Zone-Update inside a form inside a block (with generated ids) not working
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Key: TAP5-1746
URL: https://issues.apache.org/jira/browse/TAP5-1746
Project: Tapestry 5
Issue Type: Bug
Components: tapestry-core
Affects Versions: 5.3
Reporter: Christian Riedel
Priority: Critical
Zone-Updates are not working under certain conditions when being rendered
inside a block.
If an outer zone receives a zone-update the components inside the content of
the delegated block will have generated ids:
{{noformat}}
<t:zone t:id="outerZone">
<t:delegate t:to="block" />
</t:zone>
{{noformat}}
--> after a zone-update the "block" property resolves to the following block:
{{noformat}}
<t:block t:id="editBlock">
<t:form t:id="editForm">
<t:select t:id="updateSelectBox" t:model="values"
t:value="selected" t:zone="updateZone" />
<t:zone t:id="updateZone">
<t:select t:id="theOtherValue" t:model="otherValues"
t:value="other" blankOption="never" />
</t:zone>
</t:form>
</t:block>
{{noformat}}
The select component "updateSelectBox" won't find the zone "updateZone" since
the real clientId has a randomly generated number appended.
To circumvent this feature one can write a getter to obtain the generated id
each time the block renders:
{{noformat}}
<t:select t:id="updateSelectBox" t:model="values"
t:value="selected" t:zone="prop:updateZoneId" />
{{noformat}}
{{noformat}}
public String getUpdateZoneId() {
return updateZone.getClientId();
}
{{noformat}}
However, this won't work as expected, either.
Firstly because the clientId is always null at that point. It's being called
before the zone's beginRender method is invoked.
Secondly because you need this client id in the event handler as well. Even if
you'd be able to get the id at this point, the execution of the processReply
method in tapestry.js will fail because it can't find the zone. The id has been
generated once more and is not yet known to the client:
{{noformat}}
@OnEvent(component = "updateSelectBox", value =
EventConstants.VALUE_CHANGED)
void onValueSelected() {
// this will also fail on the client side
ajaxResponseRenderer.addRender(getUpdateZoneId(), updateZone);
}
{{noformat}}
Now what I found being the only workaround is to store the client id once it's
generated, i.e. when the block renders the first time.
But as I stated earlier the id is null before beginRender is called. So another
workaround must be applied:
Switch the order of the components:
{{noformat}}
<t:block t:id="editBlock">
<t:form t:id="editForm">
<t:zone t:id="updateZone">
<t:select t:id="theOtherValue" t:model="otherValues"
t:value="other" blankOption="never" />
</t:zone>
<t:select t:id="updateSelectBox" t:model="values"
t:value="selected" t:zone="prop:updateZoneId" />
</t:form>
</t:block>
{{noformat}}
Now that the "updateZone" renders before the "updateSelectBox",
"prop:updateZoneId" is able to return the correct id.
Please make the first example work! It should not be necessary to deal with the
generated ids. Tapestry.js should implement some magic-code to find out the
correct zone if "updateZone" is referenced in the template. Since all
components within the same block have the same generated value appended it
might actually be possible to find the correct zone.
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