Jump To Content

Calling partials through helpers

Rails partials are are fragments of template code that can be inserted into a view. They can really simplify template code, by factoring out repeated code.

For example, I often put forms into a partial so that the form can be shared be create and edit views:

quizzes/new.html.haml 
= error_messages_for :quiz
- form_for :quiz, @quiz, :url => quizzes_path, :html => {:method => :post} do |form|
  = render :partial => 'quizzes/form', :locals => {:form => form}
  = submit_tag 'Create'
quizzes/edit.html.haml 
= error_messages_for :quiz
- form_for :quiz, @quiz, :url => quiz_path(@quiz), :html => {:method => :put} do |form|
  = render :partial => 'quizzes/form', :locals => {:form => form}
  = submit_tag 'Update'

Many (most) people put the render call directly in their templates. This is not a good idea! What if you want to change the template path, or conditionally render a different template in certain conditions? Now you’ve got to repeat yourself in both templates, and that’s bad news.

A simple way to fix this is to always use a helper to render the partial. That way any changes can be made in one place, and it also a great place to store any messy conditional logic so that it doesn’t clutter up your templates.

quizzes/new.html.haml 
= error_messages_for :quiz
- form_for :quiz, @quiz, :url => quizzes_path, :html => {:method => :post} do |form|
  = quiz_form(form)
  = submit_tag 'Create'
quizzes/edit.html.haml 
= error_messages_for :quiz
- form_for :quiz, @quiz, :url => quiz_path(@quiz), :html => {:method => :put} do |form|
  = quiz_form(form)
  = submit_tag 'Update
quizzes_helper.rb 
def quiz_form(form)
   render :partial => 'quizzes/form', :locals => {:form => form}
end

Now if I want to do something, like say render a different form depending on a user’s preference, it’s easy to do.

quizzes/new.html.haml 
= error_messages_for :quiz
- form_for :quiz, @quiz, :url => quizzes_path, :html => {:method => :post} do |form|
  = quiz_form(form, current_user)
  = submit_tag 'Create'
quizzes_helper.rb 
def quiz_form(form, user = nil)
   if(!user.nil? && user.wants_advanced_quizzes))
     render :partial => 'quizzes/advanced_form', :locals => {:form => form}
   else
     render :partial => 'quizzes/form', :locals => {:form => form}
   end
end
  • Your comment will be modifiable for 10 minutes after posted.

Page Author

Avatar
wmoxam
Name
wmoxam

From Here You Can…

Information

Most Recent Related Content

Published In…

Creative Commons License
This work is licensed under a Creative Commons Attribution-Share Alike 3.0 Unported License.