Add the ability to specify table_name_prefix on individual modules

Signed-off-by: wycats <wycats@gmail.com>

activerecord/lib/active_record/base.rb

@@ -338,6 +338,9 @@ module ActiveRecord #:nodoc:
     # Accessor for the name of the prefix string to prepend to every table name. So if set to "basecamp_", all
     # table names will be named like "basecamp_projects", "basecamp_people", etc. This is a convenient way of creating a namespace
     # for tables in a shared database. By default, the prefix is the empty string.
+    #
+    # If you are organising your models within modules you can add a prefix to the models within a namespace by defining
+    # a singleton method in the parent module called table_name_prefix which returns your chosen prefix.
     cattr_accessor :table_name_prefix, :instance_writer => false
     @@table_name_prefix = ""
 
@@ -765,7 +768,7 @@ module ActiveRecord #:nodoc:
               contained = contained.singularize if parent.pluralize_table_names
               contained << '_'
             end
-            name = "#{table_name_prefix}#{contained}#{undecorated_table_name(base.name)}#{table_name_suffix}"
+            name = "#{modularized_table_name_prefix}#{contained}#{undecorated_table_name(base.name)}#{table_name_suffix}"
           end
 
         @quoted_table_name = nil
@@ -773,6 +776,10 @@ module ActiveRecord #:nodoc:
         name
       end
 
+      def modularized_table_name_prefix #:nodoc:
+        (parents.detect{ |p| p.respond_to?(:table_name_prefix) } || self).table_name_prefix
+      end
+
       # Defines the column name for use with single table inheritance
       # -- can be set in subclasses like so: self.inheritance_column = "type_id"
       def inheritance_column

activerecord/test/cases/modules_test.rb

@@ -82,4 +82,32 @@ class ModulesTest < ActiveRecord::TestCase
       end
     end
   end
+
+  def test_module_table_name_prefix
+    assert_equal 'prefixed_companies', MyApplication::Business::Prefixed::Company.table_name, 'inferred table_name for ActiveRecord model in module with table_name_prefix'
+    assert_equal 'prefixed_companies', MyApplication::Business::Prefixed::Nested::Company.table_name, 'table_name for ActiveRecord model in nested module with a parent table_name_prefix'
+    assert_equal 'companies', MyApplication::Business::Prefixed::Firm.table_name, 'explicit table_name for ActiveRecord model in module with table_name_prefix should not be prefixed'
+  end
+
+  def test_module_table_name_prefix_with_global_prefix
+    classes = [ MyApplication::Business::Company,
+                MyApplication::Business::Firm,
+                MyApplication::Business::Client,
+                MyApplication::Business::Client::Contact,
+                MyApplication::Business::Developer,
+                MyApplication::Business::Project,
+                MyApplication::Business::Prefixed::Company,
+                MyApplication::Business::Prefixed::Nested::Company,
+                MyApplication::Billing::Account ]
+
+    ActiveRecord::Base.table_name_prefix = 'global_'
+    classes.each(&:reset_table_name)
+    assert_equal 'global_companies', MyApplication::Business::Company.table_name, 'inferred table_name for ActiveRecord model in module without table_name_prefix'
+    assert_equal 'prefixed_companies', MyApplication::Business::Prefixed::Company.table_name, 'inferred table_name for ActiveRecord model in module with table_name_prefix'
+    assert_equal 'prefixed_companies', MyApplication::Business::Prefixed::Nested::Company.table_name, 'table_name for ActiveRecord model in nested module with a parent table_name_prefix'
+    assert_equal 'companies', MyApplication::Business::Prefixed::Firm.table_name, 'explicit table_name for ActiveRecord model in module with table_name_prefix should not be prefixed'
+  ensure
+    ActiveRecord::Base.table_name_prefix = ''
+    classes.each(&:reset_table_name)
+  end
 end

activerecord/test/models/company_in_module.rb

@@ -32,6 +32,23 @@ module MyApplication
       has_and_belongs_to_many :developers
     end
 
+    module Prefixed
+      def self.table_name_prefix
+        'prefixed_'
+      end
+
+      class Company < ActiveRecord::Base
+      end
+
+      class Firm < Company
+        self.table_name = 'companies'
+      end
+
+      module Nested
+        class Company < ActiveRecord::Base
+        end
+      end
+    end
   end
 
   module Billing