Rails: How to pass a url path to a form_for partial in Rails?

Question

I'm trying to pass a url and variable to a form partial in Rails.

---

Method #1:
This works, but I'd rather not hardcode post_create_path into the form, so that it can be used for #update as well.

new.html.erb

<%= render partial: 'shared/form', locals: { form: @form } %>

_form.html.erb

<%= form_for form, url: post_create_path do |f| %>
...
<% end %>

---

Method #2:
This does not work.

new.html.erb

<%= render partial: 'shared/form', locals: { form: @form, url: post_create_path } %>

_form.html.erb

<%= form_for form, url: url do |f| %>
...
<% end %>

Error:

undefined local variable or method `url' for #<#:0x007f8d4d831fd0>

What I've also tried:

1. Just url instead of url:url but getting the same error.
2. Following this thread: How to pass url to partial/form?

I've been trying to make this work for a couple hours now and feel like I'm running out of options to try. Any help in pointing out what I'm doing wrong would be super appreciated!

Answer 1

you can use different actions by opening form_for on edit and new view templates and then pass the form object to the partial which contains all the fields of the form that are common to both create and update

new.html.erb

<%= form_for @post, :url => { :action => "create" } do |form| %>
  <%= render partial: 'shared/form', locals: { f: form } %>

edit.html.erb

<%= form_for @post, :url => { :action => "update" } do |form| %>
  <%= render partial: 'shared/form', locals: { f: form } %>

shared/_form.html.erb

  <%= f.text_field :title %>
  ...
  <%= f.submit "Save" %>
<% end %>

Answer 2

Use the locals hash as a form_for argument:

# new.html.erb
<%= render partial: 'shared/form', form: @form, locals: { url: post_create_path, method: :post} %>

# edit.html.erb
<%= render partial: 'shared/form', form: @form, locals: { url: post_update_path, method: :put} %>

# _form.html.erb
<%= form_for form, locals do |f| %>
...
<% end %>

locals is just a hash and you can give it any name (like vars). Then use it consistently in the views and the form.