Indeed I agree with Hugo.
I had this use case a couple of times and solved it in the same way as
Hugo did.
I also hoped there is an easier way to implement dependable selects,
using zones...
Also filling selects with objects is not really easy. I need to
implement a selection model and a value encoder.
I have the feeling that things are more complicated than they should be.
For example, it would be easier to add a select into my page and bind a
list with objects to it with setting the labelField and idField to
object properties.
So like this;
<select t:type="select" t:id="productSelect" model="productList"
labelField="name", idField="id" value="selectedProduct" />
I get the feeling that sometimes tapestry 5 is doing things to complicated.
Leon
Hugo Palma wrote:
Everything i used in the example is built into Tapestry except the
OnEvent mixin that is provided by the library
t5-components(http://87.193.218.134:8080/t5components/index.html).
The javascript stuff is part of prototype that is already bundled with
Tapestry.
James Hillyerd wrote:
Hugo,
That's a great example. I think this belongs on the Wiki!
Is the JSON stuff built into Tapestry, or do I need a third party
library
for that?
-james
On Tue, Dec 9, 2008 at 10:17 AM, Hugo Palma <[EMAIL PROTECTED]>
wrote:
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.
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