Shared event handler for XML views with different controllers - event-handling

Question

Given two XML Views:
<mvc:View
controllerName="my.namespace.controller.First"
xmlns:mvc="sap.ui.core.mvc"
xmlns="sap.m">
<Button press=".onBtnPress" />
</mvc:View>
<mvc:View
controllerName="my.namespace.controller.Second"
xmlns:mvc="sap.ui.core.mvc"
xmlns="sap.m">
<Button press=".onBtnPress" />
</mvc:View>
As expected, the press event is handled by First.controller.js or Second.controller.js.
Instead of duplicating the event handler code or implementing handlers in each Controller to chain/hand off the work, I want to declare a shared event handler.
According to docs this should be possible, using a naming convention for the handler:
Names starting with a dot ('.') are always assumed to represent a method in the controller.
Names containing a dot at a later position are assumed to represent global functions and are resolved by calling jQuery.sap.getObject with the full name.
So I change the handler and declare a shared object, like so:
First.view.xml:
<Button press="my.namespace.Shared.onBtnPress" />
Shared.js:
jQuery.sap.declare("my.namespace.Shared");
my.namespace.Shared = (function() {
var onBtnPress = function() {
console.log("button pressed");
};
return { onBtnPress : onBtnPress };
}());
Warning logged (debug sources) during view initialisation:
sap.ui.core.mvc.XMLView#__xmlview1: event handler function "my.namespace.Shared.onBtnPress" is not a function or does not exist in the controller. -
Calling jQuery.sap.getObject("my.namespace.Shared") yields undefined
Same issue when using sap.ui.define to make the object known.

Answer 1

Since UI5 1.69, it has become easier to share JS modules in XML view and fragment.doc
Here is an example: https://embed.plnkr.co/5G80I5HWObCuM5cG
<mvc:View controllerName="..."
xmlns:mvc="sap.ui.core.mvc"
xmlns="sap.m"
xmlns:core="sap.ui.core"
core:require="{ onButtonPress: 'my/shared/onButtonPress' }">
<Button text="Press" press="onButtonPress" />
</mvc:View>
As we can see, each button displays a different message depending on the view, even though the handler itself isn't included in the controller definition.
The this context is still the controller instance as documented in the topic Handling Events in XML Views:
As long as no event handler parameters are specified and regardless of where the function was looked up, it will be executed with the controller as the context object (this).

Answer 2

Your shard object looks weird
Try something like this:
sap.ui.define([], function() {
return sap.ui.base.Object.extend("my.namespace.Shared", function() {
onBtnPress : function() {
console.log("button pressed");
}
};
});
Also remember to put the object in the right directory.

Answer 3

I was able to copy-paste your sap.ui.define and verified it was created correctly jQuery.sap.getObject.
Make sure that your sap.ui.define has been called prior to your view being rendered.
You can set a breakpoint in the XMLTemplateProcessor where the event callbacks are handled for XML views for further debugging/timing issues.
If you look in the _resolveEventHandler function it should take you here which will perform the jQuery.sap.getObject.