See the "Namespaced forms all multiple Formtastic forms to exist on the one page without DOM id clashes and invalid HTML documents." in the documentation of semantic_form_for.

That should solve your problem.

@mikz thank's for your reply, i placed the namespace and did not solve.

@dcalixto you can still pass :html option to it. So something like this would solve your problem:

semantic_form_for(@user, html: { id: 'prefixed_form' })

thank you very much @mikz , and unintentionally abuse, the same probem seems to appear on submit:

i've tried the same logic but seems not solve.

Duplicate ID "user_submit_action"

  <%= form.actions do %>
        <%= form.action(:submit, :label => "Save",  :button_html => { :class => "btn", id: 'button_address'}) %>
        <% end %>

@dcalixto could you post the generated html ? It is weird, that button_html would not work.

@dcalixto I check the source and the tests and I don't see any possibility why :namespace option should not work. Could you paste an example how you were trying to use it?

It would help us a lot. To improve documentation, we need to learn how people use it and what mistakes they make.

I too am experiencing the same problem with the namespace option. The versions used are: formtastic (3.1.4) and formtastic-bootstrap (3.1.1). (I wonder if it's a formtastic-bootstrap problem.)

Using the plain old Rails form builder:

= form_for(@animal, namespace: 'cat', url: zookeeper_animal_path) do |f|

gets me:

<form id="cat_edit_zoo_animal_249" class="edit_zoo_animal" method="post" accept-charset="UTF-8" action="/zookeeper/animals/249">

whereas using Formtastic:

= semantic_form_for(@animal, namespace: 'cat', url: zookeeper_animal_path) do |f|

gets me:

<form id="edit_zoo_animal_249" class="formtastic zoo_animal" method="post" accept-charset="UTF-8" action="/zookeeper/animals/249" novalidate="novalidate">

So the cat namespace is missing in the id.

Note that in this example, the ActiveRecord model is class Zoo::Animal but the controller I am posting to is class Zookeeper::Animal so there is some Ruby namespacing going on.

@fredngo Thanks for the report! I made a PR (#1212) with a regression test to verify it surely fails. And it does.

I'm not sure why, how to fix it or how much time I'll have to work on that. If you feel like, feel free to chip in.

Wow, thanks for the quick response @mikz ! For now that the issue is documented at least.

I'm experiencing the same problem with duplicate ids on the submit buttons and forms.

I think this is happening because the :namespace option isn't being passed to the original implementation of form_for. It gets remapped as custom_namespace.

@mikz Do you know if there's a reason it was remapped like this?

I made #1065 to fix #904. It was doing nasty stuff and changing class variables when rendering forms.

It is possible I did not fully understand the implications and it has a bug that prevents using the :namespace option. We should verify the regression test #1212 failed/passed before these changes. If so then it indeed broke it.

@justinfrench #1212 doesn't seem to be merged yet; did some other fix solve this bug?

@fredngo I closed this as part of a mass clean-up. If you have the time to pull all this together in one PR, I'd really appreciate the help, as I don't have the time to maintain this like I used to.