Tony Lâmpada Tony Lâmpada - 1 month ago 5
Ruby Question

How to ignore a missing migration with "sequel -s"

I'm trying to use Sequel to manage migrations for my database, and sometimes, due to feature-branching, there are moments when the database has migrations applied that don't exist in the filesystem.

By default, when I apply migrations with

sequel -m
on those situations I get this error:

Error: Sequel::Migrator::Error: Applied migration files not in file system


Looking at the docs I can see that there's an option for that:


Ignoring missing migrations¶ ↑



In some cases, you may want to allow a migration in the database that does not exist in the filesystem (deploying to an older version of code without running a down migration when deploy auto-migrates, for example). If required, you can pass :allow_missing_migration_files => true as an option. This will stop errors from being raised if there are migrations in the database that do not exist in the filesystem.


Nice!

How do I pass that
allow_missing_migration_files
option to
sequel -m
?

Answer

I think you'll have to use the Sequel::Migrator API for that. Something like

Sequel::Migrator.run(DB, '/path/to/migrations/dir', allow_missing_migration_files: true)

You can also wrap this behavior in a Rake task, so you don't have to start a console to run migrations.

namespace :db do
  desc "Run migrations ignoring the missing ones"
  task :migrate_without_missing, [:version] do |t, args|
    require "sequel"
    Sequel.extension :migration
    db = Sequel.connect(ENV.fetch("DATABASE_URL"))
    if args[:version]
      puts "Migrating to version #{args[:version]}"
      Sequel::Migrator.run(db, "db/migrations", target: args[:version].to_i, allow_missing_migration_files: true)
    else
      puts "Migrating to latest"
      Sequel::Migrator.run(db, "db/migrations", allow_missing_migration_files: true)
    end
  end
end

Then run rake db:migrate_without_missing.

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