Notes posted by rubymaverick

How I use Optimistic Locking

I have used Optimistic locking often, but usually I only need it in one or two places in the codebase, not everywhere an object is saved whose model has a lock_version column. So what I usually end up doing is using a little module I wrote called OptimisticallyLockable (awesome name right?). Here it is:

module OptimisticallyLockable

  def self.included(receiver)
    receiver.lock_optimistically = false
    receiver.class_eval do

      def self.with_optimistic_locking
        original_lock = self.lock_optimistically
        self.lock_optimistically = true

        begin
          yield
        ensure
          self.lock_optimistically = original_lock
        end
      end

    end
  end

end

When included in a model that has a lock_version column it will turn off optimistic locking. Then when you want to actually use optimistic locking you can just use the with_optimistic_locking method like this:

class Blog
   include OptimisticallyLockable

   def do_something_destructive!
     self.class.with_optimistic_locking do
        #  do something important here
     end
   end                                
end

Turn layout off

If you don’t want a layout rendered, just put:

layout nil

in your controller.

Rails defined Mime Types

Here are all the default Rails Mime Types:

"*/*"                      => :all
"text/plain"               => :text
"text/html"                => :html 
"application/xhtml+xml"    => :html
"text/javascript"          => :js 
"application/javascript"   => :js 
"application/x-javascript" => :js 
"text/calendar"            => :ics   
"text/csv"                 => :csv   
"application/xml"          => :xml 
"text/xml"                 => :xml 
"application/x-xml"        => :xml 
"text/yaml"                => :yaml 
"application/x-yaml"       => :yaml 
"application/rss+xml"      => :rss   
"application/atom+xml"     => :atom  
"application/json"         => :json 
"text/x-json"              => :json

Default Mime Types

This module sets up all the default mime-types. Here they are:

"*/*"                      => :all
"text/plain"               => :text
"text/html"                => :html 
"application/xhtml+xml"    => :html
"text/javascript"          => :js 
"application/javascript"   => :js 
"application/x-javascript" => :js 
"text/calendar"            => :ics   
"text/csv"                 => :csv   
"application/xml"          => :xml 
"text/xml"                 => :xml 
"application/x-xml"        => :xml 
"text/yaml"                => :yaml 
"application/x-yaml"       => :yaml 
"application/rss+xml"      => :rss   
"application/atom+xml"     => :atom  
"application/json"         => :json 
"text/x-json"              => :json

How to test different responses in controller tests/specs

When you want to write a controller test or spec (rspec) to test out a different response type other than html, just set the HTTP_ACCEPTS header like so before the request:

@request.env['HTTP_ACCEPT'] = "application/rss"
post :create, :blog => {}

Custom MIME Type

After you register a custom Mime::Type like stated above, you can do:

respond_to do |format|
  # .jpg corresponds to the second argument passed to #register
  # Mime::Type.register "image/jpg", :jpg
  format.jpg { ...do something here... }
end