rails form helpers

<%= text_field(:person, :name) %>

<input id="person_name" name="person[name]" type="text" value="Henry"/>

You can create a similar binding without actually creating <form> tags with the fields_for helper. This is useful for editing additional model objects with the same form. For example if you had a Person model with an associated ContactDetail model you could create a form for creating both like so:

<%= form_for :person, @person, :url => { :action => "create" } do |person_form| %>
  <%= person_form.text_field :name %>
  <%= fields_for @person.contact_detail do |contact_details_form| %>
    <%= contact_details_form.text_field :phone_number %>
  <% end %>
<% end %>

## Creating a new article
# long-style:
form_for(:article, @article, :url => articles_path)
# same thing, short-style (record identification gets used):
form_for(@article)
 
## Editing an existing article
# long-style:
form_for(:article, @article, :url => article_path(@article), :html => { :method => "put" })
# short-style:
form_for(@article)

If you have created namespaced routes, form_for has a nifty shorthand for that too. If your application has an admin namespace then

form_for [:admin, @article]

<%= select_tag(:city_id, options_for_select(...)) %>

<%= options_for_select([['Lisbon', 1], ['Madrid', 2], ...], 2) %>
 
output:
 
<option value="1">Lisbon</option>
<option value="2" selected="selected">Madrid</option>
...

Select Boxes for Dealing with Models

 Consistent with other form helpers, when dealing with models you drop the _tag suffix from select_tag:

# controller:
@person = Person.new(:city_id => 2)

# view:
<%= select(:person, :city_id, [['Lisbon', 1], ['Madrid', 2], ...]) %>

# select on a form builder
<%= f.select(:city_id, ...) %>

Option Tags from a Collection of Arbitrary Objects

<%= options_from_collection_for_select(City.all, :id, :name) %>

<%= collection_select(:person, :city_id, City.all, :id, :name) %>

Uploading Files

<%= form_tag({:action => :upload}, :multipart => true) do %>
  <%= file_field_tag 'picture' %>
<% end %>
 
<%= form_for @person, :html => {:multipart => true} do |f| %>
  <%= f.file_field :picture %>
<% end %>