Here's how i'm doing this now:
On the source select i'm using the OnEvent mixin to fire the change event:
<select t:id="operator" t:type="select" t:mixins="commons/onEvent"
t:event="change" t:onCompleteCallback="onCompleteOperatorChange" .../>
The event listener method is then responsible for querying the database for
the value to be set in the destination select:
@OnEvent(component = "operator", value = "change")
public JSONArray onChangeOperatorEvent(String value) {
JSONArray jsonArray = new JSONArray();
for (Plaza plaza : getDestinationSelectValues(value)) {
JSONObject jsonObject = new JSONObject();
jsonObject.put("value", plaza.getId());
jsonObject.put("label", plaza.getDescription());
jsonArray.put(jsonObject);
}
return jsonArray;
}
Finally, the onCompleteOperatorChange javascript function has to parse the
return JSON and update the select input options:
function onCompleteOperatorChange(response) {
selectElement = $("entryPlaza");
responseJSON = response.evalJSON();
while (selectElement .options.length > 0) {
selectElement .options[0] = null;
}
for (index = 0; index < responseJSON .length; index++) {
selectElement.options[index] = new Option(responseJSON
[index].label, responseJSON [index].value);
}
Tapestry.ElementEffect.highlight($("entryPlaza"));
}
It would make things a little easier if the selects weren't inside a form
because then my event listener method could return the component instance
itself and then on the client i would just have to replace the current
element with the new rendered one.
On Sun, Dec 7, 2008 at 10:46 PM, Hugo Palma <[EMAIL PROTECTED]>
wrote:
I'm already using the OnEvent component. Still, because the model of the
select list i want to update is calculated server-side i need to pass it
in
json to the client, parse it again in javascript and then update the
select
input. This does work but i feel that there should be a simpler way of
doing
this, maybe using zones.
thermus wrote:
I'm a Tapestry novice, but you may want to have a look at
http://code.google.com/p/tapestry5-components/ t5components . It allows
you
to add a mixin to components to respond to an OnChange event with AJAX
(see: http://87.193.218.134:8080/t5c-demo/oneventpage this and
http://87.193.218.134:8080/t5components/t5c-commons/ref/org/apache/tapestry/commons/mixins/OnEvent.html
this for details). You could then change the data model for the other
select component with a tiny bit of JavaScript in the onCompleteCallback
function.
I'm curious how a Tapestry expert would handle it.
HugoPalma wrote:
I have a very usual use where in a form i have two selects, and when the
user selects a value on one the values on the second should be filtered
accordingly.
As the Select component doesn't support ajax out-of.the-box i see myself
forced to implement a lot of plumbing and javascript stuff.
Still, i feel that this kind of use case should be much easier to
implement.
Maybe i'm missing something.
I'd like to hear some ideas about how u would handle this.
Thanks.
