add uuid primary key support

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

@@ -64,8 +64,9 @@ def columns; @columns_hash.values; end
 
       # Appends a primary key definition to the table definition.
       # Can be called multiple times, but this is probably not a good idea.
-      def primary_key(name)
-        column(name, :primary_key, primary_key: true)
+      def primary_key(name, type = :primary_key, options = {})
+        options[:primary_key] = true
+        column(name, type, options)
       end
 
       # Returns a ColumnDefinition for the column with name +name+.

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

@@ -178,7 +178,7 @@ def create_table(table_name, options = {})
             Base.get_primary_key table_name.to_s.singularize
           }
 
-          td.primary_key pk
+          td.primary_key pk, options.fetch(:id, :primary_key), options
         end
 
         yield td if block_given?

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

@@ -10,6 +10,15 @@ def visit_AddColumn(o)
           add_column_options!(sql, column_options(o))
         end
 
+        def visit_ColumnDefinition(o)
+          sql = super
+          if o.primary_key? && o.type == :uuid
+            sql << " PRIMARY KEY "
+            add_column_options!(sql, column_options(o))
+          end
+          sql
+        end
+
         def add_column_options!(sql, options)
           if options[:array] || options[:column].try(:array)
             sql << '[]'

activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb

@@ -330,6 +330,13 @@ def json(name, options = {})
       class TableDefinition < ActiveRecord::ConnectionAdapters::TableDefinition
         include ColumnMethods
 
+        def primary_key(name, type = :primary_key, options = {})
+          return super unless type == :uuid
+          options[:default] ||= 'uuid_generate_v4()'
+          options[:primary_key] = true
+          column name, type, options
+        end
+
         def column(name, type = nil, options = {})
           super
           column = self[name]

activerecord/test/cases/adapters/postgresql/uuid_test.rb

@@ -35,6 +35,16 @@ def teardown
     @connection.execute 'drop table if exists pg_uuids'
   end
 
+  def test_id_is_uuid
+    assert_equal :uuid, UUID.columns_hash['id'].type
+    assert UUID.primary_key
+  end
+
+  def test_id_has_a_default
+    u = UUID.create
+    assert_not_nil u.id
+  end
+
   def test_auto_create_uuid
     u = UUID.create
     u.reload