h2. Rails Application Templates Application templates are simple Ruby files containing DSL for adding gems/initializers etc. to your freshly created Rails project or an existing Rails project. By referring to this guide, you will be able to: * Use templates to generate/customize Rails applications * Write your own reusable application templates using the Rails template API endprologue. h3. Usage To apply a template, you need to provide the Rails generator with the location of the template you wish to apply, using -m option. This can either be path to a file or a URL. <shell> $ rails new blog -m ~/template.rb $ rails new blog -m http://example.com/template.rb </shell> 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. <shell> $ rake rails:template LOCATION=~/template.rb $ rake rails:template LOCATION=http://example.com/template.rb </shell> h3. Template API Rails templates API is very self explanatory and easy to understand. Here's an example of a typical Rails template: <ruby> # template.rb run "rm public/index.html" generate(:scaffold, "person name:string") route "root :to => 'people#index'" rake("db:migrate") git :init git :add => "." git :commit => "-a -m 'Initial commit'" </ruby> The following sections outlines the primary methods provided by the API: h4. gem(name, options = {}) Adds a +gem+ entry for the supplied gem to the generated application’s +Gemfile+. For example, if your application depends on the gems +bj+ and +nokogiri+: <ruby> gem "bj" gem "nokogiri" </ruby> Please note that this will NOT install the gems for you and you will have to run +bundle install+ to do that. <ruby> bundle install </ruby> h4. gem_group(*names, &block) Wraps gem entries inside a group. For example, if you want to load +rspec-rails+ only in +development+ and +test+ group: <ruby> gem_group :development, :test do gem "rspec-rails" end </ruby> h4. add_source(source, options = {}) Adds the given source to the generated application's +Gemfile+. For example, if you need to source a gem from "http://code.whytheluckystiff.net": <ruby> add_source "http://code.whytheluckystiff.net" </ruby> h4. vendor/lib/file/initializer(filename, data = nil, &block) Adds an initializer to the generated application’s +config/initializers+ directory. Lets say you like using +Object#not_nil?+ and +Object#not_blank?+: <ruby> initializer 'bloatlol.rb', <<-CODE class Object def not_nil? !nil? end def not_blank? !blank? end end CODE </ruby> Similarly +lib()+ creates a file in the +lib/+ directory and +vendor()+ creates a file in the +vendor/+ directory. There is even +file()+, which accepts a relative path from +Rails.root+ and creates all the directories/file needed: <ruby> file 'app/components/foo.rb', <<-CODE class Foo end CODE </ruby> That’ll create +app/components+ directory and put +foo.rb+ in there. h4. rakefile(filename, data = nil, &block) Creates a new rake file under +lib/tasks+ with the supplied tasks: <ruby> rakefile("bootstrap.rake") do <<-TASK namespace :boot do task :strap do puts "i like boots!" end end TASK end </ruby> The above creates +lib/tasks/bootstrap.rake+ with a +boot:strap+ rake task. h4. generate(what, args) Runs the supplied rails generator with given arguments. <ruby> generate(:scaffold, "person", "name:string", "address:text", "age:number") </ruby> h4. run(command) Executes an arbitrary command. Just like the backticks. Let's say you want to remove the +public/index.html+ file: <ruby> run "rm public/index.html" </ruby> h4. rake(command, options = {}) Runs the supplied rake tasks in the Rails application. Let's say you want to migrate the database: <ruby> rake "db:migrate" </ruby> You can also run rake tasks with a different Rails environment: <ruby> rake "db:migrate", :env => 'production' </ruby> h4. route(routing_code) This adds a routing entry to the +config/routes.rb+ file. In above steps, we generated a person scaffold and also removed +public/index.html+. Now to make +PeopleController#index+ as the default page for the application: <ruby> route "root :to => 'person#index'" </ruby> h4. inside(dir) 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: <ruby> inside('vendor') do run "ln -s ~/commit-rails/rails rails" end </ruby> h4. ask(question) +ask()+ gives you a chance to get some feedback from the user and use it in your templates. Lets say you want your user to name the new shiny library you’re adding: <ruby> lib_name = ask("What do you want to call the shiny library ?") lib_name << ".rb" unless lib_name.index(".rb") lib lib_name, <<-CODE class Shiny end CODE </ruby> h4. yes?(question) or no?(question) These methods let you ask questions from templates and decide the flow based on the user’s answer. Lets say you want to freeze rails only if the user want to: <ruby> rake("rails:freeze:gems") if yes?("Freeze rails gems ?") no?(question) acts just the opposite. </ruby> h4. git(:command) Rails templates let you run any git command: <ruby> git :init git :add => "." git :commit => "-a -m 'Initial commit'" </ruby>