class OnlineMigrations::BackgroundMigrations::BackgroundMigrationClassValidator

@private

Public Instance Methods

validate(record) click to toggle source
# File lib/online_migrations/background_migrations/background_migration_class_validator.rb, line 7
def validate(record)
  relation = record.migration_relation
  migration_name = record.migration_name

  unless relation.is_a?(ActiveRecord::Relation)
    record.errors.add(
      :migration_name,
      "#{migration_name}#relation must return an ActiveRecord::Relation object"
    )
    return
  end

  if relation.joins_values.present? && !record.batch_column_name.to_s.include?(".")
    record.errors.add(
      :batch_column_name,
      "must be a fully-qualified column if you join a table"
    )
  end

  if relation.arel.orders.present? || relation.arel.taken.present?
    record.errors.add(
      :migration_name,
      "#{migration_name}#relation cannot use ORDER BY or LIMIT due to the way how iteration with a cursor is designed. " \
      "You can use other ways to limit the number of rows, e.g. a WHERE condition on the primary key column."
    )
  end
end