Application Helpers

Form Builders

Form builders are full-featured objects allowing the construction of complex object-based forms using a simple, intuitive syntax.

A form_for using these basic fields might look like:

= form_for @user, '/register', id: 'register' do |f|
  = f.error_messages
  %p
    = f.label :username, caption: "Nickname"
    = f.text_field :username
  %p
    = f.label :email
    = f.text_field :email
  %p
    = f.label :password
    = f.password_field :password
  %p
    = f.label :is_admin, caption: "Admin User?"
    = f.check_box :is_admin
  %p
    = f.label :color, caption: "Favorite Color?"
    = f.select :color, options: ['red', 'black']
  %p
    = fields_for @user.location do |location|
      = location.text_field :street
      = location.text_field :city
  %p
    = f.submit 'Create', class: 'button'

Form Builder Helpers

• form_for(object, url, settings = {}, &block)
  • Constructs a form using given or default form_builder
  • Supports form methods 'put' and 'delete' through hidden field
  • Defaults to StandardFormBuilder but you can easily create your own!
  • form_for(@user, '/register', id: 'register') { |f| ...field-elements... }
  • form_for(:user, '/register', id: 'register') { |f| ...field-elements... }
• fields_for(object, settings = {}, &block)
  • Constructs fields for a given object for use in an existing form
  • Defaults to StandardFormBuilder but you can easily create your own!
  • fields_for @user.assignment do |assignment| ... end
  • fields_for :assignment do |assignment| ... end

Some of the methods provided by AbstractFormBuilder that can be used within form_for or fields_for are:

• error_messages(options = {})
  • Displays list html for the errors on form object
  • f.error_messages
• label(field, options = {})
  • f.label :name, class: 'long'
• text_field(field, options = {})
  • f.text_field :username, class: 'long'
• check_box(field, options = {})
  • Uses hidden field to provide a 'unchecked' value for field
  • f.check_box :remember_me, uncheck_value: 'false'
• radio_button(field, options = {})
  • f.radio_button :gender, value: 'male'
• hidden_field(field, options = {})
  • f.hidden_field :session_id, class: 'hidden'
• text_area(field, options = {})
  • f.text_area :summary, class: 'long'
• password_field(field, options = {})
  • f.password_field :secret, class: 'long'
• number_field(field, options = {})
  • f.number_field :age, class: 'long'
• telephone_field(field, options = {})
  • f.telephone_field :mobile, class: 'long'
• email_field(field, options = {})
  • f.email_field :email, class: 'long'
• search_field(field, options = {})
  • f.search_field :query, class: 'long'
• url_field(field, options = {})
  • f.url_field :image_source, class: 'long'
• file_field(field, options = {})
  • f.file_field :photo, class: 'long'
• select(field, options = {})
  • f.select(:state, options: ['California', 'Texas', 'Wyoming'])
  • f.select(:state, collection: @states, fields: [:name, :id])
  • f.select(:state, options: [...], include_blank: true)
• submit(caption, options = {})
  • f.submit 'Update', class: 'long'
• image_submit(source, options = {})
  • f.image_submit 'submit.png', class: 'long'
• date_field(field, options = {})
  • f.date_field :time_start, class: 'input'

For a complete list checkout the form helper docs.

Localization

See localization.

last updated: 2025-12-02