CODEWITHSUNDEEP
ruby-on-railsruby-on-rails-5
Kris
Kris

Reputation: 19938

Is there a way to know that a migration is running?

I have a model and I want to "register" meta-data about the columns, e.g. a label, description, in an initializer.

As part of this I want to check the column actually exists and raise if not.

However the column will not exist until the migration to add the column has been run.

Therefore I wish to skip this check if the environment is being initalized for the purposes of a migration.

Is there a way to know that a migration is running? Or that the db:migrate rake task triggered the loading of the environment...

class Preferences < ActiveRecord::Base
  def self.register(attrs)
    raise if migration_not_running? && !column_names.include?(attrs.fetch(:column_name))
    @schema << atrs
  end

  def self.schema
    @schema ||= []
  end

  private

  def self.migration_not_running?
    # ...?
  end    
end

Upvotes: 2

Views: 1327

Answers (1)

Igor Drozdov
Igor Drozdov

Reputation: 15045

What about checking if there are pending migrations, like the server does, when you try to load the views.

There's ActiveRecord::Migration.check_pending!, which raises ActiveRecord::PendingMigrationError if there are ones. But it uses connection.migration_context.needs_migration? logic under the hood, so it can be checked just like:

ActiveRecord::Base.connection.migration_context.needs_migration?

I understand, that it doesn't directly answers your question, but it's suggesting a possible alternative.

Upvotes: 3

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