Module: ActionView::Helpers::ActiveRecordHelper

Defined in:
lib/action_view/helpers/active_record_helper.rb

Overview

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 way 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

Instance Method Summary collapse

Instance Method Details

#error_message_on(object, method, prepend_text = "", append_text = "", css_class = "formError") ⇒ Object

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 extended to include a prepend_text and/or append_text (to properly explain the error), and a css_class to style it accordingly. object should either be the name of an instance variable or the actual object. As an example, let’s say you have a model post that has an error message on the title attribute:

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

<%= 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>



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# File 'lib/action_view/helpers/active_record_helper.rb', line 91

def error_message_on(object, method, prepend_text = "", append_text = "", css_class = "formError")
  if (obj = (object.respond_to?(:errors) ? object : instance_variable_get("@#{object}"))) &&
    (errors = obj.errors.on(method))
    content_tag("div", "#{prepend_text}#{errors.is_a?(Array) ? errors.first : errors}#{append_text}", :class => css_class)
  else 
    ''
  end
end

#error_messages_for(*params) ⇒ Object

Returns a string with a DIV containing all of the error messages for the objects located as instance variables by the names given. If more than one object is specified, the errors for the objects are displayed in the order that the object names are provided.

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)

  • object - The object (or array of objects) for which to display errors, if you need to escape the instance variable convention

  • object_name - The object name to use in the header, or any text that you prefer. If object_name is not set, the name of the first object will be used.

  • header_message - The message in the header of the error div. Pass nil or an empty string to avoid the header message altogether. (default: X errors prohibited this object from being saved)

  • message - The explanation message after the header message and before the error list. Pass nil or an empty string to avoid the explanation message altogether. (default: There were problems with the following fields:)

To specify the display for one object, you simply provide its name as a parameter. For example, for the User model:

error_messages_for 'user'

To specify more than one object, you simply list them; optionally, you can add an extra object_name parameter, which will be the name used in the header message.

error_messages_for 'user_common', 'user', :object_name => 'user'

If the objects cannot be located as instance variables, you can add an extra object paremeter which gives the actual object (or array of objects to use)

error_messages_for 'user', :object => @question.user

NOTE: This is a pre-packaged presentation of the errors with embedded strings and a certain HTML structure. If what you need is significantly different from the default presentation, it makes plenty of sense to access the object.errors instance yourself and set it up. View the source of this method to see how easy it is.



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# File 'lib/action_view/helpers/active_record_helper.rb', line 131

def error_messages_for(*params)
  options = params.extract_options!.symbolize_keys
  if object = options.delete(:object)
    objects = [object].flatten
  else
    objects = params.collect {|object_name| instance_variable_get("@#{object_name}") }.compact
  end
  count   = objects.inject(0) {|sum, object| sum + object.errors.count }
  unless count.zero?
    html = {}
    [:id, :class].each do |key|
      if options.include?(key)
        value = options[key]
        html[key] = value unless value.blank?
      else
        html[key] = 'errorExplanation'
      end
    end
    options[:object_name] ||= params.first
    options[:header_message] = "#{pluralize(count, 'error')} prohibited this #{options[:object_name].to_s.gsub('_', ' ')} from being saved" unless options.include?(:header_message)
    options[:message] ||= 'There were problems with the following fields:' unless options.include?(:message)
    error_messages = objects.map {|object| object.errors.full_messages.map {|msg| content_tag(:li, msg) } }

    contents = ''
    contents << content_tag(options[:header_tag] || :h2, options[:header_message]) unless options[:header_message].blank?
    contents << content_tag(:p, options[:message]) unless options[:message].blank?
    contents << content_tag(:ul, error_messages)

    content_tag(:div, contents, html)
  else
    ''
  end
end

#form(record_name, options = {}) {|contents| ... } ⇒ Object

Returns an entire form with all needed input tags for a specified Active Record object. For example, let’s say you have a table model Post with attributes named title of type VARCHAR and body of type TEXT:

form("post")

That line would yield a form like the following:

<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">
    </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. For example, let’s say you have a model Entry with an attribute message of type 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

Yields:

  • (contents) 


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# File 'lib/action_view/helpers/active_record_helper.rb', line 59

def form(record_name, options = {})
  record = instance_variable_get("@#{record_name}")

  options = options.symbolize_keys
  options[:action] ||= record.new_record? ? "create" : "update"
  action = url_for(:action => options[:action], :id => record)

  submit_value = options[:submit_value] || options[:action].gsub(/[^\w]/, '').capitalize

  contents = ''
  contents << hidden_field(record_name, :id) unless record.new_record?
  contents << all_input_tags(record, record_name, options)
  yield contents if block_given?
  contents << submit_tag(submit_value)

  content_tag('form', contents, :action => action, :method => 'post', :enctype => options[:multipart] ? 'multipart/form-data': nil)
end

#input(record_name, method, options = {}) ⇒ Object

Returns a default input tag for the type of object returned by the method. For example, let’s say you have a model that has an attribute title of type VARCHAR column, and this instance holds “Hello World”:

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



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# File 'lib/action_view/helpers/active_record_helper.rb', line 20

def input(record_name, method, options = {})
  InstanceTag.new(record_name, method, self).to_tag(options)
end