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Module: ActiveRecord::Migration::Compatibility

Do not use. This module is for internal use only.
Relationships & Source Files
Namespace Children
Classes:
V4_2, V5_0, V5_1, V5_2, V6_0, V6_1, V7_0
Defined in: activerecord/lib/active_record/migration/compatibility.rb

Constant Summary

  • V7_1 =

    This file exists to ensure that old migrations run the same way they did before a ::Rails upgrade. e.g. if you write a migration on ::Rails 6.1, then upgrade to ::Rails 7, the migration should do the same thing to your database as it did when you were running ::Rails 6.1

    “Current” is an alias for ::ActiveRecord::Migration, it represents the current ::Rails version. New migration functionality that will never be backward compatible should be added directly to ::ActiveRecord::Migration.

    There are classes for each prior ::Rails version. Each class descends from the next ::Rails version, so: 7.0 < 7.1 5.2 < 6.0 < 6.1 < 7.0 < 7.1

    If you are introducing new migration functionality that should only apply from ::Rails 7 onward, then you should find the class that immediately precedes it (6.1), and override the relevant migration methods to undo your changes.

    For example, ::Rails 6 added a default value for the precision option on datetime columns. So in this file, the Compatibility::V5_2 class sets the value of precision to nil if it’s not explicitly provided. This way, the default value will not apply for migrations written for 5.2, but will for migrations written for 6.0.

    # File 'activerecord/lib/active_record/migration/compatibility.rb', line 33 
    Current

Class Method Summary

Class Method Details

.find(version)

[ GitHub ] 

  


# File 'activerecord/lib/active_record/migration/compatibility.rb', line 6



def self.find(version)
  version = version.to_s
  name = "V#{version.tr('.', '_')}"
  unless const_defined?(name)
    versions = constants.grep(/\AV[0-9_]+\z/).map { |s| s.to_s.delete("V").tr("_", ".").inspect }
    raise ArgumentError, "Unknown migration version #{version.inspect}; expected one of #{versions.sort.join(', ')}"
  end
  const_get(name)
end