CODEWITHSUNDEEP
rubyruby-on-rails-4
Shane
Shane

Reputation: 5677

How does form_for generate paths in rails?

Can anyone explain me on how the paths are generated using form_for?. The below code generates a path article_comments_path.

<%= form_for [@article, @comment] do |f| %>    
<% end %>

I mean how does it exactly generate article_comments_path and not articles_comment_path

Upvotes: 1

Views: 142

Answers (1)

BroiSatse
BroiSatse

Reputation: 44715

It is using polymorphic_path method to determine the path. It is basicaly a wrpaper around polymorphic_url: http://apidock.com/rails/v4.0.2/ActionDispatch/Routing/PolymorphicRoutes/polymorphic_url

Update:

polymorphic_path is using internally method called build_named_route_call. When it gets an array, it pull the last record out of the array (with pop) and then iterates over the remaining array, changing all the objects to

  1. if it is a model it takes it class and calls `model_name.singular_route_key'
  2. if it is a symbol or string, leaves it as it is

Then we are left with the last element. It can be singular or plural, this is resolved in polymorphic_url method with this case statement:

inflection = if options[:action] && options[:action].to_s == "new"
      args.pop
      :singular
    elsif (record.respond_to?(:persisted?) && !record.persisted?)
      args.pop
      :plural
    elsif record.is_a?(Class)
      args.pop
      :plural
    else
      :singular
    end

where record is a first element of the array (if array is passed). inlection var is then passed to build_named_route_call so it can build correct helper name. As you can see this form will generate different paths depending on whether the first element is already persisted or not.

Upvotes: 2

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