MyFaces 2.0 AJAX API extension proposal
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Key: MYFACES-2174
URL: https://issues.apache.org/jira/browse/MYFACES-2174
Project: MyFaces Core
Issue Type: Sub-task
Components: JSR-314
Affects Versions: 2.0.0-alpha
Environment: browser independent javascript
Reporter: Ganesh Jung
JSF AJAX as defined in the spec is lacking several features that are needed to
make up for a good AJAX experience. They would be easy to implement, because
the underlying J4Fry AJAX already supports them, so we'd only need to pass the
parameters from the JSR 314 AJAX API to the implementation. Though these are
extensions to the specs I recommend implementing them along with the MyFaces
2.0 AJAX core because they are hardly separable from the standard xhr request
and callback. Please comment on these extensions.
Here's the proposal for MyFaces 2.0 extensions to the JSR 314 AJAX API:
current API:
j4fry.faces.Ajax.ajaxRequest(this, event, {execute: (componentIds), render:
(componentIds)}
proposed API (all additional attribute are optional, so spec conformant
requests are still supportet):
j4fry.faces.Ajax.ajaxRequest(this, event, {execute: (componentIds), render:
(componentIds), disable: (keywords/componentIds), submit: (componentsIds),
queuesize: (int), loadingbar: (image url), errorlevel: (warning/error/fatal),
execbefore: (JS function), execafter: (JS function)})
And here is what the additional attributes are meant to do:
disable:
If the JSF developer wants to stop the user from givin additional input on
certain or all components before the response is complete he can set this
attribute. The designated components are disabled before the xhr request is
made and only become reenabled when the xhr callback completes. It's impossible
to implement this based on the specs API because there is no means to know at
which point the callback completes.
Possible values are:
Either a keyword from this list
* ALL (all elements)
* BUTTON (all input-elements with type 'button')
* SUBMIT (all input-elements with type 'submit')
* RESET (all input-elements with type 'reset')
* TEXT (all input-elements with type 'text')
* RADIO (all input-elements with type 'radio')
* CHECKBOX (all input-elements with type 'checkbox')
* SELECT (all select-elements)
* TEXTAREA (all textarea-elements)
* A (all hyperlinks - a-elements)
or the component id's of the elements to disable.
Defaults to 'SUBMIT, RESET, BUTTON, A'.
submit:
If set, the PPS (partial page submit) feature becomes active. Only the elements
numbered in this attribute will become submitted and only the corresponding
components will be called for apply request values and update model.
queuesize:
The desired size of the request queue. For most applications it makes sense to
set this to 1. Default is unlimited.
loadingbar:
During AJAX requests applications usually want to make visible some animated
gif like a turning snake or similar. In this attribute the developer can pass
the id of an img element. The img should be set to visibility: hidden when the
page builds up and will be set to visibility: visible during the request.
Again, it's impossible to implement this based on the specs API because there
is no means to know at which point the callback completes.
errorlevel:
Will bring up an alert box displaying Javascript errors. This is very helpful
for debugging purposes. Possible level values are: warning, error, fatal, none.
default is 'none'.
execbefore:
Javascript code that will be executed before the xhr request. Setting this
attribute is actually very similar to writing the script code right in front of
the actual AJAX call, but there is a slight difference: Exceptions or return
false in front of the AJAX call will hinder the request. Execbefore will catch
exceptions and only display them when errorlevel <= warning and return false
will have no effect.
execafter:
Javascript code that will be executed after the xhr callback has returned. In
many cases scripts are only to be called after the callback has returned and
the manipulations of the DOM tree are finished. This attribute is a hook for
these scripts. Execafter will catch exceptions and only display them when
errorlevel <= warning.
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