The prototype module is accessible via the webhelpers.rails module.
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 link_to_remote for documentation of options common to all Ajax helpers.
See also Scriptaculous for helpers which work with the Scriptaculous controls and visual effects library.
Links to a remote function
Returns a link to a remote action defined dict(url=url()) (using the url() 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 the update keyword.
Any keywords given after the second dict argument are considered html options and assigned as html attributes/values for the element.
Example:
link_to_remote("Delete this post", dict(update="posts",
url=url(action="destroy", id=post.id)))
You can also specify a dict for 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",
dict(url=url(action="destroy", id=post.id),
update=dict(success="posts", failure="error")))
Optionally, you can use the 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(word,
dict(url=url(action="undo", n=word_counter),
complete="undoRequestCompleted(request)"))
The callbacks that may be specified are (in order):
You can further refine success and failure by adding additional callbacks for specific status codes.
Example:
link_to_remote(word,
dict(url=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 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:
Periodically calls a remote function
Periodically calls the specified url every frequency seconds (default is 10). Usually used to update a specified div 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.
Create a form tag using a remote function to submit the request
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. 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=dict(action=url(
controller="some", action="place")))
By default the fall-through action is the same as the one specified in the url (and the default method is POST).
A submit button that submits via an XMLHttpRequest call
Returns a button input tag that will submit form using XMLHttpRequest in the background instead of regular reloading POST arrangement. Keyword args are the same as in form_remote_tag.
Returns a JavaScript function (or expression) that'll update a DOM element.
Example:
<% javascript_tag(update_element_function("products",
position='bottom', content="<p>New product!</p>")) %>
This method can also be used in combination with remote method call where the result is evaluated afterwards to cause multiple updates on a page. Example:
# Calling view
<% form_remote_tag(url=url(action="buy"),
complete=evaluate_remote_response()) %>
all the inputs here...
# Controller action
def buy(self, **params):
c.product = Product.find(1)
return render_response('/buy.myt')
# Returning view (buy.myt)
<% update_element_function(
"cart", action='update', position='bottom',
content="<p>New Product: %s</p>" % c.product.name) %>
<% update_element_function("status", binding='binding',
content="You've bought a new product!") %>
Returns a Javascript function that evals a request 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.
Returns the JavaScript needed for a remote function.
Takes the same options that can be passed as options to link_to_remote.
Example:
<select id="options" onchange="<% remote_function(update="options",
url=url(action='update_options')) %>">
<option value="0">Hello</option>
<option value="1">World</option>
</select>
Observes the field with the DOM ID specified by field_id and makes an Ajax call when its contents have changed.
Required keyword args are:
Additional keyword args are:
Additionally, you may specify any of the options documented in link_to_remote.
Like observe_field, but operates on an entire form identified by the DOM ID form_id.
Keyword args are the same as observe_field, except the default value of the with_ keyword evaluates to the serialized (request string) value of the form.
See the source for more information.