Class: ActionView::Helpers::FormBuilder
Relationships & Source Files | |
Inherits: | Object |
Defined in: | actionview/lib/action_view/helpers/form_helper.rb, actionview/lib/action_view/helpers/date_helper.rb, actionview/lib/action_view/helpers/form_options_helper.rb |
Overview
Action View Form Builder
A FormBuilder
object is associated with a particular model object and allows you to generate fields associated with the model object. The FormBuilder
object is yielded when using form_for
or #fields_for. For example:
<%= form_for @person do |person_form| %>
Name: <%= person_form.text_field :name %>
Admin: <%= person_form.check_box :admin %>
<% end %>
In the above block, a FormBuilder
object is yielded as the person_form
variable. This allows you to generate the #text_field and #check_box fields by specifying their eponymous methods, which modify the underlying template and associates the @person
model object with the form.
The FormBuilder
object can be thought of as serving as a proxy for the methods in the FormHelper
module. This class, however, allows you to call methods with the model object you are building the form for.
You can create your own custom FormBuilder
templates by subclassing this class. For example:
class MyFormBuilder < ActionView::Helpers::FormBuilder
def (method, tag_value, = {})
@template.content_tag(:div,
@template. (
@object_name, method, tag_value, ( )
)
)
end
end
The above code creates a new method div_radio_button
which wraps a div around the new radio button. Note that when options are passed in, you must call #objectify_options in order for the model object to get correctly passed to the method. If #objectify_options is not called, then the newly created helper will not be linked back to the model.
The div_radio_button
code from above can now be used as follows:
<%= form_for @person, :builder => MyFormBuilder do |f| %>
I am a child: <%= f.div_radio_button(:admin, "child") %>
I am an adult: <%= f.div_radio_button(:admin, "adult") %>
<% end -%>
The standard set of helper methods for form building are located in the .field_helpers class attribute.
Class Attribute Summary
Class Method Summary
Instance Attribute Summary
- #field_helpers rw
- #field_helpers? ⇒ Boolean rw
- #index readonly
- #multipart=(multipart) rw
-
#multipart?
rw
Alias for #multipart.
- #object rw
- #object_name rw
- #options rw
Instance Method Summary
-
#button(value = nil, options = {}, &block)
Add the submit button for the given form.
-
#check_box(method, options = {}, checked_value = "1", unchecked_value = "0")
Returns a checkbox tag tailored for accessing a specified attribute (identified by
method
) on an object assigned to the template (identified by #object). -
#collection_check_boxes(method, collection, value_method, text_method, options = {}, html_options = {}, &block)
Wraps FormOptionsHelper#collection_check_boxes for form builders:
-
#collection_radio_buttons(method, collection, value_method, text_method, options = {}, html_options = {}, &block)
Wraps FormOptionsHelper#collection_radio_buttons for form builders:
-
#collection_select(method, collection, value_method, text_method, options = {}, html_options = {})
Wraps FormOptionsHelper#collection_select for form builders:
-
#color_field(method, options = {})
Wraps FormHelper#color_field for form builders:
-
#date_field(method, options = {})
Wraps FormHelper#date_field for form builders:
-
#date_select(method, options = {}, html_options = {})
Wraps DateHelper#date_select for form builders:
-
#datetime_field(method, options = {})
Wraps FormHelper#datetime_field for form builders:
-
#datetime_local_field(method, options = {})
Wraps FormHelper#datetime_local_field for form builders:
-
#datetime_select(method, options = {}, html_options = {})
Wraps DateHelper#datetime_select for form builders:
-
#email_field(method, options = {})
Wraps FormHelper#email_field for form builders:
-
#field_id(method, *suffixes, namespace: , index: )
Generate an HTML #id attribute value for the given field.
-
#field_name(method, *methods, multiple: false, index: )
Generate an HTML
name
attribute value for the given name and field combination. -
#fields(scope = nil, model: nil, **options, &block)
See the docs for the FormHelper#fields helper method.
-
#fields_for(record_name, record_object = nil, fields_options = nil, &block)
Creates a scope around a specific model object like form_for, but doesn’t create the form tags themselves.
-
#file_field(method, options = {})
Returns a file upload input tag tailored for accessing a specified attribute (identified by
method
) on an object assigned to the template (identified by #object). -
#grouped_collection_select(method, collection, group_method, group_label_method, option_key_method, option_value_method, options = {}, html_options = {})
Wraps FormOptionsHelper#grouped_collection_select for form builders:
-
#hidden_field(method, options = {})
Returns a hidden input tag tailored for accessing a specified attribute (identified by
method
) on an object assigned to the template (identified by #object). -
#id
Generate an HTML
id
attribute value. -
#label(method, text = nil, options = {}, &block)
Returns a label tag tailored for labelling an input field for a specified attribute (identified by
method
) on an object assigned to the template (identified by #object). -
#month_field(method, options = {})
Wraps FormHelper#month_field for form builders:
- #multipart (also: #multipart?) rw
-
#number_field(method, options = {})
Wraps FormHelper#number_field for form builders:
-
#password_field(method, options = {})
Wraps FormHelper#password_field for form builders:
-
#phone_field(method, options = {})
Wraps FormHelper#phone_field for form builders:
-
#radio_button(method, tag_value, options = {})
Returns a radio button tag for accessing a specified attribute (identified by
method
) on an object assigned to the template (identified by #object). -
#range_field(method, options = {})
Wraps FormHelper#range_field for form builders:
-
#search_field(method, options = {})
Wraps FormHelper#search_field for form builders:
-
#select(method, choices = nil, options = {}, html_options = {}, &block)
Wraps FormOptionsHelper#select for form builders:
-
#submit(value = nil, options = {})
Add the submit button for the given form.
-
#telephone_field(method, options = {})
Wraps FormHelper#telephone_field for form builders:
-
#text_area(method, options = {})
Wraps FormHelper#text_area for form builders:
-
#text_field(method, options = {})
Wraps FormHelper#text_field for form builders:
-
#time_field(method, options = {})
Wraps FormHelper#time_field for form builders:
-
#time_select(method, options = {}, html_options = {})
Wraps DateHelper#time_select for form builders:
-
#time_zone_select(method, priority_zones = nil, options = {}, html_options = {})
Wraps FormOptionsHelper#time_zone_select for form builders:
- #to_model
- #to_partial_path
-
#url_field(method, options = {})
Wraps FormHelper#url_field for form builders:
-
#week_field(method, options = {})
Wraps FormHelper#week_field for form builders:
-
#weekday_select(method, options = {}, html_options = {})
Wraps FormOptionsHelper#weekday_select for form builders:
Constructor Details
.new(object_name, object, template, options) ⇒ FormBuilder
# File 'actionview/lib/action_view/helpers/form_helper.rb', line 1715
def initialize(object_name, object, template, ) @nested_child_index = {} @object_name, @object, @template, @options = object_name, object, template, @default_options = @options ? @options.slice(:index, :namespace, :skip_default_ids, :allow_method_names_outside_object) : {} @default_html_options = @default_options.except(:skip_default_ids, :allow_method_names_outside_object) (@options) if @object_name&.end_with?("[]") if (object ||= @template.instance_variable_get("@#{@object_name[0..-3]}")) && object.respond_to?(:to_param) @auto_index = object.to_param else raise ArgumentError, "object[] naming but object param and @object var don't exist or don't respond to to_param: #{object.inspect}" end end @multipart = nil @index = [:index] || [:child_index] end
Class Attribute Details
.field_helpers (rw)
[ GitHub ]# File 'actionview/lib/action_view/helpers/form_helper.rb', line 1680
class_attribute :field_helpers, default: [ :fields_for, :fields, :label, :text_field, :password_field, :hidden_field, :file_field, :text_area, :check_box, :, :color_field, :search_field, :telephone_field, :phone_field, :date_field, :time_field, :datetime_field, :datetime_local_field, :month_field, :week_field, :url_field, :email_field, :number_field, :range_field ]
.field_helpers? ⇒ Boolean
(rw)
[ GitHub ]
# File 'actionview/lib/action_view/helpers/form_helper.rb', line 1680
class_attribute :field_helpers, default: [ :fields_for, :fields, :label, :text_field, :password_field, :hidden_field, :file_field, :text_area, :check_box, :, :color_field, :search_field, :telephone_field, :phone_field, :date_field, :time_field, :datetime_field, :datetime_local_field, :month_field, :week_field, :url_field, :email_field, :number_field, :range_field ]
Class Method Details
._to_partial_path
[ GitHub ]# File 'actionview/lib/action_view/helpers/form_helper.rb', line 1703
def self._to_partial_path @_to_partial_path ||= name.demodulize.underscore.sub!(/_builder$/, "") end
Instance Attribute Details
#field_helpers (rw)
[ GitHub ]# File 'actionview/lib/action_view/helpers/form_helper.rb', line 1680
class_attribute :field_helpers, default: [ :fields_for, :fields, :label, :text_field, :password_field, :hidden_field, :file_field, :text_area, :check_box, :, :color_field, :search_field, :telephone_field, :phone_field, :date_field, :time_field, :datetime_field, :datetime_local_field, :month_field, :week_field, :url_field, :email_field, :number_field, :range_field ]
#field_helpers? ⇒ Boolean
(rw)
[ GitHub ]
# File 'actionview/lib/action_view/helpers/form_helper.rb', line 1680
class_attribute :field_helpers, default: [ :fields_for, :fields, :label, :text_field, :password_field, :hidden_field, :file_field, :text_area, :check_box, :, :color_field, :search_field, :telephone_field, :phone_field, :date_field, :time_field, :datetime_field, :datetime_local_field, :month_field, :week_field, :url_field, :email_field, :number_field, :range_field ]
#index (readonly)
[ GitHub ]# File 'actionview/lib/action_view/helpers/form_helper.rb', line 1692
attr_reader :multipart, :index
#multipart=(multipart) (rw)
[ GitHub ]#multipart? (rw)
Alias for #multipart.
# File 'actionview/lib/action_view/helpers/form_helper.rb', line 1693
alias :multipart? :multipart
#object (rw)
[ GitHub ]# File 'actionview/lib/action_view/helpers/form_helper.rb', line 1690
attr_accessor :object_name, :object, :
#object_name (rw)
[ GitHub ]# File 'actionview/lib/action_view/helpers/form_helper.rb', line 1690
attr_accessor :object_name, :object, :
#options (rw)
[ GitHub ]# File 'actionview/lib/action_view/helpers/form_helper.rb', line 1690
attr_accessor :object_name, :object, :
Instance Method Details
#button(value = nil, options = {}, &block)
Add the submit button for the given form. When no value is given, it checks if the object is a new resource or not to create the proper label:
<%= form_for @post do |f| %>
<%= f.button %>
<% end %>
In the example above, if @post
is a new record, it will use “Create Post” as button label; otherwise, it uses “Update Post”.
Those labels can be customized using ::I18n
under the helpers.submit
key (the same as submit helper) and using %{model}
for translation interpolation:
en:
helpers:
submit:
create: "Create a %{model}"
update: "Confirm changes to %{model}"
It also searches for a key specific to the given object:
en:
helpers:
submit:
post:
create: "Add %{model}"
Examples
"Create post")
# => <button name='button' type='submit'>Create post</button>
(:draft, value: true)
# => <button id="post_draft" name="post[draft]" value="true" type="submit">Create post</button>
do
content_tag(:strong, 'Ask me!')
end
# => <button name='button' type='submit'>
# <strong>Ask me!</strong>
# </button>
do |text|
content_tag(:strong, text)
end
# => <button name='button' type='submit'>
# <strong>Create post</strong>
# </button>
(:draft, value: true) do
content_tag(:strong, "Save as draft")
end
# => <button id="post_draft" name="post[draft]" value="true" type="submit">
# <strong>Save as draft</strong>
# </button>
(
# File 'actionview/lib/action_view/helpers/form_helper.rb', line 2644
def (value = nil, = {}, &block) case value when Hash value, = nil, value when Symbol value, = nil, { name: field_name(value), id: field_id(value) }.merge!( .to_h) end value ||= submit_default_value if block_given? value = @template.capture { yield(value) } end formmethod = [:formmethod] if formmethod.present? && !/post|get/i.match?(formmethod) && ! .key?(:name) && ! .key?(:value) .merge! formmethod: :post, name: "_method", value: formmethod end @template. (value, ) end
#check_box(method, options = {}, checked_value = "1", unchecked_value = "0")
Returns a checkbox tag tailored for accessing a specified attribute (identified by method
) on an object assigned to the template (identified by #object). This object must be an instance object (@object) and not a local object. It’s intended that method
returns an integer and if that integer is above zero, then the checkbox is checked. Additional options on the input tag can be passed as a hash with #options. The checked_value
defaults to 1 while the default unchecked_value
is set to 0 which is convenient for boolean values.
Options
-
Any standard HTML attributes for the tag can be passed in, for example
:class
. -
:checked
-true
orfalse
forces the state of the checkbox to be checked or not. -
:include_hidden
- If set to false, the auxiliary hidden field described below will not be generated.
Gotcha
The HTML specification says unchecked check boxes are not successful, and thus web browsers do not send them. Unfortunately this introduces a gotcha: if an Invoice
model has a paid
flag, and in the form that edits a paid invoice the user unchecks its check box, no paid
parameter is sent. So, any mass-assignment idiom like
@invoice.update(params[:invoice])
wouldn’t update the flag.
To prevent this the helper generates an auxiliary hidden field before every check box. The hidden field has the same name and its attributes mimic an unchecked check box.
This way, the client either sends only the hidden field (representing the check box is unchecked), or both fields. Since the HTML specification says key/value pairs have to be sent in the same order they appear in the form, and parameters extraction gets the last occurrence of any repeated key in the query string, that works for ordinary forms.
Unfortunately that workaround does not work when the check box goes within an array-like parameter, as in
<%= fields_for "project[invoice_attributes][]", invoice, index: nil do |form| %>
<%= form.check_box :paid %>
...
<% end %>
because parameter name repetition is precisely what Rails seeks to distinguish the elements of the array. For each item with a checked check box you get an extra ghost item with only that attribute, assigned to “0”.
In that case it is preferable to either use check_box_tag
or to use hashes instead of arrays.
Examples
# Let's say that @post.validated? is 1:
check_box("validated")
# => <input name="post[validated]" type="hidden" value="0" />
# <input checked="checked" type="checkbox" id="post_validated" name="post[validated]" value="1" />
# Let's say that @puppy.gooddog is "no":
check_box("gooddog", {}, "yes", "no")
# => <input name="puppy[gooddog]" type="hidden" value="no" />
# <input type="checkbox" id="puppy_gooddog" name="puppy[gooddog]" value="yes" />
# Let's say that @eula.accepted is "no":
check_box("accepted", { class: 'eula_check' }, "yes", "no")
# => <input name="eula[accepted]" type="hidden" value="no" />
# <input type="checkbox" class="eula_check" id="eula_accepted" name="eula[accepted]" value="yes" />
# File 'actionview/lib/action_view/helpers/form_helper.rb', line 2468
def check_box(method, = {}, checked_value = "1", unchecked_value = "0") @template.check_box(@object_name, method, ( ), checked_value, unchecked_value) end
#collection_check_boxes(method, collection, value_method, text_method, options = {}, html_options = {}, &block)
Wraps FormOptionsHelper#collection_check_boxes for form builders:
<%= form_for @post do |f| %>
<%= f.collection_check_boxes :author_ids, Author.all, :id, :name_with_initial %>
<%= f.submit %>
<% end %>
Please refer to the documentation of the base helper for details.
# File 'actionview/lib/action_view/helpers/form_options_helper.rb', line 908
def collection_check_boxes(method, collection, value_method, text_method, = {}, = {}, &block) @template.collection_check_boxes(@object_name, method, collection, value_method, text_method, ( ), @default_html_options.merge( ), &block) end
#collection_radio_buttons(method, collection, value_method, text_method, options = {}, html_options = {}, &block)
Wraps FormOptionsHelper#collection_radio_buttons for form builders:
<%= form_for @post do |f| %>
<%= f.collection_radio_buttons :author_id, Author.all, :id, :name_with_initial %>
<%= f.submit %>
<% end %>
Please refer to the documentation of the base helper for details.
# File 'actionview/lib/action_view/helpers/form_options_helper.rb', line 920
def (method, collection, value_method, text_method, = {}, = {}, &block) @template. (@object_name, method, collection, value_method, text_method, ( ), @default_html_options.merge( ), &block) end
#collection_select(method, collection, value_method, text_method, options = {}, html_options = {})
Wraps FormOptionsHelper#collection_select for form builders:
<%= form_for @post do |f| %>
<%= f.collection_select :person_id, Author.all, :id, :name_with_initial, prompt: true %>
<%= f.submit %>
<% end %>
Please refer to the documentation of the base helper for details.
# File 'actionview/lib/action_view/helpers/form_options_helper.rb', line 860
def collection_select(method, collection, value_method, text_method, = {}, = {}) @template.collection_select(@object_name, method, collection, value_method, text_method, ( ), @default_html_options.merge( )) end
#color_field(method, options = {})
Wraps FormHelper#color_field for form builders:
<%= form_with model: @user do |f| %>
<%= f.color_field :favorite_color %>
<% end %>
Please refer to the documentation of the base helper for details.
# File 'actionview/lib/action_view/helpers/form_helper.rb', line 1838
rdoc_method :method: color_field
#date_field(method, options = {})
Wraps FormHelper#date_field for form builders:
<%= form_with model: @user do |f| %>
<%= f.date_field :born_on %>
<% end %>
Please refer to the documentation of the base helper for details.
# File 'actionview/lib/action_view/helpers/form_helper.rb', line 1890
rdoc_method :method: date_field
#date_select(method, options = {}, html_options = {})
Wraps DateHelper#date_select for form builders:
<%= form_for @person do |f| %>
<%= f.date_select :birth_date %>
<%= f.submit %>
<% end %>
Please refer to the documentation of the base helper for details.
# File 'actionview/lib/action_view/helpers/date_helper.rb', line 1237
def date_select(method, = {}, = {}) @template.date_select(@object_name, method, ( ), ) end
#datetime_field(method, options = {})
Wraps FormHelper#datetime_field for form builders:
<%= form_with model: @user do |f| %>
<%= f.datetime_field :graduation_day %>
<% end %>
Please refer to the documentation of the base helper for details.
# File 'actionview/lib/action_view/helpers/form_helper.rb', line 1916
rdoc_method :method: datetime_field
#datetime_local_field(method, options = {})
Wraps FormHelper#datetime_local_field for form builders:
<%= form_with model: @user do |f| %>
<%= f.datetime_local_field :graduation_day %>
<% end %>
Please refer to the documentation of the base helper for details.
# File 'actionview/lib/action_view/helpers/form_helper.rb', line 1929
rdoc_method :method: datetime_local_field
#datetime_select(method, options = {}, html_options = {})
Wraps DateHelper#datetime_select for form builders:
<%= form_for @person do |f| %>
<%= f.datetime_select :last_request_at %>
<%= f.submit %>
<% end %>
Please refer to the documentation of the base helper for details.
# File 'actionview/lib/action_view/helpers/date_helper.rb', line 1261
def datetime_select(method, = {}, = {}) @template.datetime_select(@object_name, method, ( ), ) end
#email_field(method, options = {})
Wraps FormHelper#email_field for form builders:
<%= form_with model: @user do |f| %>
<%= f.email_field :address %>
<% end %>
Please refer to the documentation of the base helper for details.
# File 'actionview/lib/action_view/helpers/form_helper.rb', line 1981
rdoc_method :method: email_field
#field_id(method, *suffixes, namespace: , index: )
Generate an HTML #id attribute value for the given field
Return the value generated by the FormBuilder
for the given attribute name.
<%= form_for @post 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 #text_field declares an aria-describedby
attribute referencing the <span>
element, sharing a common #id root (post_title
, in this case).
#field_name(method, *methods, multiple: false, index: )
Generate an HTML name
attribute value for the given name and field combination
Return the value generated by the FormBuilder
for the given attribute name.
<%= form_for @post do |f| %>
<%= f.text_field :title, name: f.field_name(:title, :subtitle) %>
<%# => <input type="text" name="post[title][subtitle]"> %>
<% end %>
<%= form_for @post do |f| %>
<%= f.text_field :tag, name: f.field_name(:tag, multiple: true) %>
<%# => <input type="text" name="post[tag][]"> %>
<% end %>
# File 'actionview/lib/action_view/helpers/form_helper.rb', line 1792
def field_name(method, *methods, multiple: false, index: @options[:index]) object_name = @options.fetch(:as) { @object_name } @template.field_name(object_name, method, *methods, index: index, multiple: multiple) end
#fields(scope = nil, model: nil, **options, &block)
See the docs for the FormHelper#fields helper method.
# File 'actionview/lib/action_view/helpers/form_helper.rb', line 2322
def fields(scope = nil, model: nil, **, &block) [:allow_method_names_outside_object] = true [:skip_default_ids] = !FormHelper.form_with_generates_ids ( ) fields_for(scope || model, model, , &block) end
#fields_for(record_name, record_object = nil, fields_options = nil, &block)
Creates a scope around a specific model object like form_for, but doesn’t create the form tags themselves. This makes fields_for suitable for specifying additional model objects in the same form.
Although the usage and purpose of fields_for
is similar to form_for
‘s, its method signature is slightly different. Like form_for
, it yields a FormBuilder
object associated with a particular model object to a block, and within the block allows methods to be called on the builder to generate fields associated with the model object. Fields may reflect a model object in two ways - how they are named (hence how submitted values appear within the params
hash in the controller) and what default values are shown when the form the fields appear in is first displayed. In order for both of these features to be specified independently, both an object name (represented by either a symbol or string) and the object itself can be passed to the method separately -
<%= form_for @person do |person_form| %>
First name: <%= person_form.text_field :first_name %>
Last name : <%= person_form.text_field :last_name %>
<%= fields_for :permission, @person.permission do |permission_fields| %>
Admin? : <%= permission_fields.check_box :admin %>
<% end %>
<%= person_form.submit %>
<% end %>
In this case, the checkbox field will be represented by an HTML input
tag with the name
attribute permission[admin]
, and the submitted value will appear in the controller as params[:permission][:admin]
. If @person.permission
is an existing record with an attribute admin
, the initial state of the checkbox when first displayed will reflect the value of @person.permission.admin
.
Often this can be simplified by passing just the name of the model object to fields_for
-
<%= fields_for :permission do |permission_fields| %>
Admin?: <%= permission_fields.check_box :admin %>
<% end %>
…in which case, if :permission
also happens to be the name of an instance variable @permission
, the initial state of the input field will reflect the value of that variable’s attribute @permission.admin
.
Alternatively, you can pass just the model object itself (if the first argument isn’t a string or symbol fields_for
will realize that the name has been omitted) -
<%= fields_for @person.permission do |permission_fields| %>
Admin?: <%= permission_fields.check_box :admin %>
<% end %>
and fields_for
will derive the required name of the field from the class of the model object, e.g. if @person.permission
, is of class Permission
, the field will still be named permission[admin]
.
Note: This also works for the methods in FormOptionsHelper
and DateHelper
that are designed to work with an object as base, like FormOptionsHelper#collection_select and DateHelper#datetime_select.
fields_for
tries to be smart about parameters, but it can be confused if both name and value parameters are provided and the provided value has the shape of an option ::Hash
. To remove the ambiguity, explicitly pass an option ::Hash
, even if empty.
<%= form_for @person do |person_form| %>
...
<%= fields_for :permission, @person.permission, {} do |permission_fields| %>
Admin?: <%= check_box_tag permission_fields.field_name(:admin), @person.permission[:admin] %>
<% end %>
...
<% end %>
Nested Attributes Examples
When the object belonging to the current scope has a nested attribute writer for a certain attribute, fields_for will yield a new scope for that attribute. This allows you to create forms that set or change the attributes of a parent object and its associations in one go.
Nested attribute writers are normal setter methods named after an association. The most common way of defining these writers is either with accepts_nested_attributes_for
in a model definition or by defining a method with the proper name. For example: the attribute writer for the association :address
is called address_attributes=
.
Whether a one-to-one or one-to-many style form builder will be yielded depends on whether the normal reader method returns a single object or an array of objects.
One-to-one
Consider a Person class which returns a single Address from the address
reader method and responds to the address_attributes=
writer method:
class Person
def address
@address
end
def address_attributes=(attributes)
# Process the attributes hash
end
end
This model can now be used with a nested fields_for, like so:
<%= form_for @person do |person_form| %>
...
<%= person_form.fields_for :address do |address_fields| %>
Street : <%= address_fields.text_field :street %>
Zip code: <%= address_fields.text_field :zip_code %>
<% end %>
...
<% end %>
When address is already an association on a Person you can use accepts_nested_attributes_for
to define the writer method for you:
class Person < ActiveRecord::Base
has_one :address
accepts_nested_attributes_for :address
end
If you want to destroy the associated model through the form, you have to enable it first using the :allow_destroy
option for accepts_nested_attributes_for
:
class Person < ActiveRecord::Base
has_one :address
accepts_nested_attributes_for :address, allow_destroy: true
end
Now, when you use a form element with the _destroy
parameter, with a value that evaluates to true
, you will destroy the associated model (e.g. 1, ‘1’, true, or ‘true’):
<%= form_for @person do |person_form| %>
...
<%= person_form.fields_for :address do |address_fields| %>
...
Delete: <%= address_fields.check_box :_destroy %>
<% end %>
...
<% end %>
One-to-many
Consider a Person class which returns an array of Project instances from the projects
reader method and responds to the projects_attributes=
writer method:
class Person
def projects
[@project1, @project2]
end
def projects_attributes=(attributes)
# Process the attributes hash
end
end
Note that the projects_attributes=
writer method is in fact required for fields_for to correctly identify :projects
as a collection, and the correct indices to be set in the form markup.
When projects is already an association on Person you can use accepts_nested_attributes_for
to define the writer method for you:
class Person < ActiveRecord::Base
has_many :projects
accepts_nested_attributes_for :projects
end
This model can now be used with a nested fields_for. The block given to the nested fields_for call will be repeated for each instance in the collection:
<%= form_for @person do |person_form| %>
...
<%= person_form.fields_for :projects do |project_fields| %>
<% if project_fields.object.active? %>
Name: <%= project_fields.text_field :name %>
<% end %>
<% end %>
...
<% end %>
It’s also possible to specify the instance to be used:
<%= form_for @person do |person_form| %>
...
<% @person.projects.each do |project| %>
<% if project.active? %>
<%= person_form.fields_for :projects, project do |project_fields| %>
Name: <%= project_fields.text_field :name %>
<% end %>
<% end %>
<% end %>
...
<% end %>
Or a collection to be used:
<%= form_for @person do |person_form| %>
...
<%= person_form.fields_for :projects, @active_projects do |project_fields| %>
Name: <%= project_fields.text_field :name %>
<% end %>
...
<% end %>
If you want to destroy any of the associated models through the form, you have to enable it first using the :allow_destroy
option for accepts_nested_attributes_for
:
class Person < ActiveRecord::Base
has_many :projects
accepts_nested_attributes_for :projects, allow_destroy: true
end
This will allow you to specify which models to destroy in the attributes hash by adding a form element for the _destroy
parameter with a value that evaluates to true
(e.g. 1, ‘1’, true, or ‘true’):
<%= form_for @person do |person_form| %>
...
<%= person_form.fields_for :projects do |project_fields| %>
Delete: <%= project_fields.check_box :_destroy %>
<% end %>
...
<% end %>
When a collection is used you might want to know the index of each object in the array. For this purpose, the #index method is available in the FormBuilder
object.
<%= form_for @person do |person_form| %>
...
<%= person_form.fields_for :projects do |project_fields| %>
Project #<%= project_fields.index %>
...
<% end %>
...
<% end %>
Note that fields_for will automatically generate a hidden field to store the ID of the record. There are circumstances where this hidden field is not needed and you can pass include_id: false
to prevent fields_for from rendering it automatically.
# File 'actionview/lib/action_view/helpers/form_helper.rb', line 2284
def fields_for(record_name, record_object = nil, = nil, &block) , record_object = record_object, nil if .nil? && record_object.is_a?(Hash) && record_object. ||= {} [:builder] ||= [:builder] [:namespace] = [:namespace] [:parent_builder] = self case record_name when String, Symbol if nested_attributes_association?(record_name) return fields_for_with_nested_attributes(record_name, record_object, , block) end else record_object = @template._object_for_form_builder(record_name) record_name = model_name_from_record_or_class(record_object).param_key end object_name = @object_name index = if .has_key?(:index) [:index] elsif defined?(@auto_index) object_name = object_name.to_s.delete_suffix("[]") @auto_index end record_name = if index "#{object_name}[#{index}][#{record_name}]" elsif record_name.end_with?("[]") "#{object_name}[#{record_name[0..-3]}][#{record_object.id}]" else "#{object_name}[#{record_name}]" end [:child_index] = index @template.fields_for(record_name, record_object, , &block) end
#file_field(method, options = {})
Returns a file upload input tag tailored for accessing a specified attribute (identified by method
) on an object assigned to the template (identified by #object). Additional options on the input tag can be passed as a hash with #options. These options will be tagged onto the HTML as an HTML element attribute as in the example shown.
Using this method inside a form_with
block will set the enclosing form’s encoding to multipart/form-data
.
Options
-
Creates standard HTML attributes for the tag.
-
:disabled
- If set to true, the user will not be able to use this input. -
:multiple
- If set to true, *in most updated browsers* the user will be allowed to select multiple files. -
:include_hidden
- Whenmultiple: true
andinclude_hidden: true
, the field will be prefixed with an<input type="hidden">
field with an empty value to support submitting an empty collection of files. Sinceinclude_hidden
will default toconfig.active_storage.multiple_file_field_include_hidden
if you don’t specifyinclude_hidden
, you will need to passinclude_hidden: false
to prevent submitting an empty collection of files when passingmultiple: true
. -
:accept
- If set to one or multiple mime-types, the user will be suggested a filter when choosing a file. You still need to set up model validations.
Examples
# Let's say that @user has avatar:
file_field(:avatar)
# => <input type="file" id="user_avatar" name="user[avatar]" />
# Let's say that @post has image:
file_field(:image, :multiple => true)
# => <input type="file" id="post_image" name="post[image][]" multiple="multiple" />
# Let's say that @post has attached:
file_field(:attached, accept: 'text/html')
# => <input accept="text/html" type="file" id="post_attached" name="post[attached]" />
# Let's say that @post has image:
file_field(:image, accept: 'image/png,image/gif,image/jpeg')
# => <input type="file" id="post_image" name="post[image]" accept="image/png,image/gif,image/jpeg" />
# Let's say that @attachment has file:
file_field(:file, class: 'file_input')
# => <input type="file" id="attachment_file" name="attachment[file]" class="file_input" />
# File 'actionview/lib/action_view/helpers/form_helper.rb', line 2551
def file_field(method, = {}) self.multipart = true @template.file_field(@object_name, method, ( )) end
#grouped_collection_select(method, collection, group_method, group_label_method, option_key_method, option_value_method, options = {}, html_options = {})
Wraps FormOptionsHelper#grouped_collection_select for form builders:
<%= form_for @city do |f| %>
<%= f.grouped_collection_select :country_id, @continents, :countries, :name, :id, :name %>
<%= f.submit %>
<% end %>
Please refer to the documentation of the base helper for details.
# File 'actionview/lib/action_view/helpers/form_options_helper.rb', line 872
def grouped_collection_select(method, collection, group_method, group_label_method, option_key_method, option_value_method, = {}, = {}) @template.grouped_collection_select(@object_name, method, collection, group_method, group_label_method, option_key_method, option_value_method, ( ), @default_html_options.merge( )) end
#id
Generate an HTML id
attribute value.
return the <form>
element’s id
attribute.
<%= form_for @post do |f| %>
<%# ... %>
<% content_for :sticky_footer do %>
<%= form.button(form: f.id) %>
<% end %>
<% end %>
In the example above, the :sticky_footer
content area will exist outside of the <form>
element. By declaring the form
HTML attribute, we hint to the browser that the generated <button>
element should be treated as the <form>
element’s submit button, regardless of where it exists in the DOM.
# File 'actionview/lib/action_view/helpers/form_helper.rb', line 1752
def id .dig(:html, :id) || [:id] end
#label(method, text = nil, options = {}, &block)
Returns a label tag tailored for labelling an input field for a specified attribute (identified by method
) on an object assigned to the template (identified by #object). The text of label will default to the attribute name unless a translation is found in the current ::I18n
locale (through helpers.label.<modelname>.<attribute>
) or you specify it explicitly. Additional options on the label tag can be passed as a hash with #options. These options will be tagged onto the HTML as an HTML element attribute as in the example shown, except for the :value
option, which is designed to target labels for radio_button tags (where the value is used in the ID of the input tag).
Examples
label(:title)
# => <label for="post_title">Title</label>
You can localize your labels based on model and attribute names. For example you can define the following in your locale (e.g. en.yml)
helpers:
label:
post:
body: "Write your entire text here"
Which then will result in
label(:body)
# => <label for="post_body">Write your entire text here</label>
Localization can also be based purely on the translation of the attribute-name (if you are using ::ActiveRecord
):
activerecord:
attributes:
post:
cost: "Total cost"
label(:cost)
# => <label for="post_cost">Total cost</label>
label(:title, "A short title")
# => <label for="post_title">A short title</label>
label(:title, "A short title", class: "title_label")
# => <label for="post_title" class="title_label">A short title</label>
label(:privacy, "Public Post", value: "public")
# => <label for="post_privacy_public">Public Post</label>
label(:cost) do |translation|
content_tag(:span, translation, class: "cost_label")
end
# => <label for="post_cost"><span class="cost_label">Total cost</span></label>
label(:cost) do |builder|
content_tag(:span, builder.translation, class: "cost_label")
end
# => <label for="post_cost"><span class="cost_label">Total cost</span></label>
label(:cost) do |builder|
content_tag(:span, builder.translation, class: [
"cost_label",
("error_label" if builder.object.errors.include?(:cost))
])
end
# => <label for="post_cost"><span class="cost_label error_label">Total cost</span></label>
label(:terms) do
raw('Accept <a href="/terms">Terms</a>.')
end
# => <label for="post_terms">Accept <a href="/terms">Terms</a>.</label>
# File 'actionview/lib/action_view/helpers/form_helper.rb', line 2399
def label(method, text = nil, = {}, &block) @template.label(@object_name, method, text, ( ), &block) end
#month_field(method, options = {})
Wraps FormHelper#month_field for form builders:
<%= form_with model: @user do |f| %>
<%= f.month_field :birthday_month %>
<% end %>
Please refer to the documentation of the base helper for details.
# File 'actionview/lib/action_view/helpers/form_helper.rb', line 1942
rdoc_method :method: month_field
#multipart (rw) Also known as: #multipart?
[ GitHub ]# File 'actionview/lib/action_view/helpers/form_helper.rb', line 1692
attr_reader :multipart, :index
#number_field(method, options = {})
Wraps FormHelper#number_field for form builders:
<%= form_with model: @user do |f| %>
<%= f.number_field :age %>
<% end %>
Please refer to the documentation of the base helper for details.
# File 'actionview/lib/action_view/helpers/form_helper.rb', line 1994
rdoc_method :method: number_field
#password_field(method, options = {})
Wraps FormHelper#password_field for form builders:
<%= form_with model: @user do |f| %>
<%= f.password_field :password %>
<% end %>
Please refer to the documentation of the base helper for details.
# File 'actionview/lib/action_view/helpers/form_helper.rb', line 1812
rdoc_method :method: password_field
#phone_field(method, options = {})
Wraps FormHelper#phone_field for form builders:
<%= form_with model: @user do |f| %>
<%= f.phone_field :phone %>
<% end %>
Please refer to the documentation of the base helper for details.
# File 'actionview/lib/action_view/helpers/form_helper.rb', line 1877
rdoc_method :method: phone_field
#radio_button(method, tag_value, options = {})
Returns a radio button tag for accessing a specified attribute (identified by method
) on an object assigned to the template (identified by #object). If the current value of method
is tag_value
the radio button will be checked.
To force the radio button to be checked pass checked: true
in the #options hash. You may pass HTML options there as well.
# Let's say that @post.category returns "rails":
("category", "rails")
("category", "java")
# => <input type="radio" id="post_category_rails" name="post[category]" value="rails" checked="checked" />
# <input type="radio" id="post_category_java" name="post[category]" value="java" />
# Let's say that @user.receive_newsletter returns "no":
("receive_newsletter", "yes")
("receive_newsletter", "no")
# => <input type="radio" id="user_receive_newsletter_yes" name="user[receive_newsletter]" value="yes" />
# <input type="radio" id="user_receive_newsletter_no" name="user[receive_newsletter]" value="no" checked="checked" />
# File 'actionview/lib/action_view/helpers/form_helper.rb', line 2490
def (method, tag_value, = {}) @template. (@object_name, method, tag_value, ( )) end
#range_field(method, options = {})
Wraps FormHelper#range_field for form builders:
<%= form_with model: @user do |f| %>
<%= f.range_field :age %>
<% end %>
Please refer to the documentation of the base helper for details.
# File 'actionview/lib/action_view/helpers/form_helper.rb', line 2020
rdoc_method :method: range_field
#search_field(method, options = {})
Wraps FormHelper#search_field for form builders:
<%= form_with model: @user do |f| %>
<%= f.search_field :name %>
<% end %>
Please refer to the documentation of the base helper for details.
# File 'actionview/lib/action_view/helpers/form_helper.rb', line 1851
rdoc_method :method: search_field
#select(method, choices = nil, options = {}, html_options = {}, &block)
Wraps FormOptionsHelper#select for form builders:
<%= form_for @post do |f| %>
<%= f.select :person_id, Person.all.collect { |p| [ p.name, p.id ] }, include_blank: true %>
<%= f.submit %>
<% end %>
Please refer to the documentation of the base helper for details.
# File 'actionview/lib/action_view/helpers/form_options_helper.rb', line 848
def select(method, choices = nil, = {}, = {}, &block) @template.select(@object_name, method, choices, ( ), @default_html_options.merge( ), &block) end
#submit(value = nil, options = {})
Add the submit button for the given form. When no value is given, it checks if the object is a new resource or not to create the proper label:
<%= form_for @post do |f| %>
<%= f.submit %>
<% end %>
In the example above, if @post
is a new record, it will use “Create Post” as submit button label; otherwise, it uses “Update Post”.
Those labels can be customized using ::I18n
under the helpers.submit
key and using %{model}
for translation interpolation:
en:
helpers:
submit:
create: "Create a %{model}"
update: "Confirm changes to %{model}"
It also searches for a key specific to the given object:
en:
helpers:
submit:
post:
create: "Add %{model}"
# File 'actionview/lib/action_view/helpers/form_helper.rb', line 2583
def submit(value = nil, = {}) value, = nil, value if value.is_a?(Hash) value ||= submit_default_value @template.submit_tag(value, ) end
#telephone_field(method, options = {})
Wraps FormHelper#telephone_field for form builders:
<%= form_with model: @user do |f| %>
<%= f.telephone_field :phone %>
<% end %>
Please refer to the documentation of the base helper for details.
# File 'actionview/lib/action_view/helpers/form_helper.rb', line 1864
rdoc_method :method: telephone_field
#text_area(method, options = {})
Wraps FormHelper#text_area for form builders:
<%= form_with model: @user do |f| %>
<%= f.text_area :detail %>
<% end %>
Please refer to the documentation of the base helper for details.
# File 'actionview/lib/action_view/helpers/form_helper.rb', line 1825
rdoc_method :method: text_area
#text_field(method, options = {})
Wraps FormHelper#text_field for form builders:
<%= form_with model: @user do |f| %>
<%= f.text_field :name %>
<% end %>
Please refer to the documentation of the base helper for details.
# File 'actionview/lib/action_view/helpers/form_helper.rb', line 1799
rdoc_method :method: text_field
#time_field(method, options = {})
Wraps FormHelper#time_field for form builders:
<%= form_with model: @user do |f| %>
<%= f.time_field :born_at %>
<% end %>
Please refer to the documentation of the base helper for details.
# File 'actionview/lib/action_view/helpers/form_helper.rb', line 1903
rdoc_method :method: time_field
#time_select(method, options = {}, html_options = {})
Wraps DateHelper#time_select for form builders:
<%= form_for @race do |f| %>
<%= f.time_select :average_lap %>
<%= f.submit %>
<% end %>
Please refer to the documentation of the base helper for details.
# File 'actionview/lib/action_view/helpers/date_helper.rb', line 1249
def time_select(method, = {}, = {}) @template.time_select(@object_name, method, ( ), ) end
#time_zone_select(method, priority_zones = nil, options = {}, html_options = {})
Wraps FormOptionsHelper#time_zone_select for form builders:
<%= form_for @user do |f| %>
<%= f.time_zone_select :time_zone, nil, include_blank: true %>
<%= f.submit %>
<% end %>
Please refer to the documentation of the base helper for details.
# File 'actionview/lib/action_view/helpers/form_options_helper.rb', line 884
def time_zone_select(method, priority_zones = nil, = {}, = {}) @template.time_zone_select(@object_name, method, priority_zones, ( ), @default_html_options.merge( )) end
#to_model
[ GitHub ]# File 'actionview/lib/action_view/helpers/form_helper.rb', line 1711
def to_model self end
#to_partial_path
[ GitHub ]# File 'actionview/lib/action_view/helpers/form_helper.rb', line 1707
def to_partial_path self.class._to_partial_path end
#url_field(method, options = {})
Wraps FormHelper#url_field for form builders:
<%= form_with model: @user do |f| %>
<%= f.url_field :homepage %>
<% end %>
Please refer to the documentation of the base helper for details.
# File 'actionview/lib/action_view/helpers/form_helper.rb', line 1968
rdoc_method :method: url_field
#week_field(method, options = {})
Wraps FormHelper#week_field for form builders:
<%= form_with model: @user do |f| %>
<%= f.week_field :birthday_week %>
<% end %>
Please refer to the documentation of the base helper for details.
# File 'actionview/lib/action_view/helpers/form_helper.rb', line 1955
rdoc_method :method: week_field
#weekday_select(method, options = {}, html_options = {})
Wraps FormOptionsHelper#weekday_select for form builders:
<%= form_for @user do |f| %>
<%= f.weekday_select :weekday, include_blank: true %>
<%= f.submit %>
<% end %>
Please refer to the documentation of the base helper for details.
# File 'actionview/lib/action_view/helpers/form_options_helper.rb', line 896
def weekday_select(method, = {}, = {}) @template.weekday_select(@object_name, method, ( ), @default_html_options.merge( )) end