267 lines
6.6 KiB
Markdown
267 lines
6.6 KiB
Markdown
Rails Application Templates
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===========================
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Application templates are simple Ruby files containing DSL for adding gems/initializers etc. to your freshly created Rails project or an existing Rails project.
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After reading this guide, you will know:
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* How to use templates to generate/customize Rails applications.
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* How to write your own reusable application templates using the Rails template API.
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--------------------------------------------------------------------------------
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Usage
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-----
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To apply a template, you need to provide the Rails generator with the location of the template you wish to apply using the -m option. This can either be a path to a file or a URL.
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```bash
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$ rails new blog -m ~/template.rb
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$ rails new blog -m http://example.com/template.rb
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```
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You can use the rake task `rails:template` to apply templates to an existing Rails application. The location of the template needs to be passed in to an environment variable named LOCATION. Again, this can either be path to a file or a URL.
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```bash
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$ bin/rake rails:template LOCATION=~/template.rb
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$ bin/rake rails:template LOCATION=http://example.com/template.rb
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```
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Template API
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------------
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The Rails templates API is easy to understand. Here's an example of a typical Rails template:
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```ruby
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# template.rb
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generate(:scaffold, "person name:string")
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route "root to: 'people#index'"
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rake("db:migrate")
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after_bundle do
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git :init
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git add: "."
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git commit: %Q{ -m 'Initial commit' }
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end
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```
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The following sections outline the primary methods provided by the API:
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### gem(*args)
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Adds a `gem` entry for the supplied gem to the generated application's `Gemfile`.
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For example, if your application depends on the gems `bj` and `nokogiri`:
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```ruby
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gem "bj"
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gem "nokogiri"
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```
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Please note that this will NOT install the gems for you and you will have to run `bundle install` to do that.
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```bash
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bundle install
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```
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### gem_group(*names, &block)
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Wraps gem entries inside a group.
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For example, if you want to load `rspec-rails` only in the `development` and `test` groups:
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```ruby
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gem_group :development, :test do
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gem "rspec-rails"
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end
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```
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### add_source(source, options = {})
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Adds the given source to the generated application's `Gemfile`.
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For example, if you need to source a gem from `"http://code.whytheluckystiff.net"`:
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```ruby
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add_source "http://code.whytheluckystiff.net"
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```
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### environment/application(data=nil, options={}, &block)
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Adds a line inside the `Application` class for `config/application.rb`.
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If `options[:env]` is specified, the line is appended to the corresponding file in `config/environments`.
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```ruby
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environment 'config.action_mailer.default_url_options = {host: "http://yourwebsite.example.com"}', env: 'production'
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```
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A block can be used in place of the `data` argument.
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### vendor/lib/file/initializer(filename, data = nil, &block)
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Adds an initializer to the generated application's `config/initializers` directory.
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Let's say you like using `Object#not_nil?` and `Object#not_blank?`:
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```ruby
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initializer 'bloatlol.rb', <<-CODE
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class Object
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def not_nil?
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!nil?
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end
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def not_blank?
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!blank?
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end
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end
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CODE
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```
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Similarly, `lib()` creates a file in the `lib/` directory and `vendor()` creates a file in the `vendor/` directory.
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There is even `file()`, which accepts a relative path from `Rails.root` and creates all the directories/files needed:
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```ruby
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file 'app/components/foo.rb', <<-CODE
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class Foo
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end
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CODE
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```
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That'll create the `app/components` directory and put `foo.rb` in there.
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### rakefile(filename, data = nil, &block)
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Creates a new rake file under `lib/tasks` with the supplied tasks:
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```ruby
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rakefile("bootstrap.rake") do
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<<-TASK
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namespace :boot do
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task :strap do
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puts "i like boots!"
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end
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end
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TASK
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end
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```
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The above creates `lib/tasks/bootstrap.rake` with a `boot:strap` rake task.
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### generate(what, *args)
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Runs the supplied rails generator with given arguments.
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```ruby
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generate(:scaffold, "person", "name:string", "address:text", "age:number")
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```
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### run(command)
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Executes an arbitrary command. Just like the backticks. Let's say you want to remove the `README.rdoc` file:
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```ruby
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run "rm README.rdoc"
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```
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### rake(command, options = {})
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Runs the supplied rake tasks in the Rails application. Let's say you want to migrate the database:
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```ruby
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rake "db:migrate"
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```
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You can also run rake tasks with a different Rails environment:
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```ruby
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rake "db:migrate", env: 'production'
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```
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### route(routing_code)
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Adds a routing entry to the `config/routes.rb` file. In the steps above, we generated a person scaffold and also removed `README.rdoc`. Now, to make `PeopleController#index` the default page for the application:
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```ruby
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route "root to: 'person#index'"
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```
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### inside(dir)
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Enables you to run a command from the given directory. For example, if you have a copy of edge rails that you wish to symlink from your new apps, you can do this:
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```ruby
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inside('vendor') do
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run "ln -s ~/commit-rails/rails rails"
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end
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```
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### ask(question)
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`ask()` gives you a chance to get some feedback from the user and use it in your templates. Let's say you want your user to name the new shiny library you're adding:
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```ruby
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lib_name = ask("What do you want to call the shiny library ?")
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lib_name << ".rb" unless lib_name.index(".rb")
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lib lib_name, <<-CODE
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class Shiny
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end
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CODE
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```
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### yes?(question) or no?(question)
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These methods let you ask questions from templates and decide the flow based on the user's answer. Let's say you want to freeze rails only if the user wants to:
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```ruby
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rake("rails:freeze:gems") if yes?("Freeze rails gems?")
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# no?(question) acts just the opposite.
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```
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### git(:command)
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Rails templates let you run any git command:
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```ruby
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git :init
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git add: "."
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git commit: "-a -m 'Initial commit'"
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```
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### after_bundle(&block)
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Registers a callback to be executed after the gems are bundled and binstubs
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are generated. Useful for all generated files to version control:
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```ruby
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after_bundle do
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git :init
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git add: '.'
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git commit: "-a -m 'Initial commit'"
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end
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```
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The callbacks gets executed even if `--skip-bundle` and/or `--skip-spring` has
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been passed.
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Advanced Usage
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--------------
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The application template is evaluated in the context of a
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`Rails::Generators::AppGenerator` instance. It uses the `apply` action
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provided by
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[Thor](https://github.com/erikhuda/thor/blob/master/lib/thor/actions.rb#L207).
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This means you can extend and change the instance to match your needs.
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For example by overwriting the `source_paths` method to contain the
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location of your template. Now methods like `copy_file` will accept
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relative paths to your template's location.
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```ruby
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def source_paths
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[File.expand_path(File.dirname(__FILE__))]
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end
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```
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