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diff --git a/guides/source/generators.md b/guides/source/generators.md index 4a5377c206..14f451cbc9 100644 --- a/guides/source/generators.md +++ b/guides/source/generators.md @@ -1,3 +1,5 @@ +**DO NOT READ THIS FILE ON GITHUB, GUIDES ARE PUBLISHED ON http://guides.rubyonrails.org.** + Creating and Customizing Rails Generators & Templates ===================================================== @@ -8,6 +10,7 @@ After reading this guide, you will know: * How to see which generators are available in your application. * How to create a generator using templates. * How Rails searches for generators before invoking them. +* How Rails internally generates Rails code from the templates. * How to customize your scaffold by creating new generators. * How to customize your scaffold by changing generator templates. * How to use fallbacks to avoid overwriting a huge set of generators. @@ -23,19 +26,19 @@ When you create an application using the `rails` command, you are in fact using ```bash $ rails new myapp $ cd myapp -$ rails generate +$ bin/rails generate ``` You will get a list of all generators that comes with Rails. If you need a detailed description of the helper generator, for example, you can simply do: ```bash -$ rails generate helper --help +$ bin/rails generate helper --help ``` Creating Your First Generator ----------------------------- -Since Rails 3.0, generators are built on top of [Thor](https://github.com/erikhuda/thor). Thor provides powerful options parsing and a great API for manipulating files. For instance, let's build a generator that creates an initializer file named `initializer.rb` inside `config/initializers`. +Since Rails 3.0, generators are built on top of [Thor](https://github.com/erikhuda/thor). Thor provides powerful options for parsing and a great API for manipulating files. For instance, let's build a generator that creates an initializer file named `initializer.rb` inside `config/initializers`. The first step is to create a file at `lib/generators/initializer_generator.rb` with the following content: @@ -54,13 +57,13 @@ Our new generator is quite simple: it inherits from `Rails::Generators::Base` an To invoke our new generator, we just need to do: ```bash -$ rails generate initializer +$ bin/rails generate initializer ``` Before we go on, let's see our brand new generator description: ```bash -$ rails generate initializer --help +$ bin/rails generate initializer --help ``` Rails is usually able to generate good descriptions if a generator is namespaced, as `ActiveRecord::Generators::ModelGenerator`, but not in this particular case. We can solve this problem in two ways. The first one is calling `desc` inside our generator: @@ -82,7 +85,7 @@ Creating Generators with Generators Generators themselves have a generator: ```bash -$ rails generate generator initializer +$ bin/rails generate generator initializer create lib/generators/initializer create lib/generators/initializer/initializer_generator.rb create lib/generators/initializer/USAGE @@ -102,7 +105,7 @@ First, notice that we are inheriting from `Rails::Generators::NamedBase` instead We can see that by invoking the description of this new generator (don't forget to delete the old generator file): ```bash -$ rails generate initializer --help +$ bin/rails generate initializer --help Usage: rails generate initializer NAME [options] ``` @@ -130,7 +133,7 @@ end And let's execute our generator: ```bash -$ rails generate initializer core_extensions +$ bin/rails generate initializer core_extensions ``` We can see that now an initializer named core_extensions was created at `config/initializers/core_extensions.rb` with the contents of our template. That means that `copy_file` copied a file in our source root to the destination path we gave. The method `file_name` is automatically created when we inherit from `Rails::Generators::NamedBase`. @@ -169,7 +172,7 @@ end Before we customize our workflow, let's first see what our scaffold looks like: ```bash -$ rails generate scaffold User name:string +$ bin/rails generate scaffold User name:string invoke active_record create db/migrate/20130924151154_create_users.rb create app/models/user.rb @@ -191,23 +194,21 @@ $ rails generate scaffold User name:string create test/controllers/users_controller_test.rb invoke helper create app/helpers/users_helper.rb - invoke test_unit - create test/helpers/users_helper_test.rb invoke jbuilder create app/views/users/index.json.jbuilder create app/views/users/show.json.jbuilder invoke assets invoke coffee - create app/assets/javascripts/users.js.coffee + create app/assets/javascripts/users.coffee invoke scss - create app/assets/stylesheets/users.css.scss + create app/assets/stylesheets/users.scss invoke scss - create app/assets/stylesheets/scaffolds.css.scss + create app/assets/stylesheets/scaffolds.scss ``` Looking at this output, it's easy to understand how generators work in Rails 3.0 and above. The scaffold generator doesn't actually generate anything, it just invokes others to do the work. This allows us to add/replace/remove any of those invocations. For instance, the scaffold generator invokes the scaffold_controller generator, which invokes erb, test_unit and helper generators. Since each generator has a single responsibility, they are easy to reuse, avoiding code duplication. -Our first customization on the workflow will be to stop generating stylesheets, javascripts and test fixtures for scaffolds. We can achieve that by changing our configuration to the following: +Our first customization on the workflow will be to stop generating stylesheet, JavaScript and test fixture files for scaffolds. We can achieve that by changing our configuration to the following: ```ruby config.generators do |g| @@ -219,12 +220,12 @@ config.generators do |g| end ``` -If we generate another resource with the scaffold generator, we can see that stylesheets, javascripts and fixtures are not created anymore. If you want to customize it further, for example to use DataMapper and RSpec instead of Active Record and TestUnit, it's just a matter of adding their gems to your application and configuring your generators. +If we generate another resource with the scaffold generator, we can see that stylesheet, JavaScript and fixture files are not created anymore. If you want to customize it further, for example to use DataMapper and RSpec instead of Active Record and TestUnit, it's just a matter of adding their gems to your application and configuring your generators. To demonstrate this, we are going to create a new helper generator that simply adds some instance variable readers. First, we create a generator within the rails namespace, as this is where rails searches for generators used as hooks: ```bash -$ rails generate generator rails/my_helper +$ bin/rails generate generator rails/my_helper create lib/generators/rails/my_helper create lib/generators/rails/my_helper/my_helper_generator.rb create lib/generators/rails/my_helper/USAGE @@ -248,10 +249,10 @@ end end ``` -We can try out our new generator by creating a helper for users: +We can try out our new generator by creating a helper for products: ```bash -$ rails generate my_helper products +$ bin/rails generate my_helper products create app/helpers/products_helper.rb ``` @@ -279,10 +280,10 @@ end and see it in action when invoking the generator: ```bash -$ rails generate scaffold Post body:text +$ bin/rails generate scaffold Article body:text [...] invoke my_helper - create app/helpers/posts_helper.rb + create app/helpers/articles_helper.rb ``` We can notice on the output that our new helper was invoked instead of the Rails default. However one thing is missing, which is tests for our new generator and to do that, we are going to reuse old helpers test generators. @@ -342,6 +343,22 @@ end If you generate another resource, you can see that we get exactly the same result! This is useful if you want to customize your scaffold templates and/or layout by just creating `edit.html.erb`, `index.html.erb` and so on inside `lib/templates/erb/scaffold`. +Scaffold templates in Rails frequently use ERB tags; these tags need to be +escaped so that the generated output is valid ERB code. + +For example, the following escaped ERB tag would be needed in the template +(note the extra `%`)... + +```ruby +<%%= stylesheet_include_tag :application %> +``` + +...to generate the following output: + +```ruby +<%= stylesheet_include_tag :application %> +``` + Adding Generators Fallbacks --------------------------- @@ -365,7 +382,7 @@ end Now, if you create a Comment scaffold, you will see that the shoulda generators are being invoked, and at the end, they are just falling back to TestUnit generators: ```bash -$ rails generate scaffold Comment body:text +$ bin/rails generate scaffold Comment body:text invoke active_record create db/migrate/20130924143118_create_comments.rb create app/models/comment.rb @@ -387,14 +404,12 @@ $ rails generate scaffold Comment body:text create test/controllers/comments_controller_test.rb invoke my_helper create app/helpers/comments_helper.rb - invoke shoulda - create test/helpers/comments_helper_test.rb invoke jbuilder create app/views/comments/index.json.jbuilder create app/views/comments/show.json.jbuilder invoke assets invoke coffee - create app/assets/javascripts/comments.js.coffee + create app/assets/javascripts/comments.coffee invoke scss ``` @@ -507,7 +522,7 @@ Replaces text inside a file. gsub_file 'name_of_file.rb', 'method.to_be_replaced', 'method.the_replacing_code' ``` -Regular Expressions can be used to make this method more precise. You can also use append_file and prepend_file in the same way to place code at the beginning and end of a file respectively. +Regular Expressions can be used to make this method more precise. You can also use `append_file` and `prepend_file` in the same way to place code at the beginning and end of a file respectively. ### `application` |