h2. Rails Application Templates
Application templates are simple ruby files containing DSL for adding plugins/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 :
<shell>
$ rails blog -m ~/template.rb
</shell>
It's also possible to apply a template using a URL :
<shell>
$ rails blog -m http://gist.github.com/31208.txt
</shell>
Alternatively, you can use the rake task +rails:template+ to apply a template to an existing Rails application :
<shell>
$ rake rails:template LOCATION=~/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 "map.root :controller => 'people'"
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 +config.gem+ entry for the supplied gem to the generated application’s +config/environment.rb+.
For example, if your application depends on the gems +bj+ and +hpricot+ :
<ruby>
gem "bj"
gem "hpricot", :version => '0.6', :source => "http://code.whytheluckystiff.net"
</ruby>
Please note that this will NOT install the gems for you. So you may want to run the +rake gems:install+ task too :
<ruby>
rake "gems:install"
</ruby>
And let Rails take care of installing the required gems if they’re not already installed.
h4. plugin(name, options = {})
Installs a plugin to the generated application.
Plugin can be installed from Git :
<ruby>
plugin 'authentication', :git => 'git://github.com/foor/bar.git'
</ruby>
You can even install plugins as git submodules :
<ruby>
plugin 'authentication', :git => 'git://github.com/foor/bar.git',
:submodule => true
</ruby>
Please note that you need to +git :init+ before you can install a plugin as a submodule.
Or use plain old SVN :
<ruby>
plugin 'usingsvn', :svn => 'svn://example.com/usingsvn/trunk'
</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. For example, I love to scaffold some whenever I’m playing with Rails :
<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>
Or even use sudo :
<ruby>
rake "gems:install", :sudo => true
</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 "map.root :controller => :person"
</ruby>
h4. inside(dir)
I have my edge rails lying at +~/commit-rails/rails+. So every time i have to manually symlink edge from my new app. But now :
<ruby>
inside('vendor') do
run "ln -s ~/commit-rails/rails rails"
end
</ruby>
So +inside()+ runs the command from the given directory.
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(:must => "-a love")
Rails templates let you run any git command :
<ruby>
git :init
git :add => "."
git :commit => "-a -m 'Initial commit'"
</ruby>
h3. Changelog
"Lighthouse ticket":http://rails.lighthouseapp.com/projects/16213-rails-guides/tickets/78
* April 29, 2009: Initial version by "Pratik":credits.html#lifo
