How to get a form's id?

addis_a · August 5, 2014, 1:54am

I want to use a form’s id in javascript that runs after the DOM is
loaded, so what method would get the form’s id for an object? In other
words, there will be erb thus:

<%= form_for(@obj) do |f| %>…<% end %>

so what erb would give me the id which that form will get?

I know I can just give the form a custom id as a workaround, but I
really do not need to change the id, just know what it is. (I also can
calculate it myself pretty easily, but I’d rather use the same method
that RoR uses, for future-proofing.)

This is all a very small issue, given the multiple easy workarounds. I’m
just surprised that I could not find anything in the docs or forums.
(RoR 3.2, BTW.)

–
Scott R.
[email protected]
http://www.elevated-dev.com/
(303) 722-0567 voice

scottrutherford · August 5, 2014, 5:59am

Hi Scott, it is an interesting question. I was seeing in the source code
and I found that[0]. Basically, rails ask to object if it is persisted
or
not to create the id.
But this is a private method, then you should need to implement this
logic
in a helper(?) or something.

[0]

github.com

rails/rails/blob/7a085dac2a2820856cbe6c2ca8c69779ac766a97/actionview/lib/action_view/helpers/form_helper.rb#L440


      
            html_options[:method] = options.delete(:method) if options.has_key?(:method)
            html_options[:authenticity_token] = options.delete(:authenticity_token)
          
          
  builder = instantiate_builder(object_name, object, options)
            output  = capture(builder, &block)
            html_options[:multipart] ||= builder.multipart?
          
          
  form_tag(options[:url] || {}, html_options) { output }
          end
          
          
def apply_form_for_options!(record, object, options) #:nodoc:
            object = convert_to_model(object)
          
          
  as = options[:as]
            namespace = options[:namespace]
            action, method = object.respond_to?(:persisted?) && object.persisted? ? [:edit, :patch] : [:new, :post]
            options[:html].reverse_merge!(
              class:  as ? "#{action}_#{as}" : dom_class(object, action),
              id:     (as ? [namespace, action, as] : [namespace, dom_id(object, action)]).compact.join("_").presence,
              method: method
            )

Matt’s

On Mon, Aug 4, 2014 at 7:53 PM, Scott R. [email protected]

scottrutherford · August 5, 2014, 2:32pm

On Aug 4, 2014, at 9:57 PM, Carlos M. [email protected]
wrote:

Hi Scott, it is an interesting question. I was seeing in the source code and I
found that[0]. Basically, rails ask to object if it is persisted or not to create
the id.
But this is a private method, then you should need to implement this logic in a
helper(?) or something.

Re-implementing would completely defeat the purpose of not using my own
id, so I’ll just use my own. Thanks for the pointer to the
implementation.

–
Scott R.
[email protected]
http://www.elevated-dev.com/
(303) 722-0567 voice