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revised docs of form_for

This revision encourages the modern resource-oriented form_for usage. In addition corrects some markup and other details.
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1 parent 70e4bcf commit 0fc3381aa5359f31b36057d7bfba2e0eb6a3c064 @fxn fxn committed May 16, 2008
Showing with 56 additions and 28 deletions.
  1. +56 −28 actionpack/lib/action_view/helpers/form_helper.rb
@@ -73,30 +73,54 @@ module Helpers
# There are also methods for helping to build form tags in link:classes/ActionView/Helpers/FormOptionsHelper.html,
# link:classes/ActionView/Helpers/DateHelper.html, and link:classes/ActionView/Helpers/ActiveRecordHelper.html
module FormHelper
- # Creates a form and a scope around a specific model object that is used as a base for questioning about
- # values for the fields.
+ # Creates a form and a scope around a specific model object that is used as
+ # a base for questioning about values for the fields.
#
- # <% form_for :person, @person, :url => { :action => "update" } do |f| %>
- # <%= f.error_messages %>
- # First name: <%= f.text_field :first_name %>
- # Last name : <%= f.text_field :last_name %>
- # Biography : <%= f.text_area :biography %>
- # Admin? : <%= f.check_box :admin %>
+ # Rails provides succint resource-oriented form generation with +form_for+
+ # like this:
+ #
+ # <% form_for @offer do |f| %>
+ # <%= f.label :version, 'Version' %>:
+ # <%= f.text_field :version %><br />
+ # <%= f.label :author, 'Author' %>:
+ # <%= f.text_field :author %><br />
# <% end %>
#
- # Worth noting is that the form_for tag is called in a ERb evaluation block, not an ERb output block. So that's <tt><% %></tt>,
- # not <tt><%= %></tt>. Also worth noting is that form_for yields a <tt>form_builder</tt> object, in this example as <tt>f</tt>, which emulates
- # the API for the stand-alone FormHelper methods, but without the object name. So instead of <tt>text_field :person, :name</tt>,
- # you get away with <tt>f.text_field :name</tt>. Notice that you can even do <tt><%= f.error_messages %></tt> to display the
- # error messsages of the model object in question.
+ # There, +form_for+ is able to generate the rest of RESTful parameters
+ # based on introspection on the record, but to understand what it does we
+ # need to dig first into the alternative generic usage it is based upon.
+ #
+ # === Generic form_for
#
- # Even further, the form_for method allows you to more easily escape the instance variable convention. So while the stand-alone
- # approach would require <tt>text_field :person, :name, :object => person</tt>
- # to work with local variables instead of instance ones, the form_for calls remain the same. You simply declare once with
- # <tt>:person, person</tt> and all subsequent field calls save <tt>:person</tt> and <tt>:object => person</tt>.
+ # The generic way to call +form_for+ requires a few arguments:
#
- # Also note that form_for doesn't create an exclusive scope. It's still possible to use both the stand-alone FormHelper methods
- # and methods from FormTagHelper. For example:
+ # <% form_for :person, @person, :url => { :action => "update" } do |f| %>
+ # <%= f.error_messages %>
+ # First name: <%= f.text_field :first_name %><br />
+ # Last name : <%= f.text_field :last_name %><br />
+ # Biography : <%= f.text_area :biography %><br />
+ # Admin? : <%= f.check_box :admin %><br />
+ # <% end %>
+ #
+ # Worth noting is that the +form_for+ tag is called in a ERb evaluation block,
+ # not an ERb output block. So that's <tt><% %></tt>, not <tt><%= %></tt>. Also
+ # worth noting is that +form_for+ yields a form builder object, in this
+ # example as +f+, which emulates the API for the stand-alone FormHelper
+ # methods, but without the object name. So instead of <tt>text_field :person, :name</tt>,
+ # you get away with <tt>f.text_field :name</tt>. Notice that you can even do
+ # <tt><%= f.error_messages %></tt> to display the error messsages of the model
+ # object in question.
+ #
+ # Even further, the +form_for+ method allows you to more easily escape the
+ # instance variable convention. So while the stand-alone approach would require
+ # <tt>text_field :person, :name, :object => person</tt> to work with local
+ # variables instead of instance ones, the +form_for+ calls remain the same.
+ # You simply declare once with <tt>:person, person</tt> and all subsequent
+ # field calls save <tt>:person</tt> and <tt>:object => person</tt>.
+ #
+ # Also note that +form_for+ doesn't create an exclusive scope. It's still
+ # possible to use both the stand-alone FormHelper methods and methods from
+ # FormTagHelper. For example:
#
# <% form_for :person, @person, :url => { :action => "update" } do |f| %>
# First name: <%= f.text_field :first_name %>
@@ -105,22 +129,26 @@ module FormHelper
# Admin? : <%= check_box_tag "person[admin]", @person.company.admin? %>
# <% end %>
#
- # Note: This also works for the methods in FormOptionHelper and DateHelper that are designed to work with an object as base,
- # like FormOptionHelper#collection_select and DateHelper#datetime_select.
+ # This also works for the methods in FormOptionHelper and DateHelper that are
+ # designed to work with an object as base, like FormOptionHelper#collection_select
+ # and DateHelper#datetime_select.
#
- # HTML attributes for the form tag can be given as <tt>:html => {...}</tt>. For example:
+ # HTML attributes for the form tag can be given as <tt>:html => {...}</tt>.
+ # For example:
#
# <% form_for :person, @person, :html => {:id => 'person_form'} do |f| %>
# ...
# <% end %>
#
- # The above form will then have the <tt>id</tt> attribute with the value </tt>person_form</tt>, which you can then
- # style with CSS or manipulate with JavaScript.
+ # The above form will then have the +id+ attribute with the value "person_form",
+ # which you can then style with CSS or manipulate with JavaScript.
#
# === Relying on record identification
#
- # In addition to manually configuring the form_for call, you can also rely on record identification, which will use
- # the conventions and named routes of that approach. Examples:
+ # As we said above, in addition to manually configuring the +form_for+ call,
+ # you can rely on record identification, which will use the conventions and
+ # named routes of that approach. This is the preferred way to use +form_for+
+ # nowadays:
#
# <% form_for(@post) do |f| %>
# ...
@@ -140,7 +168,7 @@ module FormHelper
#
# This will expand to be the same as:
#
- # <% form_for :post, @post, :url => posts_path, :html => { :class => "new_post", :id => "new_post" } do |f| %>
+ # <% form_for :post, Post.new, :url => posts_path, :html => { :class => "new_post", :id => "new_post" } do |f| %>
# ...
# <% end %>
#
@@ -150,7 +178,7 @@ module FormHelper
# ...
# <% end %>
#
- # And for namespaced routes, like admin_post_url:
+ # And for namespaced routes, like +admin_post_url+:
#
# <% form_for([:admin, @post]) do |f| %>
# ...

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