Automatically generate add/remove column commands in specially named migrations like AddLocationToEvent. Closes #9006 [zenspider]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@7216 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

railties/CHANGELOG

@@ -1,5 +1,7 @@
 *SVN*
 
+* Automatically generate add/remove column commands in specially named migrations like AddLocationToEvent.  Closes #9006 [zenspider]
+
 * Default to plural table name in Rails Generator if ActiveRecord is not present.  Closes #8963 [evan]
 
 * Added rake routes for listing all the defined routes in the system #8795 [josh]

railties/lib/rails_generator/generators/components/migration/USAGE

@@ -3,8 +3,22 @@ Description:
     CamelCased or under_scored, as an argument. A migration class is generated
     in db/migrate prefixed by the latest migration number.
 
+    You can name your migration in either of these formats to generate add/remove
+    column lines: AddColumnToTable or RemoveColumnFromTable
+
 Example:
     `./script/generate migration AddSslFlag`
 
     With 4 existing migrations, this creates the AddSslFlag migration in
     db/migrate/005_add_ssl_flag.rb
+
+    `./script/generate migration AddSslFlagToAccount`
+    
+    This will create the AddSslFlagToAccount in db/migrate/005_add_ssl_flag_to_account.rb with
+    this in the Up migration:
+
+      add_column :accounts, :ssl_flag, :type, :null => :no?, :default => :maybe?
+
+    And this in the Down migration:
+    
+      remove_column :accounts, :ssl_flag

railties/lib/rails_generator/generators/components/migration/migration_generator.rb

@@ -4,4 +4,17 @@ class MigrationGenerator < Rails::Generator::NamedBase
       m.migration_template 'migration.rb', 'db/migrate'
     end
   end
+
+  def auto_migration direction
+    case class_name.underscore
+    when /^(add|remove)_(.*)_(?:to|from)_(.*)/ then
+      action, col, tbl = $1, $2, $3.pluralize
+
+      unless (action == "add") ^ (direction == :up) then
+        %(\n    add_column :#{tbl}, :#{col}, :type, :null => :no?, :default => :maybe?)
+      else
+        %(\n    remove_column :#{tbl}, :#{col})
+      end
+    end
+  end
 end

railties/lib/rails_generator/generators/components/migration/templates/migration.rb

@@ -1,7 +1,7 @@
 class <%= class_name.underscore.camelize %> < ActiveRecord::Migration
-  def self.up
+  def self.up<%= auto_migration :up %>
   end
 
-  def self.down
+  def self.down<%= auto_migration :down %>
   end
 end