By Plataformatec.

Rails forms made easy.

Simple Form aims to be as flexible as possible while helping you with powerful components to create your forms. The basic goal of Simple Form is to not touch your way of defining the layout, letting you find the better design for your eyes. Most of the DSL was inherited from Formtastic, which we are thankful for and should make you feel right at home.

INFO: This README is also available in a friendly navigable format and refers to Simple Form 3.1. For older releases, check the related branch for your version.

Installation

Add it to your Gemfile:

gem 'simple_form'

Run the following command to install it:

bundle install

Run the generator:

rails generate simple_form:install

Bootstrap

Simple Form can be easily integrated to the Bootstrap. To do that you have to use the bootstrap option in the install generator, like this:

rails generate simple_form:install --bootstrap

You have to be sure that you added a copy of the Bootstrap assets on your application.

For more information see the generator output, our example application code and the live example app.

Zurb Foundation 5

To generate wrappers that are compatible with Zurb Foundation 5, pass the foundation option to the generator, like this:

rails generate simple_form:install --foundation

Please note that the Foundation wrapper does not support the :hint option by default. In order to enable hints, please uncomment the appropriate line in config/initializers/simple_form_foundation.rb. You will need to provide your own CSS styles for hints.

Please see the instructions on how to install Foundation in a Rails app.

Country Select

If you want to use the country select, you will need the country_select gem, add it to your Gemfile:

gem 'country_select'

If you don't want to use the gem you can easily override this behaviour by mapping the country inputs to something else, with a line like this in your simple_form.rb initializer:

config.input_mappings = { /country/ => :string }

Usage

Simple Form was designed to be customized as you need to. Basically it's a stack of components that are invoked to create a complete html input for you, which by default contains label, hints, errors and the input itself. It does not aim to create a lot of different logic from the default Rails form helpers, as they do a great job by themselves. Instead, Simple Form acts as a DSL and just maps your input type (retrieved from the column definition in the database) to a specific helper method.

To start using Simple Form you just have to use the helper it provides:

<%= simple_form_for @user do |f| %>
  <%= f.input :username %>
  <%= f.input :password %>
  <%= f.button :submit %>
<% end %>

This will generate an entire form with labels for user name and password as well, and render errors by default when you render the form with invalid data (after submitting for example).

You can overwrite the default label by passing it to the input method. You can also add a hint, an error, or even a placeholder. For boolean inputs, you can add an inline label as well:

<%= simple_form_for @user do |f| %>
  <%= f.input :username, label: 'Your username please', error: 'Username is mandatory, please specify one' %>
  <%= f.input :password, hint: 'No special characters.' %>
  <%= f.input :email, placeholder: 'user@domain.com' %>
  <%= f.input :remember_me, inline_label: 'Yes, remember me' %>
  <%= f.button :submit %>
<% end %>

In some cases you may want to disable labels, hints or errors. Or you may want to configure the html of any of them:

<%= simple_form_for @user do |f| %>
  <%= f.input :username, label_html: { class: 'my_class' } %>
  <%= f.input :password, hint: false, error_html: { id: 'password_error'} %>
  <%= f.input :password_confirmation, label: false %>
  <%= f.button :submit %>
<% end %>

It is also possible to pass any html attribute straight to the input, by using the :input_html option, for instance:

<%= simple_form_for @user do |f| %>
  <%= f.input :username, input_html: { class: 'special' } %>
  <%= f.input :password, input_html: { maxlength: 20 } %>
  <%= f.input :remember_me, input_html: { value: '1' } %>
  <%= f.button :submit %>
<% end %>

If you want to pass the same options to all inputs in the form (for example, a default class), you can use the :defaults option in simple_form_for. Specific options in input call will overwrite the defaults:

<%= simple_form_for @user, defaults: { input_html: { class: 'default_class' } } do |f| %>
  <%= f.input :username, input_html: { class: 'special' } %>
  <%= f.input :password, input_html: { maxlength: 20 } %>
  <%= f.input :remember_me, input_html: { value: '1' } %>
  <%= f.button :submit %>
<% end %>

Since Simple Form generates a wrapper div around your label and input by default, you can pass any html attribute to that wrapper as well using the :wrapper_html option, like so:

<%= simple_form_for @user do |f| %>
  <%= f.input :username, wrapper_html: { class: 'username' } %>
  <%= f.input :password, wrapper_html: { id: 'password' } %>
  <%= f.input :remember_me, wrapper_html: { class: 'options' } %>
  <%= f.button :submit %>
<% end %>

Required fields are marked with an * prepended to their labels.

By default all inputs are required. When the form object includes ActiveModel::Validations (which, for example, happens with Active Record models), fields are required only when there is presence validation. Otherwise, Simple Form will mark fields as optional. For performance reasons, this detection is skipped on validations that make use of conditional options, such as :if and :unless.

And of course, the required property of any input can be overwritten as needed:

<%= simple_form_for @user do |f| %>
  <%= f.input :name, required: false %>
  <%= f.input :username %>
  <%= f.input :password %>
  <%= f.button :submit %>
<% end %>

By default, Simple Form will look at the column type in the database and use an appropriate input for the column. For example, a column created with type :text in the database will use a textarea input by default. See the section Available input types and defaults for each column type for a complete list of defaults.

Simple Form also lets you overwrite the default input type it creates:

<%= simple_form_for @user do |f| %>
  <%= f.input :username %>
  <%= f.input :password %>
  <%= f.input :description, as: :text %>
  <%= f.input :accepts,     as: :radio_buttons %>
  <%= f.button :submit %>
<% end %>

So instead of a checkbox for the accepts attribute, you'll have a pair of radio buttons with yes/no labels and a textarea instead of a text field for the description. You can also render boolean attributes using as: :select to show a dropdown.

It is also possible to give the :disabled option to Simple Form, and it'll automatically mark the wrapper as disabled with a CSS class, so you can style labels, hints and other components inside the wrapper as well:

<%= simple_form_for @user do |f| %>
  <%= f.input :username, disabled: true, hint: 'You cannot change your username.' %>
  <%= f.button :submit %>
<% end %>

Simple Form inputs accept the same options as their corresponding input type helper in Rails:

<%= simple_form_for @user do |f| %>
  <%= f.input :date_of_birth, as: :date, start_year: Date.today.year - 90,
                              end_year: Date.today.year - 12, discard_day: true,
                              order: [:month, :year] %>
  <%= f.input :accepts, as: :boolean, checked_value: true, unchecked_value: false %>
  <%= f.button :submit %>
<% end %>

Simple Form also allows you to use label, hint, input_field, error and full_error helpers (please take a look at the rdocs for each method for more info):

<%= simple_form_for @user do |f| %>
  <%= f.label :username %>
  <%= f.input_field :username %>
  <%= f.hint 'No special characters, please!' %>
  <%= f.error :username, id: 'user_name_error' %>
  <%= f.full_error :token %>
  <%= f.submit 'Save' %>
<% end %>

Any extra option passed to these methods will be rendered as html option.

Stripping away all wrapper divs

Simple Form also allows you to strip away all the div wrappers around the <input> field that is generated with the usual f.input. The easiest way to achieve this is to use f.input_field.

Example:

simple_form_for @user do |f|
  f.input_field :name
  f.input_field :remember_me, as: :boolean
end

<form>
  ...
  <input class="string required" id="user_name" maxlength="255" name="user[name]" size="255" type="text">
  <input name="user[remember_me]" type="hidden" value="0">
  <label class="checkbox">
    <input class="boolean optional" id="user_published" name="user[remember_me]" type="checkbox" value="1">
  </label>
</form>

For check boxes and radio buttons you can remove the label changing boolean_style from default value :nested to :inline.

Example:

simple_form_for @user do |f|
  f.input_field :name
  f.input_field :remember_me, as: :boolean, boolean_style: :inline
end

<form>
  ...
  <input class="string required" id="user_name" maxlength="255" name="user[name]" size="255" type="text">
  <input name="user[remember_me]" type="hidden" value="0">
  <input class="boolean optional" id="user_remember_me" name="user[remember_me]" type="checkbox" value="1">
</form>

To view the actual RDocs for this, check them out here - http://rubydoc.info/github/plataformatec/simple_form/master/SimpleForm/FormBuilder:input_field

Collections

And what if you want to create a select containing the age from 18 to 60 in your form? You can do it overriding the :collection option:

<%= simple_form_for @user do |f| %>
  <%= f.input :user %>
  <%= f.input :age, collection: 18..60 %>
  <%= f.button :submit %>
<% end %>

Collections can be arrays or ranges, and when a :collection is given the :select input will be rendered by default, so we don't need to pass the as: :select option. Other types of collection are :radio_buttons and :check_boxes. Those are added by Simple Form to Rails set of form helpers (read Extra Helpers section below for more information).

Collection inputs accept two other options beside collections:

label_method => the label method to be applied to the collection to retrieve the label (use this instead of the text_method option in collection_select)
value_method => the value method to be applied to the collection to retrieve the value

Those methods are useful to manipulate the given collection. Both of these options also accept lambda/procs in case you want to calculate the value or label in a special way eg. custom translation. You can also define a to_label method on your model as Simple Form will search for and use :to_label as a :label_method first if it is found.

By default, Simple Form will use the first item from an array as the label and the second one as the value. If you want to change this behavior you must make it explicit, like this:

<%= simple_form_for @user do |f| %>
  <%= f.input :gender, as: :radio_buttons, collection: [['0', 'female'], ['1', 'male']], label_method: :second, value_method: :first %>
<% end %>

All other options given are sent straight to the underlying helper. For example, you can give prompt as:

f.input :age, collection: 18..60, prompt: "Select your age", selected: 21

Extra options are passed into helper collection_select.

You may also find it useful to explicitly pass a value to the optional :selected, especially if passing a collection of nested objects.

It is also possible to create grouped collection selects, that will use the html optgroup tags, like this:

f.input :country_id, collection: @continents, as: :grouped_select, group_method: :countries

Grouped collection inputs accept the same :label_method and :value_method options, which will be used to retrieve label/value attributes for the option tags. Besides that, you can give:

group_method => the method to be called on the given collection to generate the options for each group (required)
group_label_method => the label method to be applied on the given collection to retrieve the label for the optgroup (Simple Form will attempt to guess the best one the same way it does with :label_method)

Priority

Simple Form also supports :time_zone and :country. When using such helpers, you can give :priority as an option to select which time zones and/or countries should be given higher priority:

f.input :residence_country, priority: [ "Brazil" ]
f.input :time_zone, priority: /US/

Those values can also be configured with a default value to be used on the site through the SimpleForm.country_priority and SimpleForm.time_zone_priority helpers.

Note: While using country_select if you want to restrict to only a subset of countries for a specific drop down then you may use the :collection option:

f.input :shipping_country, priority: [ "Brazil" ], collection: [ "Australia", "Brazil", "New Zealand"]

Associations

To deal with associations, Simple Form can generate select inputs, a series of radios buttons or checkboxes. Lets see how it works: imagine you have a user model that belongs to a company and has_and_belongs_to_many roles. The structure would be something like:

class User < ActiveRecord::Base
  belongs_to :company
  has_and_belongs_to_many :roles
end

class Company < ActiveRecord::Base
  has_many :users
end

class Role < ActiveRecord::Base
  has_and_belongs_to_many :users
end

Now we have the user form:

<%= simple_form_for @user do |f| %>
  <%= f.input :name %>
  <%= f.association :company %>
  <%= f.association :roles %>
  <%= f.button :submit %>
<% end %>

Simple enough, right? This is going to render a :select input for choosing the :company, and another :select input with :multiple option for the :roles. You can, of course, change it to use radio buttons and checkboxes as well:

f.association :company, as: :radio_buttons
f.association :roles,   as: :check_boxes

The association helper just invokes input under the hood, so all options available to :select, :radio_buttons and :check_boxes are also available to association. Additionally, you can specify the collection by hand, all together with the prompt:

f.association :company, collection: Company.active.order(:name), prompt: "Choose a Company"

In case you want to declare different labels and values:

f.association :company, label_method: :company_name, value_method: :id, include_blank: false

Please note that the association helper is currently only tested with Active Record. It currently does not work well with Mongoid and depending on the ORM you're using your mileage may vary.

Buttons

All web forms need buttons, right? Simple Form wraps them in the DSL, acting like a proxy:

<%= simple_form_for @user do |f| %>
  <%= f.input :name %>
  <%= f.button :submit %>
<% end %>

The above will simply call submit. You choose to use it or not, it's just a question of taste.

The button method also accepts optional parameters, that are delegated to the underlying submit call:

<%= f.button :submit, "Custom Button Text", class: "my-button" %>

To create a <button> element, use the following syntax:

<%= f.button :button, "Custom Button Text" %>

<%= f.button :button do %>
  Custom Button Text
<% end %>

Wrapping Rails Form Helpers

Say you wanted to use a rails form helper but still wrap it in Simple Form goodness? You can, by calling input with a block like so:

<%= f.input :role do %>
  <%= f.select :role, Role.all.map { |r| [r.name, r.id, { class: r.company.id }] }, include_blank: true %>
<% end %>

In the above example, we're taking advantage of Rails 3's select method that allows us to pass in a hash of additional attributes for each option.

Extra helpers

Simple Form also comes with some extra helpers you can use inside rails default forms without relying on simple_form_for helper. They are listed below.

Simple Fields For

Wrapper to use Simple Form inside a default rails form. It works in the same way that the fields_for Rails helper, but change the builder to use the SimpleForm::FormBuilder.

form_for @user do |f|
  f.simple_fields_for :posts do |posts_form|
    # Here you have all simple_form methods available
    posts_form.input :title
  end
end

Collection Radio Buttons

Creates a collection of radio inputs with labels associated (same API as collection_select):

form_for @user do |f|
  f.collection_radio_buttons :options, [[true, 'Yes'], [false, 'No']], :first, :last
end

<input id="user_options_true" name="user[options]" type="radio" value="true" />
<label class="collection_radio_buttons" for="user_options_true">Yes</label>
<input id="user_options_false" name="user[options]" type="radio" value="false" />
<label class="collection_radio_buttons" for="user_options_false">No</label>

Collection Check Boxes

Creates a collection of checkboxes with labels associated (same API as collection_select):

form_for @user do |f|
  f.collection_check_boxes :options, [[true, 'Yes'], [false, 'No']], :first, :last
end

<input name="user[options][]" type="hidden" value="" />
<input id="user_options_true" name="user[options][]" type="checkbox" value="true" />
<label class="collection_check_box" for="user_options_true">Yes</label>
<input name="user[options][]" type="hidden" value="" />
<input id="user_options_false" name="user[options][]" type="checkbox" value="false" />
<label class="collection_check_box" for="user_options_false">No</label>

To use this with associations in your model, you can do the following:

form_for @user do |f|
  f.collection_check_boxes :role_ids, Role.all, :id, :name # using :roles here is not going to work.
end

To add a CSS class to the label item, you can use the item_label_class option:

f.collection_check_boxes :role_ids, Role.all, :id, :name, item_label_class: 'my-custom-class'

Available input types and defaults for each column type

The following table shows the html element you will get for each attribute according to its database definition. These defaults can be changed by specifying the helper method in the column Mapping as the as: option.

Mapping	Generated HTML Element	Database Column Type
`boolean`	`input[type=checkbox]`	`boolean`
`string`	`input[type=text]`	`string`
`citext`	`input[type=text]`	`citext`
`email`	`input[type=email]`	`string` with `name =~ /email/`
`url`	`input[type=url]`	`string` with `name =~ /url/`
`tel`	`input[type=tel]`	`string` with `name =~ /phone/`
`password`	`input[type=password]`	`string` with `name =~ /password/`
`search`	`input[type=search]`	-
`uuid`	`input[type=text]`	`uuid`
`text`	`textarea`	`text`
`hstore`	`textarea`	`hstore`
`json`	`textarea`	`json`
`jsonb`	`textarea`	`jsonb`
`file`	`input[type=file]`	`string` responding to file methods
`hidden`	`input[type=hidden]`	-
`integer`	`input[type=number]`	`integer`
`float`	`input[type=number]`	`float`
`decimal`	`input[type=number]`	`decimal`
`range`	`input[type=range]`	-
`datetime`	`datetime select`	`datetime/timestamp`
`date`	`date select`	`date`
`time`	`time select`	`time`
`select`	`select`	`belongs_to`/`has_many`/`has_and_belongs_to_many` associations
`radio_buttons`	collection of `input[type=radio]`	`belongs_to` associations
`check_boxes`	collection of `input[type=checkbox]`	`has_many`/`has_and_belongs_to_many` associations
`country`	`select` (countries as options)	`string` with `name =~ /country/`
`time_zone`	`select` (timezones as options)	`string` with `name =~ /time_zone/`

Custom inputs

It is very easy to add custom inputs to Simple Form. For instance, if you want to add a custom input that extends the string one, you just need to add this file:

# app/inputs/currency_input.rb
class CurrencyInput < SimpleForm::Inputs::Base
  def input(wrapper_options)
    merged_input_options = merge_wrapper_options(input_html_options, wrapper_options)

    "$ #{@builder.text_field(attribute_name, merged_input_options)}".html_safe
  end
end

And use it in your views:

f.input :money, as: :currency

Note, you may have to create the app/inputs/ directory and restart your webserver.

You can also redefine existing Simple Form inputs by creating a new class with the same name. For instance, if you want to wrap date/time/datetime in a div, you can do:

# app/inputs/date_time_input.rb
class DateTimeInput < SimpleForm::Inputs::DateTimeInput
  def input(wrapper_options)
    template.content_tag(:div, super)
  end
end

Or if you want to add a class to all the select fields you can do:

# app/inputs/collection_select_input.rb
class CollectionSelectInput < SimpleForm::Inputs::CollectionSelectInput
  def input_html_classes
    super.push('chosen')
  end
end

If needed, you can namespace your custom inputs in a module and tell Simple Form to look for their definitions in this module. This can avoid conflicts with other form libraries (like Formtastic) that look up the global context to find inputs definition too.

# app/inputs/custom_inputs/numeric_input
module CustomInputs
  class NumericInput < SimpleForm::Inputs::NumericInput
    def input_html_classes
      super.push('no-spinner')
    end
  end
end

And in the SimpleForm initializer :

# config/simple_form.rb
config.custom_inputs_namespaces << "CustomInputs"

Custom form builder

You can create a custom form builder that uses Simple Form.

Create a helper method that calls simple_form_for with a custom builder:

def custom_form_for(object, *args, &block)
  options = args.extract_options!
  simple_form_for(object, *(args << options.merge(builder: CustomFormBuilder)), &block)
end

Create a form builder class that inherits from SimpleForm::FormBuilder.

class CustomFormBuilder < SimpleForm::FormBuilder
  def input(attribute_name, options = {}, &block)
    super(attribute_name, options.merge(label: false), &block)
  end
end

I18n

Simple Form uses all power of I18n API to lookup labels, hints, prompts and placeholders. To customize your forms you can create a locale file like this:

en:
  simple_form:
    labels:
      user:
        username: 'User name'
        password: 'Password'
    hints:
      user:
        username: 'User name to sign in.'
        password: 'No special characters, please.'
    placeholders:
      user:
        username: 'Your username'
        password: '****'
    include_blanks:
      user:
        age: 'Rather not say'
    prompts:
      user:
        role: 'Select your role'

And your forms will use this information to render the components for you.

Simple Form also lets you be more specific, separating lookups through actions. Let's say you want a different label for new and edit actions, the locale file would be something like:

en:
  simple_form:
    labels:
      user:
        username: 'User name'
        password: 'Password'
        edit:
          username: 'Change user name'
          password: 'Change password'

This way Simple Form will figure out the right translation for you, based on the action being rendered. And to be a little bit DRYer with your locale file, you can specify defaults for all models under the 'defaults' key:

en:
  simple_form:
    labels:
      defaults:
        username: 'User name'
        password: 'Password'
        new:
          username: 'Choose a user name'
    hints:
      defaults:
        username: 'User name to sign in.'
        password: 'No special characters, please.'
    placeholders:
      defaults:
        username: 'Your username'
        password: '****'

Simple Form will always look for a default attribute translation under the "defaults" key if no specific is found inside the model key.

In addition, Simple Form will fallback to default human_attribute_name from Rails when no other translation is found for labels. Finally, you can also overwrite any label, hint or placeholder inside your view, just by passing the option manually. This way the I18n lookup will be skipped.

For :prompt and :include_blank the I18n lookup is optional and to enable it is necessary to pass :translate as value.

f.input :role, prompt: :translate

Simple Form also has support for translating options in collection helpers. For instance, given a User with a :role attribute, you might want to create a select box showing translated labels that would post either :admin or :editor as value. With Simple Form you could create an input like this:

f.input :role, collection: [:admin, :editor]

And Simple Form will try a lookup like this in your locale file, to find the right labels to show:

en:
  simple_form:
    options:
      user:
        role:
          admin: 'Administrator'
          editor: 'Editor'

You can also use the defaults key as you would do with labels, hints and placeholders. It is important to notice that Simple Form will only do the lookup for options if you give a collection composed of symbols only. This is to avoid constant lookups to I18n.

It's also possible to translate buttons, using Rails' built-in I18n support:

en:
  helpers:
    submit:
      user:
        create: "Add %{model}"
        update: "Save Changes"

There are other options that can be configured through I18n API, such as required text and boolean. Be sure to check our locale file or the one copied to your application after you run rails generate simple_form:install.

It should be noted that translations for labels, hints and placeholders for a namespaced model, e.g. Admin::User, should be placed under admin_user, not under admin/user. This is different from how translations for namespaced model and attribute names are defined:

en:
  activerecord:
    models:
        admin/user: User
    attributes:
        admin/user:
            name: Name

They should be placed under admin/user. Form labels, hints and placeholders for those attributes, though, should be placed under admin_user:

en:
  simple_form:
    labels:
        admin_user:
            name: Name

This difference exists because Simple Form relies on object_name provided by Rails' FormBuilder to determine the translation path for a given object instead of i18n_key from the object itself. Thus, similarly, if a form for an Admin::User object is defined by calling simple_form_for @admin_user, as: :some_user, Simple Form will look for translations under some_user instead of admin_user.

When translating simple_fields_for attributes be sure to use the same name you pass to it, e.g. simple_fields_for :posts should be placed under posts not post:

en:
  simple_form:
    labels:
      posts:
        title: 'Post title'
    hints:
      posts:
        title: 'A good title'
    placeholders:
      posts:
        title: 'Once upon a time...'

Configuration

Simple Form has several configuration options. You can read and change them in the initializer created by Simple Form, so if you haven't executed the command below yet, please do:

rails generate simple_form:install

The wrappers API

With Simple Form you can configure how your components will be rendered using the wrappers API. The syntax looks like this:

config.wrappers tag: :div, class: :input,
                error_class: :field_with_errors,
                valid_class: :field_without_errors do |b|

  # Form extensions
  b.use :html5
  b.optional :pattern
  b.use :maxlength
  b.use :placeholder
  b.use :readonly

  # Form components
  b.use :label_input
  b.use :hint,  wrap_with: { tag: :span, class: :hint }
  b.use :error, wrap_with: { tag: :span, class: :error }
end

The Form components will generate the form tags like labels, inputs, hints or errors contents. The available components are:

:label         # The <label> tag alone
:input         # The <input> tag alone
:label_input   # The <label> and the <input> tags
:hint          # The hint for the input
:error         # The error for the input

The Form extensions are used to generate some attributes or perform some lookups on the model to add extra information to your components.

You can create new Form components using the wrappers API as in the following example:

config.wrappers do |b|
  b.use :placeholder
  b.use :label_input
  b.wrapper tag: :div, class: 'separator' do |component|
    component.use :hint,  wrap_with: { tag: :span, class: :hint }
    component.use :error, wrap_with: { tag: :span, class: :error }
  end
end

this will wrap the hint and error components within a div tag using the class 'separator'.

You can customize Form components passing options to them:

config.wrappers do |b|
  b.use :label_input, class: 'label-input-class', error_class: 'is-invalid', valid_class: 'is-valid'
end

This sets the input and label classes to 'label-input-class' and will set the class 'is-invalid' if the input has errors and 'is-valid' if the input is valid.

If you want to customize the custom Form components on demand you can give it a name like this:

config.wrappers do |b|
  b.use :placeholder
  b.use :label_input
  b.wrapper :my_wrapper, tag: :div, class: 'separator', html: { id: 'my_wrapper_id' } do |component|
    component.use :hint,  wrap_with: { tag: :span, class: :hint }
    component.use :error, wrap_with: { tag: :span, class: :error }
  end
end

and now you can pass options to your input calls to customize the :my_wrapper Form component.

# Completely turns off the custom wrapper
f.input :name, my_wrapper: false

# Configure the html
f.input :name, my_wrapper_html: { id: 'special_id' }

# Configure the tag
f.input :name, my_wrapper_tag: :p

You can also define more than one wrapper and pick one to render in a specific form or input. To define another wrapper you have to give it a name, as the follow:

config.wrappers :small do |b|
  b.use :placeholder
  b.use :label_input
end

and use it in this way:

# Specifying to whole form
simple_form_for @user, wrapper: :small do |f|
  f.input :name
end

# Specifying to one input
simple_form_for @user do |f|
  f.input :name, wrapper: :small
end

Simple Form also allows you to use optional elements. For instance, let's suppose you want to use hints or placeholders, but you don't want them to be generated automatically. You can set their default values to false or use the optional method. Is preferable to use the optional syntax:

config.wrappers placeholder: false do |b|
  b.use :placeholder
  b.use :label_input
  b.wrapper tag: :div, class: 'separator' do |component|
    component.optional :hint, wrap_with: { tag: :span, class: :hint }
    component.use :error, wrap_with: { tag: :span, class: :error }
  end
end

By setting it as optional, a hint will only be generated when hint: true is explicitly used. The same for placeholder.

It is also possible to give the option :unless_blank to the wrapper if you want to render it only when the content is present.

  b.wrapper tag: :span, class: 'hint', unless_blank: true do |component|
    component.optional :hint
  end

Custom Components

When you use custom wrappers, you might also be looking for a way to add custom components to your wrapper. The default components are:

:label         # The <label> tag alone
:input         # The <input> tag alone
:label_input   # The <label> and the <input> tags
:hint          # The hint for the input
:error         # The error for the input

A custom component might be interesting for you if your views look something like this:

<%= simple_form_for @blog do |f| %>
  <div class="row">
    <div class="span1 number">
      1
    </div>
    <div class="span8">
      <%= f.input :title %>
    </div>
  </div>
  <div class="row">
    <div class="span1 number">
      2
    </div>
    <div class="span8">
      <%= f.input :body, as: :text %>
    </div>
  </div>
<% end %>

A cleaner method to create your views would be:

<%= simple_form_for @blog, wrapper: :with_numbers do |f| %>
  <%= f.input :title, number: 1 %>
  <%= f.input :body, as: :text, number: 2 %>
<% end %>

To use the number option on the input, first, tells to Simple Form the place where the components will be:

# config/initializers/simple_form.rb
Dir[Rails.root.join('lib/components/**/*.rb')].each { |f| require f }

Create a new component within the path specified above:

# lib/components/numbers_component.rb
module NumbersComponent
  # To avoid deprecation warning, you need to make the wrapper_options explicit
  # even when they won't be used.
  def number(wrapper_options = nil)
    @number ||= begin
      options[:number].to_s.html_safe if options[:number].present?
    end
  end
end

SimpleForm.include_component(NumbersComponent)

Finally, add a new wrapper to the config/initializers/simple_form.rb file:

config.wrappers :with_numbers, tag: 'div', class: 'row', error_class: 'error' do |b|
  b.use :html5
  b.use :number, wrap_with: { tag: 'div', class: 'span1 number'}
  b.wrapper tag: 'div', class: 'span8' do |ba|
    ba.use :placeholder
    ba.use :label
    ba.use :input
    ba.use :error, wrap_with: { tag: 'span', class: 'help-inline' }
    ba.use :hint,  wrap_with: { tag: 'p', class: 'help-block' }
  end
end

HTML 5 Notice

By default, Simple Form will generate input field types and attributes that are supported in HTML5, but are considered invalid HTML for older document types such as HTML4 or XHTML1.0. The HTML5 extensions include the new field types such as email, number, search, url, tel, and the new attributes such as required, autofocus, maxlength, min, max, step.

Most browsers will not care, but some of the newer ones - in particular Chrome 10+ - use the required attribute to force a value into an input and will prevent form submission without it. Depending on the design of the application this may or may not be desired. In many cases it can break existing UI's.

It is possible to disable all HTML 5 extensions in Simple Form by removing the html5 component from the wrapper used to render the inputs.

For example, change:

config.wrappers tag: :div do |b|
  b.use :html5

  b.use :label_input
end

To:

config.wrappers tag: :div do |b|
  b.use :label_input
end

If you want to have all other HTML 5 features, such as the new field types, you can disable only the browser validation:

SimpleForm.browser_validations = false # default is true

This option adds a new novalidate property to the form, instructing it to skip all HTML 5 validation. The inputs will still be generated with the required and other attributes, that might help you to use some generic javascript validation.

You can also add novalidate to a specific form by setting the option on the form itself:

<%= simple_form_for(resource, html: { novalidate: true }) do |form| %>

Please notice that none of the configurations above will disable the placeholder component, which is an HTML 5 feature. We believe most of the newest browsers are handling this attribute just fine, and if they aren't, any plugin you use would take care of applying the placeholder. In any case, you can disable it if you really want to, by removing the placeholder component from the components list in the Simple Form configuration file.

HTML 5 date / time inputs are not generated by Simple Form by default, so using date, time or datetime will all generate select boxes using normal Rails helpers. We believe browsers are not totally ready for these yet, but you can easily opt-in on a per-input basis by passing the html5 option:

<%= f.input :expires_at, as: :date, html5: true %>

Using non Active Record objects

There are few ways to build forms with objects that don't inherit from Active Record, as follows:

You can include the module ActiveModel::Model.

class User
  include ActiveModel::Model

  attr_accessor :id, :name
end

If you are using Presenters or Decorators that inherit from SimpleDelegator you can delegate it to the model.

class UserPresenter < SimpleDelegator
  # Without that, Simple Form will consider the user model as the object.
  def to_model 
    self 
  end
end

You can define all methods required by the helpers.

class User 
  extend ActiveModel::Naming

  attr_accessor :id, :name

  def to_model
    self
  end

  def to_key 
    id 
  end

  def persisted? 
    false 
  end
end

If your object doesn't implement those methods, you must make explicit it when you are building the form

class User 
  attr_accessor :id, :name

  # The only method required to use the f.submit helper.
  def persisted? 
    false
  end
end

<%= simple_form_for(@user, as: :user, method: :post, url: users_path) do |f| %>
  <%= f.input :name %> 
  <%= f.submit 'New user' %>
<% end %>

Information

Google Group

If you have any questions, comments, or concerns please use the Google Group instead of the GitHub Issues tracker:

http://groups.google.com/group/plataformatec-simpleform

RDocs

You can view the Simple Form documentation in RDoc format here:

http://rubydoc.info/github/plataformatec/simple_form/master/frames

Bug reports

If you discover any bugs, feel free to create an issue on GitHub. Please add as much information as possible to help us in fixing the potential bug. We also encourage you to help even more by forking and sending us a pull request.

https://github.com/plataformatec/simple_form/issues

If you have discovered a security related bug, please do NOT use the GitHub issue tracker. Send an e-mail to opensource@plataformatec.com.br.

Maintainers

José Valim (https://github.com/josevalim)
Carlos Antonio da Silva (https://github.com/carlosantoniodasilva)
Rafael Mendonça França (https://github.com/rafaelfranca)
Vasiliy Ermolovich (https://github.com/nashby)

License

You are not granted rights or licenses to the trademarks of the Plataformatec, including without limitation the Simple Form name or logo.

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Stripping away all wrapper divs

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Buttons

Wrapping Rails Form Helpers

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Available input types and defaults for each column type

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HTML 5 Notice

Using non Active Record objects

Information

Google Group

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Maintainers

License