update

src/b/2012-03-16-generate-rails-migrations-that-automagically-add-your-change.md

@@ -6,70 +6,45 @@ comments: false
 collection: rails
 ---
 
-Rails's generators can be pretty cool, and by knowing some simple tricks
-you can save yourself from tedious work:
+Rails' generators can pump out code and save you from tedious work.
 
-`rails g model person name:string age:integer`
+This command generates a person model with a name and age:
 
-Rails developers should probably know that this will generate a model
-containing name and age fields, with string and integer data types
-respectively.
+    rails g model person name:string age:integer
 
-You can even specify attribute options, let's make a new book model with
-an indexed price field that needs the given precision 1 and scale 2:
+When you generator a decimal field you can specify the precision --- the total number of digits in the number, and the scale --- the number of digits following the decimal point.
 
-`rails g model book price:decimal{1,2}:index`
+    rails g model book price:decimal{5,2}:index
 
-This has slightly more magic since it's not apparent what the command does just
-by looking at it, e.g. you have to know the precision/scale order.
+When you generate a migration, by following Rails' migration name conventions, Rails will generate the fields. For example, this command generates the following migration:
 
-Things can get even more magical. By naming your migrations in the form of:
+    rails g migration add_body_and_pid_to_people body:string:index pid:integer:uniq
 
-`add/remove column [and ...] to/from table`
+	class AddBodyAndPidToPersons < ActiveRecord::Migration
+	  def change
+	    add_column :persons, :body, :string
+	    add_index :persons, :body
 
-Rails will generate your migration and add in the change you intend to make.
+	    add_column :persons, :pid, :integer
+	    add_index :persons, :pid, :unique => true
+	  end
+	end
 
-So let's say we want to add an indexed body and unique person id to the people
-table:
+You should always check the generated migration though, it's not perfect. The migration generated by this command should remove the index as well.
 
-`rails g migration add_body_and_pid_to_people body:string:index pid:integer:uniq`
+    rails g migration remove_body_from_people body:string:index
 
-Will generate this migration:
+However, the generated migration does not remove the index.
 
-``` ruby
-class AddBodyAndPidToPersons < ActiveRecord::Migration
-  def change
-    add_column :persons, :body, :string
-    add_index :persons, :body
+	class RemoveBodyFromPeople < ActiveRecord::Migration
+	  def up
+	    remove_column :people, :body
+	  end
 
-    add_column :persons, :pid, :integer
-    add_index :persons, :pid, :unique => true
-  end
-end
-```
+	  def down
+	    add_column :people, :body, :string
+	  end
+	end
 
-Pretty cool, huh?
 
-You should always check the generated migration though, it's not perfect.
-
-`rails g migration add_body_to_people body:string:index`
-
-Generates the migration we expect, however,
-
-`rails g migration remove_body_from_people body:string:index`
-
-``` ruby
-class RemoveBodyFromPeople < ActiveRecord::Migration
-  def up
-    remove_column :people, :body
-  end
-
-  def down
-    add_column :people, :body, :string
-  end
-end
-```
-
-Notice that the specified index will not be added or removed.
-
-Edit: I fixed this issue and it's [merged in Rails](https://github.com/rails/rails/commit/b2a59388b2ad281ccce1f72dd5fda09ca746dc32).
+Update:  [I fixed this issue Rails](https://github.com/rails/rails/commit/b2a59388b2ad281ccce1f72dd5fda09ca746dc32).