form_for seems to ignore any 'extra' attributes like a data-foo attribute or class passed as options in its second argument.
= form_for @user, {:url => 'foo', :class => 'x', 'data-bar' => 'baz' } do |f|
# ...
The output is a <form> tag with no x class or data-bar attribute.
What’s the fix?
Or, how can I grab a FormBuilder instance without using form_for?
Use the :html hash:
= form_for @user, :html => {:class => 'x', 'data-bar' => 'baz'} do |f|
Or
= form_for @user, html: {class: 'x', data: { bar: 'baz' } } do |f|
= form_for @user, :html => {'class' => 'x'} do |f|. class should be a symbol instead of string.Rails 4.0.3, Ruby 2.1.0p0 -> this worked for me =>
<%= form_for(@contact, :html => {:class => 'form_height'}) do |f| %><% if @contact.errors.any? %>
I had the same problem but was puzzled that another form elsewhere in my app was working fine.
I realized that I had accidentally added a form_for inside another form_for which once removed cured the problem.
Secondly, I should add that this syntax works for me in Rails 4.2:
<%= form_for @type, html: {class: "form-horizontal"} do |f| %>
I find it preferable to the punctuation-soup of the other answers here (which were perhaps based on an older Rails version).
On mostly helpers, the last arg is a hash of html options for the element.
= form_for @user, :html => {:class => 'x', 'data-bar' => 'baz'} %>
You can also check other alternatives in the documentation ActionsView::Helpers::FormHelper
I tried the above with no luck but found a solution. I'm using rails 4.1.6.
This didn't work
= form_for @user, :html => {:class => 'x', 'data-bar' => 'baz'} %>
This did
= form_for @user, html: {:class => 'x', 'data-bar' => 'baz'} %>
notice the difference with the html option, hope this helps
= form_for(:user, :url => login_path, html: {:class => 'login_form'}) do |f| %> This was the only way that my code would apply the class, otherwise it was just ignoring it.