Method: ActionView::Helpers::FormBuilder#field_id

Defined in:

actionview/lib/action_view/helpers/form_helper.rb

#field_id(method, *suffixes, namespace: , index: ) ⇒ Object

Generate an HTML id attribute value for the given field

Return the value generated by the FormBuilder for the given attribute name.

<%= form_with model: @article do |f| %>
  <%= f.label :title %>
  <%= f.text_field :title, aria: { describedby: f.field_id(:title, :error) } %>
  <%= tag.span("is blank", id: f.field_id(:title, :error) %>
<% end %>

In the example above, the <input type="text"> element built by the call to FormBuilder#text_field declares an aria-describedby attribute referencing the <span> element, sharing a common id root (article_title, in this case).

# File 'actionview/lib/action_view/helpers/form_helper.rb', line 1777

def field_id(method, *suffixes, namespace: @options[:namespace], index: @options[:index])
  @template.field_id(@object_name, method, *suffixes, namespace: namespace, index: index)
end