Module: ActionView::Helpers::PrototypeHelper

Included in:
JavaScriptHelper
Defined in:
lib/action_view/helpers/prototype_helper.rb,
lib/action_view/helpers/deprecated_helper.rb

Overview

Provides a set of helpers for calling Prototype JavaScript functions, including functionality to call remote methods using Ajax. This means that you can call actions in your controllers without reloading the page, but still update certain parts of it using injections into the DOM. The common use case is having a form that adds a new element to a list without reloading the page.

To be able to use these helpers, you must include the Prototype JavaScript framework in your pages. See the documentation for ActionView::Helpers::JavaScriptHelper for more information on including the necessary JavaScript.

See link_to_remote for documentation of options common to all Ajax helpers.

See also ActionView::Helpers::ScriptaculousHelper for helpers which work with the Scriptaculous controls and visual effects library.

See JavaScriptGenerator for information on updating multiple elements on the page in an Ajax response.

Defined Under Namespace

Classes: JavaScriptGenerator

Constant Summary collapse

CALLBACKS = 
Set.new([ :uninitialized, :loading, :loaded,
:interactive, :complete, :failure, :success ] +
(100..599).to_a)
AJAX_OPTIONS = 
Set.new([ :before, :after, :condition, :url,
:asynchronous, :method, :insertion, :position,
:form, :with, :update, :script ]).merge(CALLBACKS)

Instance Method Summary collapse

Instance Method Details

#evaluate_remote_response ⇒ Object

Returns ‘eval(request.responseText)’ which is the JavaScript function that form_remote_tag can call in :complete to evaluate a multiple update return document using update_element_function calls.



210
211
212
 
# File 'lib/action_view/helpers/prototype_helper.rb', line 210

def evaluate_remote_response
  "eval(request.responseText)"
end

#form_remote_tag(options = {}, &block) ⇒ Object

Returns a form tag that will submit using XMLHttpRequest in the background instead of the regular reloading POST arrangement. Even though it’s using JavaScript to serialize the form elements, the form submission will work just like a regular submission as viewed by the receiving side (all elements available in params). The options for specifying the target with :url and defining callbacks is the same as link_to_remote.

A “fall-through” target for browsers that doesn’t do JavaScript can be specified with the :action/:method options on :html.

Example:

form_remote_tag :html => { :action => 
  url_for(:controller => "some", :action => "place") }

The Hash passed to the :html key is equivalent to the options (2nd) argument in the FormTagHelper.form_tag method.

By default the fall-through action is the same as the one specified in the :url (and the default method is :post).

form_remote_tag also takes a block, like form_tag:

<% form_remote_tag :url => '/posts' do -%>
  <div><%= submit_tag 'Save' %></div>
<% end -%>



172
173
174
175
176
177
178
179
180
181
 
# File 'lib/action_view/helpers/prototype_helper.rb', line 172

def form_remote_tag(options = {}, &block)
  options[:form] = true

  options[:html] ||= {}
  options[:html][:onsubmit] = 
    (options[:html][:onsubmit] ? options[:html][:onsubmit] + "; " : "") + 
    "#{remote_function(options)}; return false;"

  form_tag(options[:html].delete(:action) || url_for(options[:url]), options[:html], &block)
end

#link_to_remote(name, options = {}, html_options = {}) ⇒ Object

Returns a link to a remote action defined by options[:url] (using the url_for format) that’s called in the background using XMLHttpRequest. The result of that request can then be inserted into a DOM object whose id can be specified with options[:update]. Usually, the result would be a partial prepared by the controller with render :partial.

Examples:

link_to_remote "Delete this post", :update => "posts", 
  :url => { :action => "destroy", :id => post.id }
link_to_remote(image_tag("refresh"), :update => "emails", 
  :url => { :action => "list_emails" })

You can also specify a hash for options[:update] to allow for easy redirection of output to an other DOM element if a server-side error occurs:

Example:

link_to_remote "Delete this post",
  :url => { :action => "destroy", :id => post.id },
  :update => { :success => "posts", :failure => "error" }

Optionally, you can use the options[:position] parameter to influence how the target DOM element is updated. It must be one of :before, :top, :bottom, or :after.

The method used is by default POST. You can also specify GET or you can simulate PUT or DELETE over POST. All specified with options[:method]

Example:

link_to_remote "Destroy", :url => person_url(:id => person), :method => :delete

By default, these remote requests are processed asynchronous during which various JavaScript callbacks can be triggered (for progress indicators and the likes). All callbacks get access to the request object, which holds the underlying XMLHttpRequest.

To access the server response, use request.responseText, to find out the HTTP status, use request.status.

Example:

link_to_remote word,
  :url => { :action => "undo", :n => word_counter },
  :complete => "undoRequestCompleted(request)"

The callbacks that may be specified are (in order):

:loading

Called when the remote document is being loaded with data by the browser.

:loaded

Called when the browser has finished loading the remote document.

:interactive

Called when the user can interact with the remote document, even though it has not finished loading.

:success

Called when the XMLHttpRequest is completed, and the HTTP status code is in the 2XX range.

:failure

Called when the XMLHttpRequest is completed, and the HTTP status code is not in the 2XX range.

:complete

Called when the XMLHttpRequest is complete (fires after success/failure if they are present).

You can further refine :success and :failure by adding additional callbacks for specific status codes.

Example:

link_to_remote word,
  :url => { :action => "action" },
  404 => "alert('Not found...? Wrong URL...?')",
  :failure => "alert('HTTP Error ' + request.status + '!')"

A status code callback overrides the success/failure handlers if present.

If you for some reason or another need synchronous processing (that’ll block the browser while the request is happening), you can specify options[:type] = :synchronous.

You can customize further browser side call logic by passing in JavaScript code snippets via some optional parameters. In their order of use these are:

:confirm

Adds confirmation dialog.

:condition

Perform remote request conditionally by this expression. Use this to describe browser-side conditions when request should not be initiated.

:before

Called before request is initiated.

:after

Called immediately after request was initiated and before :loading.

:submit

Specifies the DOM element ID that’s used as the parent of the form elements. By default this is the current form, but it could just as well be the ID of a table row or any other DOM element.



132
133
134
 
# File 'lib/action_view/helpers/prototype_helper.rb', line 132

def link_to_remote(name, options = {}, html_options = {})  
  link_to_function(name, remote_function(options), html_options)
end

#observe_field(field_id, options = {}) ⇒ Object

Observes the field with the DOM ID specified by field_id and makes an Ajax call when its contents have changed.

Required options are either of:

:url

url_for-style options for the action to call when the field has changed.

:function

Instead of making a remote call to a URL, you can specify a function to be called instead.

Additional options are:

:frequency

The frequency (in seconds) at which changes to this field will be detected. Not setting this option at all or to a value equal to or less than zero will use event based observation instead of time based observation.

:update

Specifies the DOM ID of the element whose innerHTML should be updated with the XMLHttpRequest response text.

:with

A JavaScript expression specifying the parameters for the XMLHttpRequest. This defaults to ‘value’, which in the evaluated context refers to the new field value. If you specify a string without a “=”, it’ll be extended to mean the form key that the value should be assigned to. So :with => “term” gives “‘term’=value”. If a “=” is present, no extension will happen.

:on

Specifies which event handler to observe. By default, it’s set to “changed” for text fields and areas and “click” for radio buttons and checkboxes. With this, you can specify it instead to be “blur” or “focus” or any other event.

Additionally, you may specify any of the options documented in link_to_remote.



287
288
289
290
291
292
293
 
# File 'lib/action_view/helpers/prototype_helper.rb', line 287

def observe_field(field_id, options = {})
  if options[:frequency] && options[:frequency] > 0
    build_observer('Form.Element.Observer', field_id, options)
  else
    build_observer('Form.Element.EventObserver', field_id, options)
  end
end

#observe_form(form_id, options = {}) ⇒ Object

Like observe_field, but operates on an entire form identified by the DOM ID form_id. options are the same as observe_field, except the default value of the :with option evaluates to the serialized (request string) value of the form.



299
300
301
302
303
304
305
 
# File 'lib/action_view/helpers/prototype_helper.rb', line 299

def observe_form(form_id, options = {})
  if options[:frequency]
    build_observer('Form.Observer', form_id, options)
  else
    build_observer('Form.EventObserver', form_id, options)
  end
end

#periodically_call_remote(options = {}) ⇒ Object

Periodically calls the specified url (options[:url]) every options[:frequency] seconds (default is 10). Usually used to update a specified div (options[:update]) with the results of the remote call. The options for specifying the target with :url and defining callbacks is the same as link_to_remote.



141
142
143
144
145
 
# File 'lib/action_view/helpers/prototype_helper.rb', line 141

def periodically_call_remote(options = {})
   frequency = options[:frequency] || 10 # every ten seconds by default
   code = "new PeriodicalExecuter(function() {#{remote_function(options)}}, #{frequency})"
   javascript_tag(code)
end

#remote_form_for(object_name, *args, &proc) ⇒ Object Also known as: form_remote_for

Works like form_remote_tag, but uses form_for semantics.



184
185
186
187
188
189
 
# File 'lib/action_view/helpers/prototype_helper.rb', line 184

def remote_form_for(object_name, *args, &proc)
  options = args.last.is_a?(Hash) ? args.pop : {}
  concat(form_remote_tag(options), proc.binding)
  fields_for(object_name, *(args << options), &proc)
  concat('</form>', proc.binding)
end

#remote_function(options) ⇒ Object

Returns the JavaScript needed for a remote function. Takes the same arguments as link_to_remote.

Example:

<select id="options" onchange="<%= remote_function(:update => "options", 
    :url => { :action => :update_options }) %>">
  <option value="0">Hello</option>
  <option value="1">World</option>
</select>



223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
 
# File 'lib/action_view/helpers/prototype_helper.rb', line 223

def remote_function(options)
  javascript_options = options_for_ajax(options)

  update = ''
  if options[:update] && options[:update].is_a?(Hash)
    update  = []
    update << "success:'#{options[:update][:success]}'" if options[:update][:success]
    update << "failure:'#{options[:update][:failure]}'" if options[:update][:failure]
    update  = '{' + update.join(',') + '}'
  elsif options[:update]
    update << "'#{options[:update]}'"
  end

  function = update.empty? ? 
    "new Ajax.Request(" :
    "new Ajax.Updater(#{update}, "

  url_options = options[:url]
  url_options = url_options.merge(:escape => false) if url_options.is_a?(Hash)
  function << "'#{url_for(url_options)}'"
  function << ", #{javascript_options})"

  function = "#{options[:before]}; #{function}" if options[:before]
  function = "#{function}; #{options[:after]}"  if options[:after]
  function = "if (#{options[:condition]}) { #{function}; }" if options[:condition]
  function = "if (confirm('#{escape_javascript(options[:confirm])}')) { #{function}; }" if options[:confirm]

  return function
end

#submit_to_remote(name, value, options = {}) ⇒ Object

Returns a button input tag that will submit form using XMLHttpRequest in the background instead of regular reloading POST arrangement. options argument is the same as in form_remote_tag.



195
196
197
198
199
200
201
202
203
204
205
 
# File 'lib/action_view/helpers/prototype_helper.rb', line 195

def submit_to_remote(name, value, options = {})
  options[:with] ||= 'Form.serialize(this.form)'

  options[:html] ||= {}
  options[:html][:type] = 'button'
  options[:html][:onclick] = "#{remote_function(options)}; return false;"
  options[:html][:name] = name
  options[:html][:value] = value

  tag("input", options[:html], false)
end

#update_element_function(element_id, options = {}, &block) ⇒ Object 



5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
 
# File 'lib/action_view/helpers/deprecated_helper.rb', line 5

def update_element_function(element_id, options = {}, &block)
  content = escape_javascript(options[:content] || '')
  content = escape_javascript(capture(&block)) if block
  
  javascript_function = case (options[:action] || :update)
    when :update
      if options[:position]
        "new Insertion.#{options[:position].to_s.camelize}('#{element_id}','#{content}')"
      else
        "$('#{element_id}').innerHTML = '#{content}'"
      end
    
    when :empty
      "$('#{element_id}').innerHTML = ''"
    
    when :remove
      "Element.remove('#{element_id}')"
    
    else
      raise ArgumentError, "Invalid action, choose one of :update, :remove, :empty"
  end
  
  javascript_function << ";\n"
  options[:binding] ? concat(javascript_function, options[:binding]) : javascript_function
end

#update_page(&block) ⇒ Object

Yields a JavaScriptGenerator and returns the generated JavaScript code. Use this to update multiple elements on a page in an Ajax response. See JavaScriptGenerator for more information.



624
625
626
 
# File 'lib/action_view/helpers/prototype_helper.rb', line 624

def update_page(&block)
  JavaScriptGenerator.new(@template, &block).to_s
end

#update_page_tag(html_options = {}, &block) ⇒ Object

Works like update_page but wraps the generated JavaScript in a <script> tag. Use this to include generated JavaScript in an ERb template. See JavaScriptGenerator for more information.

html_options may be a hash of <script> attributes to be passed to ActionView::Helpers::JavaScriptHelper#javascript_tag.



634
635
636
 
# File 'lib/action_view/helpers/prototype_helper.rb', line 634

def update_page_tag(html_options = {}, &block)
  javascript_tag update_page(&block), html_options
end