Hi Finn,
Thanks for your thorough review. Comments inline.
On 14/02/2010 08:35 AM, Finn Bock wrote:
It is good to see that ajax will get some attention. I have a few questions:
1) My guess is that the inclusion of my-page.js does not happen
automatically. I will have to add it in onInit or the page ctor:
getHeadElements().add(new JsImport("/mycorp/js/my-page.js");
For #1 yes, Click provides a way to invoke a page method and nothing more. It turns the Page into a
Controller with methods that the browser can invoke. While simple and mechanic it could work well
for adhoc GET requests.
For #2 or #3 the Control/Behavior can include its dependencies, including a
default JS template.
ClickClick is based on #2 and you can see from the example below only Java code is necessary to
change the label:
Source:
http://code.google.com/p/clickclick/source/browse/trunk/clickclick/jquery-examples/src/net/sf/clickclick/examples/jquery/page/ajax/TextDemo.java
Live Demo: http://clickclick-jquery.appspot.com/ajax/text-demo.htm
The JQActionLink control embeds a JQHelper object which includes all dependencies and a default JS
Velocity template. The template is JavaScript/jQuery code that can be customized if needed.
ClickClick has three Helpers that extend JQHelper and uses different templates to perform different
operations. To give you an idea there is a helper for forms, auto complete and polling.
2) In the "1. Ajax aware Page methods" proposal you write that no
other page event methods will be called, but I think some kind of
security check will be needed, so onSecurityCheck() should perhaps be
called.
Yes you are right, onSecurityCheck should still be fired. I've updated the WIKI.
3) What does the "click" string passed to the AjaxBehaviour ctor mean.
Is it the event that is bound to in jquery?
Yes it is the event. We could make the event argument optional and let the Behavior define a default
event it will bind to.
4) How does it handle multiple dom updates? Taconite?
For jQuery I think the taconite plugin is pretty good. I'm not sure if other JS frameworks have
plugins for taconite though.
From Click's perspective it only knows about the Partial object that it streams back to the client.
Whether a Partial implementation supports multiple DOM updates will be determined by the client-side
technology used.
My reaction so far:
I feel somewhat put off by the suggestion that even the simplest ajax
example requires that I write javascript. Even more so when the
javascript isn't easy to maintain:
a) id's must match between java and javascript.
b) duplicate target id (mylink in the example)
c) hardcode url of the page in javascript.
I've not done a good job explaining this in the proposal, but the example JavaScript code is what a
jQuery based implementation should *generate*. Here is what a generic jquery based template could
look like:
// $selector is a variable passed to the template from Click
$('$selector').bind('$event', makeRequest);
function makeRequest(event) {
//grab ID parameter from the element which is passed to server
var sourceId = $(this).getAttribute("id");
// $path is passed to the template from Click
$.get("$path", {
sourceId: 1, // Parameter 1 -> ID of element event occurred on
event: event.type // Parameter 2 -> Event that was fired
});
}
If jQuery's Taconite is used, there is no need for a "success" JS handler here, it will be taken
care of by the Partial response:
public class MyPage {
private Field field = new TextField("field");
private Field copy = new TextField("copy");
public void onInit() {
// Label will be the target. The ID is defined only once
label.setId("labelId");
AjaxBehavior behavior = new AjaxBehavior( JQueryEvent.KEYPRESS ) {
public Partial onEvent(Control source, Event event) {
// Taconite extends Partial
Taconite partial = new Taconite();
// Copy field value
copy.setValue(field.getValue());
// Inform Taconite to replace copy field
partial.replace(copy);
return partial;
}
}
f.addBehavior(behavior);
}
}
I think the target dom (or control) element(s) must be named when the
partial is created, otherwise it is too hard to read and understand an
ajax click application.
Could you expand on this? I would imagine that if Taconite is used it won't be necessary to specify
the target.
As far as I understand the proposals, I favor #3 without support for
#1. #1 is too simple IMO.
Noted we could leave #1 out, however #1 could be useful for normal (non-ajax)
requests as well though.
Hope this clears the issues raised. I'd really like to get this Ajax stuff right so keep the
comments coming.
kind regards
bob
