WRITE;')
    super
  ensure
    execute('UNLOCK TABLES;')
  end
end

class CreateTriggersTableInsertOrTableUpdateOrTableDelete < ActiveRecord::Migration[7.0]
  prepend WrapUpAndDownWithLocks

  def up
    # migration generated by hair_trigger
  end

  def down
    # migration generated by hair_trigger
  end
end

Its a bit hacky but gets the job done. Not sure if this problem is something that should be solved by the gem itself. But I wanted to share my solution here for anyone else running into this.