问题
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?
回答1:
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|
回答2:
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? %>
回答3:
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).
回答4:
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
回答5:
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
来源：https://stackoverflow.com/questions/13144624/use-rails-form-for-but-set-custom-classes-attributes-on-form-element