Rails 3 Edit Multiple Records in a Single Form

Question

I've been stuck on this problem for a couple of days now.

I've have some success with Railscasts Episode #198, but that one is for Rails 2. There have been some changes in Rails 3 that make it so the code provided in Episode #198 won't work.

The problem lies within the edit_individual.html.erb:

Original Code (provided by Ryan @ Railscasts):

<% form_tag update_individual_products_path, :method => :put do %>
  <% for product in @products %>
    <% fields_for "products[]", product do |f| %>
      <h2><%=h product.name %></h2>
      <%= render "fields", :f => f %>
    <% end %>
  <% end %>
  <p><%= submit_tag "Submit" %></p>
<% end %>

Modified Code (simply changed fields_for to form_for):

<% form_tag update_individual_products_path, :method => :put do %>
  <% for product in @products %>
    <% form_for "products[]", product do |f| %>
      <h2><%=h product.name %></h2>
      <%= render "fields", :f => f %>
    <% end %>
  <% end %>
  <p><%= submit_tag "Submit" %></p>
<% end %>

In the new code, each record is placed within a form of their own, all inside one single form (which is the one I only want).

My question is, how can I get the code provided by Railscasts Episode #198 to work in Rails 3?

Here is a link to the Railscast I mentioned: http://railscasts.com/episodes/198-edit-multiple-individually

Thank You, c.allen.rosario

You cannot use `form_for` inside another `form_for` because that would mean a `
` tag inside another `
` tag. You **do** need to use `fields_for`. What are the errors when you run the code in Rails 3 ? — Zabba, Dec 08 '10 at 22:04
No errors are displayed. I just get a blank page with a submit button. — chris__allen, Dec 08 '10 at 23:58

score 19 · Accepted Answer · answered Dec 09 '10 at 00:13

19

I found the solution. Just need to modify the following line in the code provided by Ryan @ Railscasts:

<% fields_for "products[]", product do |f| %>

and change it to:

<%= fields_for "products[]", product do |f| %>

Notice, that the <% has been modified to <%=.

final solution:

<% form_tag update_individual_products_path :method => :put do %>  
  <% for product in @products %>  
    <%= fields_for "products[]", product do |f| %>  
      <h2><%= h product.name %></h2>  
    <% end %>  
  <% end %>  
  <p><%= submit_tag "Submit" %></p>  
<% end %>

I was wondering if anyone could explain this solution to me. From what I understand you should only need a <% in front of the fields_for.

c.allen.rosario

answered Dec 09 '10 at 00:13

chris__allen

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Yes, that `=` is required in Rails 3, though it was not required in earlier Rails versions. Did you not need to use it for the `form_tag` ? – Zabba Dec 09 '10 at 00:27
The = was not required for the form_tag – chris__allen Dec 09 '10 at 00:35
I think a comma is missing, your final solution should start with: `<% form_tag update_individual_products_path, :method => :put do %>` – Spone Jul 15 '16 at 18:15
For clarification: <%= is used if you expect some output to be written to the DOM (like a form tag, or an input field etc) whereas <% is used for situations where no output is expected (e.g. logic like <% if %>...<% end %>). This is the standard since rails 3 – randmin Mar 19 '20 at 17:24

score 4 · Answer 2 · answered Mar 17 '11 at 06:52

The change in Rails 3 from <% fields_for to <%= fields_for is because it was confusing that form_for, form_tag, etc... were using <% form... %> even though they they were outputting html code. With Rails 3, since they output html code, they use <%=.

Please note that your first line is deprecated:

<% form_tag update_individual_products_path, :method => :put do %>

should be

<%= form_tag update_individual_products_path, :method => :put do %>

Same for all form tags.

Rails 3 Edit Multiple Records in a Single Form

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