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