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Class: ActiveRecord::Schema

Relationships & Source Files
Namespace Children
Modules:
Definition
Super Chains via Extension / Inclusion / Inheritance
Class Chain:
self, Migration
Instance Chain:
self, Definition, Migration
Inherits: ActiveRecord::Migration::Current
Defined in: activerecord/lib/active_record/schema.rb

Overview

Allows programmers to programmatically define a schema in a portable DSL. This means you can define tables, indexes, etc. without using SQL directly, so your applications can more easily support multiple databases.

Usage:

ActiveRecord::Schema[7.0].define do
  create_table :authors do |t|
    t.string :name, null: false
  end

  add_index :authors, :name, :unique

  create_table :posts do |t|
    t.integer :author_id, null: false
    t.string :subject
    t.text :body
    t.boolean :private, default: false
  end

  add_index :posts, :author_id
end

Schema is only supported by database adapters that also support migrations, the two features being very similar.

Class Attribute Summary

Migration - Inherited

.verbose

Class Method Summary

Migration - Inherited

.[],
.check_all_pending!

Raises PendingMigrationError error if any migrations are pending for all database configurations in an environment.
.check_pending!

Raises PendingMigrationError error if any migrations are pending.
.current_version,
.disable_ddl_transaction!

Disable the transaction wrapping this migration.
.load_schema_if_pending!, .migrate, .new

Instance Attribute Summary

Migration - Inherited

#name, #reverting?, #verbose, #version

Instance Method Summary

Migration - Inherited

#announce, #connection, #copy, #down, #exec_migration, #execution_strategy, #method_missing,
#migrate

Execute this migration in the named direction.
#next_migration_number

Determines the version number of the next migration.
#proper_table_name

Finds the correct table name given an Active Record object.
#reversible

Used to specify an operation that can be run in one direction or another.
#revert

Reverses the migration commands for the given block and the given migrations.
#run

Runs the given migration classes.
#say

Takes a message argument and outputs it as is.
#say_with_time

Outputs text along with how long it took to run its block.
#suppress_messages

Takes a block as an argument and suppresses any output generated by the block.
#up,
#up_only

Used to specify an operation that is only run when migrating up (for example, populating a new column with its initial values).
#write

Constructor Details

This class inherits a constructor from ActiveRecord::Migration

Dynamic Method Handling

This class handles dynamic methods through the method_missing method in the class ActiveRecord::Migration

Class Method Details

.[](version)

[ GitHub ] 

  


# File 'activerecord/lib/active_record/schema.rb', line 68



def self.[](version)
  @class_for_version ||= {}
  @class_for_version[version] ||= Class.new(Migration::Compatibility.find(version)) do
    include Definition
  end
end