Module ActionView::Helpers::ActiveRecordHelper
In: lib/action_view/helpers/active_record_helper.rb

The Active Record Helper makes it easier to create forms for records kept in instance variables. The most far-reaching is the form method that creates a complete form for all the basic content types of the record (not associations or aggregations, though). This is a great of making the record quickly available for editing, but likely to prove lackluster for a complicated real-world form. In that case, it’s better to use the input method and the specialized form methods in classes/ActionView/Helpers/FormHelper.html

Methods

Public Instance methods

Returns a string containing the error message attached to the method on the object, if one exists. This error message is wrapped in a DIV tag, which can be specialized to include both a prepend_text and append_text to properly introduce the error and a css_class to style it accordingly. Examples (post has an error message "can’t be empty" on the title attribute):

  <%= error_message_on "post", "title" %> =>
    <div class="formError">can't be empty</div>

  <%= error_message_on "post", "title", "Title simply ", " (or it won't work)", "inputError" %> =>
    <div class="inputError">Title simply can't be empty (or it won't work)</div>

Returns a string with a div containing all the error messages for the object located as an instance variable by the name of object_name. This div can be tailored by the following options:

  • header_tag - Used for the header of the error div (default: h2)
  • id - The id of the error div (default: errorExplanation)
  • class - The class of the error div (default: errorExplanation)

Returns an entire form with input tags and everything for a specified Active Record object. Example (post is a new record that has a title using VARCHAR and a body using TEXT):

  form("post") =>
    <form action='/post/create' method='post'>
      <p>
        <label for="post_title">Title</label><br />
        <input id="post_title" name="post[title]" size="30" type="text" value="Hello World" />
      </p>
      <p>
        <label for="post_body">Body</label><br />
        <textarea cols="40" id="post_body" name="post[body]" rows="20">
          Back to the hill and over it again!
        </textarea>
      </p>
      <input type='submit' value='Create' />
    </form>

It’s possible to specialize the form builder by using a different action name and by supplying another block renderer. Example (entry is a new record that has a message attribute using VARCHAR):

  form("entry", :action => "sign", :input_block =>
       Proc.new { |record, column| "#{column.human_name}: #{input(record, column.name)}<br />" }) =>

    <form action='/post/sign' method='post'>
      Message:
      <input id="post_title" name="post[title]" size="30" type="text" value="Hello World" /><br />
      <input type='submit' value='Sign' />
    </form>

It’s also possible to add additional content to the form by giving it a block, such as:

  form("entry", :action => "sign") do |form|
    form << content_tag("b", "Department")
    form << collection_select("department", "id", @departments, "id", "name")
  end

Returns a default input tag for the type of object returned by the method. Example (title is a VARCHAR column and holds "Hello World"):

  input("post", "title") =>
    <input id="post_title" name="post[title]" size="30" type="text" value="Hello World" />

[Validate]