1 files changed, 57 insertions, 3 deletions
diff --git a/railties/lib/rails/generators/generated_attribute.rb b/railties/lib/rails/generators/generated_attribute.rb
index 816d82cac3..61479b9068 100644
--- a/railties/lib/rails/generators/generated_attribute.rb
+++ b/railties/lib/rails/generators/generated_attribute.rb
@@ -1,14 +1,48 @@
 require 'active_support/time'
 require 'active_support/core_ext/object/inclusion'
+require 'active_support/core_ext/object/blank'
 
 module Rails
   module Generators
     class GeneratedAttribute
       attr_accessor :name, :type
+      attr_reader   :attr_options
 
-      def initialize(name, type)
-        type = :string if type.blank?
-        @name, @type = name, type.to_sym
+      class << self
+        def parse(column_definition)
+          name, type, has_index = column_definition.split(':')
+
+          # if user provided "name:index" instead of "name:string:index"
+          # type should be set blank so GeneratedAttribute's constructor
+          # could set it to :string
+          has_index, type = type, nil if %w(index uniq).include?(type)
+
+          type, attr_options = *parse_type_and_options(type)
+          new(name, type, has_index, attr_options)
+        end
+
+        private
+
+        # parse possible attribute options like :limit for string/text/binary/integer or :precision/:scale for decimals
+        # when declaring options curly brackets should be used
+        def parse_type_and_options(type)
+          case type
+          when /(string|text|binary|integer)\{(\d+)\}/
+            return $1, :limit => $2.to_i
+          when /decimal\{(\d+),(\d+)\}/
+            return :decimal, :precision => $1.to_i, :scale => $2.to_i
+          else
+            return type, {}
+          end
+        end
+      end
+
+      def initialize(name, type=nil, index_type=false, attr_options={})
+        @name           = name
+        @type           = (type.presence || :string).to_sym
+        @has_index      = %w(index uniq).include?(index_type)
+        @has_uniq_index = %w(uniq).include?(index_type)
+        @attr_options   = attr_options
       end
 
       def field_type
@@ -45,9 +79,29 @@ module Rails
         name.to_s.humanize
       end
 
+      def index_name
+        reference? ? "#{name}_id" : name
+      end
+
       def reference?
         self.type.in?([:references, :belongs_to])
       end
+
+      def has_index?
+        @has_index
+      end
+
+      def has_uniq_index?
+        @has_uniq_index
+      end
+
+      def inject_options
+        "".tap { |s| @attr_options.each { |k,v| s << ", #{k}: #{v.inspect}" } }
+      end
+
+      def inject_index_options
+        has_uniq_index? ? ", unique: true" : ""
+      end
     end
   end
 end