Module | ActionView::Helpers::PrototypeHelper
In: | lib/action_view/helpers/deprecated_helper.rb lib/action_view/helpers/prototype_helper.rb

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.

### Methods

build_callbacks build_observer evaluate_remote_response form_remote_for form_remote_tag link_to_remote method_option_to_s observe_field observe_form options_for_ajax periodically_call_remote remote_form_for remote_function submit_to_remote update_element_function update_page update_page_tag

### Constants

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)

### Public Instance methods

evaluate_remote_response()

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.

form_remote_for(object_name, *args, &proc)

Alias for remote_form_for

form_remote_tag(options = {}, &block)

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 -%>

link_to_remote(name, options = {}, html_options = {})

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.

observe_field(field_id, options = {})

Observes the field with the DOM ID specified by `field_id` and calls a callback when its contents have changed. The default callback is an Ajax call. By default the value of the observed field is sent as a parameter with the Ajax call.

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. The default is to send the key and value of the observed field. Any custom expressions should return a valid URL query string. The value of the field is stored in the JavaScript variable `value`.

Examples

      :with => "'my_custom_key=' + value"
      :with => "'person[name]=' + prompt('New name')"
      :with => "Form.Element.serialize('other-field')"

Finally

      :with => 'name'

is shorthand for

      :with => "'name=' + value"

This essentially just changes the key of the parameter.

`: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.

observe_form(form_id, options = {})

Observes the form with the DOM ID specified by `form_id` and calls a callback when its contents have changed. The default callback is an Ajax call. By default all fields of the observed field are sent as parameters with the Ajax call.

The `options` for `observe_form` are the same as the options for `observe_field`. The JavaScript variable `value` available to the `:with` option is set to the serialized form by default.

periodically_call_remote(options = {})

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.

remote_form_for(object_name, *args, &proc)

Works like form_remote_tag, but uses form_for semantics.

remote_function(options)

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>

submit_to_remote(name, value, options = {})

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`.

update_element_function(element_id, options = {}, &block)

Method to execute an element update using Prototype. DEPRECATION WARNING: This helper has been depercated; use RJS instead. See ActionView::Helpers::PrototypeHelper::JavaScriptGenerator::GeneratorMethods for more information.

update_page(&block)

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.

update_page_tag(html_options = {}, &block)

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.

### Protected Instance methods

build_callbacks(options)
build_observer(klass, name, options = {})
method_option_to_s(method)
options_for_ajax(options)

[Validate]