Prototype Class
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 page 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.
Initializing the Class
Initialize this class like any other class.
$prototype= new Prototype();
Then use any of the meber functions given below.
evaluate_remote_response()
Returns ‘eval(request.responseText)’ which is the JavaScript function that form_remote_tag can call in ['complete'] to evaluate a multiple update return document using update_element_function calls.
form_remote_tag($options)
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( array('url'=>$some_url) );
link_to_remote($name,$function,$html_options=null)
Returns a link to a remote action defined by options['url'] 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 either render_partial or render_partial_collection.
Example :
link_to_remote("Delete this post",array('url'=>$some_url."task=delete&id=".$some_id."'"));
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",array('url'=>$some_url."task=delete&id=".$some_id."'",'update'=array('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'].
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("Delete this post",array('url'=>$some_url."task=delete&id=".$some_id."'" , '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).
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 =null)
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.
- 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.
observe_form($form,$options=null)
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.
periodically_call_remote($options=null)
Periodically calls the specified url (options['url']) every options['frequency'] seconds (default is 10). Usually used to update a specified div (options['update']) with the results of the remote call. The options for specifying the target with :url and defining callbacks is the same as link_to_remote.
remote_function($options)
Returns the JavaScript needed for a remote function. Takes the same arguments as link_to_remote.
Example:
<select id="options" onchange="<?= remote_function(array('update' => 'options', 'url' => $some_url) ? >">
<option value="0">Hello</option>
<option value="1">World</option>
</select>
submit_to_remote($name,$value,$options=null)
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.
These functions are from JavaScriptGenerator class which was merged into prototype.
dump($javascript)
Writes raw JavaScript to the page.
ID($id,$extend=null)
Returns a element reference by finding it through id in the DOM. This element can then be used for further method calls.
Examples:
ID('blank_slate'); // => Will return $('blank_slate');
ID('blank_slate','show'); // => $('blank_slate').show();
alert($message)
Displays an alert dialog with the given message.
assign($variable,$value)
Assigns the JavaScript variable the given value.
call($function,$args = null)
Calls the JavaScript function, optionally with the given arguments.
delay($seconds=1,$script='')
Executes the content of the block after a delay of seconds.
hide($ids)
Hides the visible DOM elements with the given ids.
insert_html($position,$id,$options_for_render=null)
Inserts HTML at the specified position relative to the DOM element identified by the given id.
position maybe one of:
- top
HTML is inserted inside the element, before the element’s existing content. - bottom
HTML is inserted inside the element, after the element’s existing content. - before
HTML is inserted immediately preceeding the element. - after
HTML is inserted immediately following the element.
//Insert the rendered 'navigation' partial just before the DOM
//element with ID 'content'.
insert_html('before','content',array('partial'=>'navigation');
redirect_to($location)
Redirects the browser to the given location.
remove($ids)
Removes the DOM elements with the given ids from the page.
replace($id,$options_for_render=null)
Replaces the "outer HTML" (i.e., the entire element, not just its contents) of the DOM element with the given id.
replace_html($id,$options_for_render=null)
Replaces the inner HTML of the DOM element with the given id.
select($pattern)
Returns a collection reference by finding it through a CSS pattern in the DOM. This collection can then be used for further method calls.
Examples:
select('p') // => $$('p');
show($ids)
Shows hidden DOM elements with the given ids.
toggle($ids)
Toggles the visibility of the DOM elements with the given ids.