Add :bulk => true option to change_table

activerecord/CHANGELOG

@@ -1,5 +1,18 @@
 *Rails 3.1.0 (unreleased)*
 
+* Add :bulk => true option to change_table to make all the schema changes defined in change_table block using a single ALTER statement. [Pratik Naik]
+
+  Example:
+
+  change_table(:users, :bulk => true) do |t|
+    t.string :company_name
+    t.change :birthdate, :datetime
+  end
+
+  This will now result in:
+
+    ALTER TABLE `users` ADD COLUMN `company_name` varchar(255), CHANGE `updated_at` `updated_at` datetime DEFAULT NULL
+
 * Removed support for accessing attributes on a has_and_belongs_to_many join table. This has been
   documented as deprecated behaviour since April 2006. Please use has_many :through instead.
   [Jon Leighton]

activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb

@@ -176,6 +176,13 @@ module ActiveRecord
       #    # Other column alterations here
       #  end
       #
+      # The +options+ hash can include the following keys:
+      # [<tt>:bulk</tt>]
+      #   Set this to true to make this a bulk alter query, such as
+      #   ALTER TABLE `users` ADD COLUMN age INT(11), ADD COLUMN birthdate DATETIME ...
+      #
+      #   Defaults to false.
+      #
       # ===== Examples
       # ====== Add a column
       #  change_table(:suppliers) do |t|
@@ -224,8 +231,14 @@ module ActiveRecord
       #
       # See also Table for details on
       # all of the various column transformation
-      def change_table(table_name)
-        yield Table.new(table_name, self)
+      def change_table(table_name, options = {})
+        if supports_bulk_alter? && options[:bulk]
+          recorder = ActiveRecord::Migration::CommandRecorder.new(self)
+          yield Table.new(table_name, recorder)
+          bulk_change_table(table_name, recorder.commands)
+        else
+          yield Table.new(table_name, self)
+        end
       end
 
       # Renames a table.
@@ -253,10 +266,7 @@ module ActiveRecord
       #  remove_column(:suppliers, :qualification)
       #  remove_columns(:suppliers, :qualification, :experience)
       def remove_column(table_name, *column_names)
-        raise ArgumentError.new("You must specify at least one column name.  Example: remove_column(:people, :first_name)") if column_names.empty?
-        column_names.flatten.each do |column_name|
-          execute "ALTER TABLE #{quote_table_name(table_name)} DROP #{quote_column_name(column_name)}"
-        end
+        columns_for_remove(table_name, *column_names).each {|column_name| execute "ALTER TABLE #{quote_table_name(table_name)} DROP #{column_name}" }
       end
       alias :remove_columns :remove_column
 
@@ -327,25 +337,8 @@ module ActiveRecord
       #
       # Note: SQLite doesn't support index length
       def add_index(table_name, column_name, options = {})
-        column_names = Array.wrap(column_name)
-        index_name   = index_name(table_name, :column => column_names)
-
-        if Hash === options # legacy support, since this param was a string
-          index_type = options[:unique] ? "UNIQUE" : ""
-          index_name = options[:name].to_s if options.key?(:name)
-        else
-          index_type = options
-        end
-
-        if index_name.length > index_name_length
-          raise ArgumentError, "Index name '#{index_name}' on table '#{table_name}' is too long; the limit is #{index_name_length} characters"
-        end
-        if index_name_exists?(table_name, index_name, false)
-          raise ArgumentError, "Index name '#{index_name}' on table '#{table_name}' already exists"
-        end
-        quoted_column_names = quoted_columns_for_index(column_names, options).join(", ")
-
-        execute "CREATE #{index_type} INDEX #{quote_column_name(index_name)} ON #{quote_table_name(table_name)} (#{quoted_column_names})"
+        index_name, index_type, index_columns = add_index_options(table_name, column_name, options)
+        execute "CREATE #{index_type} INDEX #{quote_column_name(index_name)} ON #{quote_table_name(table_name)} (#{index_columns})"
       end
 
       # Remove the given index from the table.
@@ -359,11 +352,7 @@ module ActiveRecord
       # Remove the index named by_branch_party in the accounts table.
       #   remove_index :accounts, :name => :by_branch_party
       def remove_index(table_name, options = {})
-        index_name = index_name(table_name, options)
-        unless index_name_exists?(table_name, index_name, true)
-          raise ArgumentError, "Index name '#{index_name}' on table '#{table_name}' does not exist"
-        end
-        remove_index!(table_name, index_name)
+        remove_index!(table_name, index_name_for_remove(table_name, options))
       end
 
       def remove_index!(table_name, index_name) #:nodoc:
@@ -469,7 +458,7 @@ module ActiveRecord
       end
 
       def type_to_sql(type, limit = nil, precision = nil, scale = nil) #:nodoc:
-        if native = native_database_types[type]
+        if native = native_database_types[type.to_sym]
           column_type_sql = (native.is_a?(Hash) ? native[:name] : native).dup
 
           if type == :decimal # ignore limit, use precision and scale
@@ -537,6 +526,45 @@ module ActiveRecord
           options.include?(:default) && !(options[:null] == false && options[:default].nil?)
         end
 
+        def add_index_options(table_name, column_name, options = {})
+          column_names = Array.wrap(column_name)
+          index_name   = index_name(table_name, :column => column_names)
+
+          if Hash === options # legacy support, since this param was a string
+            index_type = options[:unique] ? "UNIQUE" : ""
+            index_name = options[:name].to_s if options.key?(:name)
+          else
+            index_type = options
+          end
+
+          if index_name.length > index_name_length
+            raise ArgumentError, "Index name '#{index_name}' on table '#{table_name}' is too long; the limit is #{index_name_length} characters"
+          end
+          if index_name_exists?(table_name, index_name, false)
+            raise ArgumentError, "Index name '#{index_name}' on table '#{table_name}' already exists"
+          end
+          index_columns = quoted_columns_for_index(column_names, options).join(", ")
+
+          [index_name, index_type, index_columns]
+        end
+
+        def index_name_for_remove(table_name, options = {})
+          index_name = index_name(table_name, options)
+
+          unless index_name_exists?(table_name, index_name, true)
+            raise ArgumentError, "Index name '#{index_name}' on table '#{table_name}' does not exist"
+          end
+
+          index_name
+        end
+
+        def columns_for_remove(table_name, *column_names)
+          column_names = column_names.flatten
+
+          raise ArgumentError.new("You must specify at least one column name.  Example: remove_column(:people, :first_name)") if column_names.blank?
+          column_names.map {|column_name| quote_column_name(column_name) }
+        end
+
       private
       def table_definition
         TableDefinition.new(self)

activerecord/lib/active_record/connection_adapters/abstract_adapter.rb

@@ -77,6 +77,10 @@ module ActiveRecord
         false
       end
 
+      def supports_bulk_alter?
+        false
+      end
+
       # Does this adapter support savepoints? PostgreSQL and MySQL do,
       # SQLite < 3.6.8 does not.
       def supports_savepoints?

activerecord/lib/active_record/connection_adapters/mysql_adapter.rb

@@ -203,6 +203,10 @@ module ActiveRecord
         ADAPTER_NAME
       end
 
+      def supports_bulk_alter? #:nodoc:
+        true
+      end
+
       # Returns +true+ when the connection adapter supports prepared statement
       # caching, otherwise returns +false+
       def supports_statement_cache?
@@ -547,11 +551,23 @@ module ActiveRecord
         execute "RENAME TABLE #{quote_table_name(table_name)} TO #{quote_table_name(new_name)}"
       end
 
+      def bulk_change_table(table_name, operations) #:nodoc:
+        sqls = operations.map do |command, args|
+          table, arguments = args.shift, args
+          method = :"#{command}_sql"
+
+          if respond_to?(method)
+            send(method, table, *arguments)
+          else
+            raise "Unknown method called : #{method}(#{arguments.inspect})"
+          end
+        end.flatten.join(", ")
+
+        execute("ALTER TABLE #{quote_table_name(table_name)} #{sqls}")
+      end
+
       def add_column(table_name, column_name, type, options = {})
-        add_column_sql = "ALTER TABLE #{quote_table_name(table_name)} ADD #{quote_column_name(column_name)} #{type_to_sql(type, options[:limit], options[:precision], options[:scale])}"
-        add_column_options!(add_column_sql, options)
-        add_column_position!(add_column_sql, options)
-        execute(add_column_sql)
+        execute("ALTER TABLE #{quote_table_name(table_name)} #{add_column_sql(table_name, column_name, type, options)}")
       end
 
       def change_column_default(table_name, column_name, default) #:nodoc:
@@ -570,34 +586,11 @@ module ActiveRecord
       end
 
       def change_column(table_name, column_name, type, options = {}) #:nodoc:
-        column = column_for(table_name, column_name)
-
-        unless options_include_default?(options)
-          options[:default] = column.default
-        end
-
-        unless options.has_key?(:null)
-          options[:null] = column.null
-        end
-
-        change_column_sql = "ALTER TABLE #{quote_table_name(table_name)} CHANGE #{quote_column_name(column_name)} #{quote_column_name(column_name)} #{type_to_sql(type, options[:limit], options[:precision], options[:scale])}"
-        add_column_options!(change_column_sql, options)
-        add_column_position!(change_column_sql, options)
-        execute(change_column_sql)
+        execute("ALTER TABLE #{quote_table_name(table_name)} #{change_column_sql(table_name, column_name, type, options)}")
       end
 
       def rename_column(table_name, column_name, new_column_name) #:nodoc:
-        options = {}
-        if column = columns(table_name).find { |c| c.name == column_name.to_s }
-          options[:default] = column.default
-          options[:null] = column.null
-        else
-          raise ActiveRecordError, "No such column: #{table_name}.#{column_name}"
-        end
-        current_type = select_one("SHOW COLUMNS FROM #{quote_table_name(table_name)} LIKE '#{column_name}'")["Type"]
-        rename_column_sql = "ALTER TABLE #{quote_table_name(table_name)} CHANGE #{quote_column_name(column_name)} #{quote_column_name(new_column_name)} #{current_type}"
-        add_column_options!(rename_column_sql, options)
-        execute(rename_column_sql)
+        execute("ALTER TABLE #{quote_table_name(table_name)} #{rename_column_sql(table_name, column_name, new_column_name)}")
       end
 
       # Maps logical Rails types to MySQL-specific data types.
@@ -680,6 +673,69 @@ module ActiveRecord
           end
         end
 
+        def add_column_sql(table_name, column_name, type, options = {})
+          add_column_sql = "ADD #{quote_column_name(column_name)} #{type_to_sql(type, options[:limit], options[:precision], options[:scale])}"
+          add_column_options!(add_column_sql, options)
+          add_column_position!(add_column_sql, options)
+          add_column_sql
+        end
+
+        def remove_column_sql(table_name, *column_names)
+          columns_for_remove(table_name, *column_names).map {|column_name| "DROP #{column_name}" }
+        end
+        alias :remove_columns_sql :remove_column
+
+        def change_column_sql(table_name, column_name, type, options = {})
+          column = column_for(table_name, column_name)
+
+          unless options_include_default?(options)
+            options[:default] = column.default
+          end
+
+          unless options.has_key?(:null)
+            options[:null] = column.null
+          end
+
+          change_column_sql = "CHANGE #{quote_column_name(column_name)} #{quote_column_name(column_name)} #{type_to_sql(type, options[:limit], options[:precision], options[:scale])}"
+          add_column_options!(change_column_sql, options)
+          add_column_position!(change_column_sql, options)
+          change_column_sql
+        end
+
+        def rename_column_sql(table_name, column_name, new_column_name)
+          options = {}
+
+          if column = columns(table_name).find { |c| c.name == column_name.to_s }
+            options[:default] = column.default
+            options[:null] = column.null
+          else
+            raise ActiveRecordError, "No such column: #{table_name}.#{column_name}"
+          end
+
+          current_type = select_one("SHOW COLUMNS FROM #{quote_table_name(table_name)} LIKE '#{column_name}'")["Type"]
+          rename_column_sql = "CHANGE #{quote_column_name(column_name)} #{quote_column_name(new_column_name)} #{current_type}"
+          add_column_options!(rename_column_sql, options)
+          rename_column_sql
+        end
+
+        def add_index_sql(table_name, column_name, options = {})
+          index_name, index_type, index_columns = add_index_options(table_name, column_name, options)
+          "ADD #{index_type} INDEX #{index_name} (#{index_columns})"
+        end
+
+        def remove_index_sql(table_name, options = {})
+          index_name = index_name_for_remove(table_name, options)
+          "DROP INDEX #{index_name}"
+        end
+
+        def add_timestamps_sql(table_name)
+          [add_column_sql(table_name, :created_at, :datetime), add_column_sql(table_name, :updated_at, :datetime)]
+        end
+
+        def remove_timestamps_sql(table_name)
+          [remove_column_sql(table_name, :updated_at), remove_column_sql(table_name, :created_at)]
+        end
+
       private
         def connect
           encoding = @config[:encoding]

activerecord/lib/active_record/migration/command_recorder.rb

@@ -40,7 +40,7 @@ module ActiveRecord
         @commands.reverse.map { |name, args|
           method = :"invert_#{name}"
           raise IrreversibleMigration unless respond_to?(method, true)
-          __send__(method, args)
+          send(method, args)
         }
       end
 
@@ -48,12 +48,16 @@ module ActiveRecord
         super || delegate.respond_to?(*args)
       end
 
-      def send(method, *args) # :nodoc:
-        return super unless respond_to?(method)
-        record(method, args)
+      [:create_table, :rename_table, :add_column, :remove_column, :rename_index, :rename_column, :add_index, :remove_index, :add_timestamps, :remove_timestamps, :change_column, :change_column_default].each do |method|
+        class_eval <<-EOV, __FILE__, __LINE__ + 1
+          def #{method}(*args)
+            record(:"#{method}", args)
+          end
+        EOV
       end
 
       private
+
       def invert_create_table(args)
         [:drop_table, args]
       end
@@ -86,6 +90,14 @@ module ActiveRecord
       def invert_add_timestamps(args)
         [:remove_timestamps, args]
       end
+
+      # Forwards any missing method call to the \target.
+      def method_missing(method, *args, &block)
+        @delegate.send(method, *args, &block)
+      rescue NoMethodError => e
+        raise e, e.message.sub(/ for #<.*$/, " via proxy for #{@delegate}")
+      end
+
     end
   end
 end

activerecord/test/cases/migration/command_recorder_test.rb

@@ -16,7 +16,7 @@ module ActiveRecord
 
       def test_send_calls_super
         assert_raises(NoMethodError) do
-          @recorder.send(:create_table, :horses)
+          @recorder.send(:non_existing_method, :horses)
         end
       end
 

activerecord/test/cases/migration_test.rb

@@ -1923,6 +1923,144 @@ if ActiveRecord::Base.connection.supports_migrations?
     end
   end
 
+  class AlterTableMigrationsTest < ActiveRecord::TestCase
+    def setup
+      @connection = Person.connection
+      @connection.create_table(:delete_me, :force => true) {|t| }
+    end
+
+    def teardown
+      Person.connection.drop_table(:delete_me) rescue nil
+    end
+
+    def test_adding_multiple_columns
+      assert_queries(1) do
+        with_bulk_change_table do |t|
+          t.column :name, :string
+          t.string :qualification, :experience
+          t.integer :age, :default => 0
+          t.date :birthdate
+          t.timestamps
+        end
+      end
+
+      assert_equal 8, columns.size
+      [:name, :qualification, :experience].each {|s| assert_equal :string, column(s).type }
+      assert_equal 0, column(:age).default
+    end
+
+    def test_removing_columns
+      with_bulk_change_table do |t|
+        t.string :qualification, :experience
+      end
+
+      [:qualification, :experience].each {|c| assert column(c) }
+
+      assert_queries(1) do
+        with_bulk_change_table do |t|
+          t.remove :qualification, :experience
+          t.string :qualification_experience
+        end
+      end
+
+      [:qualification, :experience].each {|c| assert ! column(c) }
+      assert column(:qualification_experience)
+    end
+
+    def test_adding_indexes
+      with_bulk_change_table do |t|
+        t.string :username
+        t.string :name
+        t.integer :age
+      end
+
+      # Adding an index fires a query everytime to check if an index already exists or not
+      assert_queries(3) do
+        with_bulk_change_table do |t|
+          t.index :username, :unique => true, :name => :awesome_username_index
+          t.index [:name, :age]
+        end
+      end
+
+      assert_equal 2, indexes.size
+
+      name_age_index = index(:index_delete_me_on_name_and_age)
+      assert_equal ['name', 'age'].sort, name_age_index.columns.sort
+      assert ! name_age_index.unique
+
+      assert index(:awesome_username_index).unique
+    end
+
+    def test_removing_index
+      with_bulk_change_table do |t|
+        t.string :name
+        t.index :name
+      end
+
+      assert index(:index_delete_me_on_name)
+
+      assert_queries(3) do
+        with_bulk_change_table do |t|
+          t.remove_index :name
+          t.index :name, :name => :new_name_index, :unique => true
+        end
+      end
+
+      assert ! index(:index_delete_me_on_name)
+
+      new_name_index = index(:new_name_index)
+      assert new_name_index.unique
+    end
+
+    def test_changing_columns
+      with_bulk_change_table do |t|
+        t.string :name
+        t.date :birthdate
+      end
+
+      assert ! column(:name).default
+      assert_equal :date, column(:birthdate).type
+
+      assert_queries(1) do
+        with_bulk_change_table do |t|
+          t.change :name, :string, :default => 'NONAME'
+          t.change :birthdate, :datetime
+        end
+      end
+
+      assert_equal 'NONAME', column(:name).default
+      assert_equal :datetime, column(:birthdate).type
+    end
+
+    protected
+
+    def with_bulk_change_table
+      # Reset columns/indexes cache as we're changing the table
+      @columns = @indexes = nil
+
+      Person.connection.change_table(:delete_me, :bulk => true) do |t|
+        yield t
+      end
+    end
+
+    def column(name)
+      columns.detect {|c| c.name == name.to_s }
+    end
+
+    def columns
+      @columns ||= Person.connection.columns('delete_me')
+    end
+
+    def index(name)
+      indexes.detect {|i| i.name == name.to_s }
+    end
+
+    def indexes
+      @indexes ||= Person.connection.indexes('delete_me')
+    end
+
+  end
+
   class CopyMigrationsTest < ActiveRecord::TestCase
     def setup
     end