diff options
Diffstat (limited to 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb')
-rw-r--r-- | activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb | 115 |
1 files changed, 115 insertions, 0 deletions
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb b/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb index 22823a8c58..5814c2b711 100644 --- a/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb +++ b/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb @@ -642,6 +642,115 @@ module ActiveRecord end alias :remove_belongs_to :remove_reference + # Returns an array of foreign keys for the given table. + # The foreign keys are represented as +ForeignKeyDefinition+ objects. + def foreign_keys(table_name) + raise NotImplementedError, "foreign_keys is not implemented" + end + + # Adds a new foreign key. +from_table+ is the table with the key column, + # +to_table+ contains the referenced primary key. + # + # The foreign key will be named after the following pattern: <tt>fk_rails_<identifier></tt>. + # +identifier+ is a 10 character long random string. A custom name can be specified with + # the <tt>:name</tt> option. + # + # ====== Creating a simple foreign key + # + # add_foreign_key :articles, :authors + # + # generates: + # + # ALTER TABLE "articles" ADD CONSTRAINT articles_author_id_fk FOREIGN KEY ("author_id") REFERENCES "authors" ("id") + # + # ====== Creating a foreign key on a specific column + # + # add_foreign_key :articles, :users, column: :author_id, primary_key: "lng_id" + # + # generates: + # + # ALTER TABLE "articles" ADD CONSTRAINT fk_rails_58ca3d3a82 FOREIGN KEY ("author_id") REFERENCES "users" ("lng_id") + # + # ====== Creating a cascading foreign key + # + # add_foreign_key :articles, :authors, on_delete: :cascade + # + # generates: + # + # ALTER TABLE "articles" ADD CONSTRAINT articles_author_id_fk FOREIGN KEY ("author_id") REFERENCES "authors" ("id") ON DELETE CASCADE + # + # The +options+ hash can include the following keys: + # [<tt>:column</tt>] + # The foreign key column name on +from_table+. Defaults to <tt>to_table.singularize + "_id"</tt> + # [<tt>:primary_key</tt>] + # The primary key column name on +to_table+. Defaults to +id+. + # [<tt>:name</tt>] + # The constraint name. Defaults to <tt>fk_rails_<identifier></tt>. + # [<tt>:on_delete</tt>] + # Action that happens <tt>ON DELETE</tt>. Valid values are +:nullify+, +:cascade:+ and +:restrict+ + # [<tt>:on_update</tt>] + # Action that happens <tt>ON UPDATE</tt>. Valid values are +:nullify+, +:cascade:+ and +:restrict+ + def add_foreign_key(from_table, to_table, options = {}) + return unless supports_foreign_keys? + + options[:column] ||= foreign_key_column_for(to_table) + + options = { + column: options[:column], + primary_key: options[:primary_key], + name: foreign_key_name(from_table, options), + on_delete: options[:on_delete], + on_update: options[:on_update] + } + at = create_alter_table from_table + at.add_foreign_key to_table, options + + execute schema_creation.accept(at) + end + + # Removes the given foreign key from the table. + # + # Removes the foreign key on +accounts.branch_id+. + # + # remove_foreign_key :accounts, :branches + # + # Removes the foreign key on +accounts.owner_id+. + # + # remove_foreign_key :accounts, column: :owner_id + # + # Removes the foreign key named +special_fk_name+ on the +accounts+ table. + # + # remove_foreign_key :accounts, name: :special_fk_name + # + def remove_foreign_key(from_table, options_or_to_table = {}) + return unless supports_foreign_keys? + + if options_or_to_table.is_a?(Hash) + options = options_or_to_table + else + options = { column: foreign_key_column_for(options_or_to_table) } + end + + fk_name_to_delete = options.fetch(:name) do + fk_to_delete = foreign_keys(from_table).detect {|fk| fk.column == options[:column] } + + if fk_to_delete + fk_to_delete.name + else + raise ArgumentError, "Table '#{from_table}' has no foreign key on column '#{options[:column]}'" + end + end + + at = create_alter_table from_table + at.drop_foreign_key fk_name_to_delete + + execute schema_creation.accept(at) + end + + def foreign_key_column_for(table_name) # :nodoc: + "#{table_name.to_s.singularize}_id" + end + def dump_schema_information #:nodoc: sm_table = ActiveRecord::Migrator.schema_migrations_table_name @@ -852,6 +961,12 @@ module ActiveRecord def create_alter_table(name) AlterTable.new create_table_definition(name, false, {}) end + + def foreign_key_name(table_name, options) # :nodoc: + options.fetch(:name) do + "fk_rails_#{SecureRandom.hex(5)}" + end + end end end end |