Model Binding and Calculated Field Syntax for "class" Attribute

Question

Hi,
I tried to use the calculated field syntax from SAP UI5 to change the CSS class attribute of an element based on some model property, i.e., I wanted to change the class in the corresponding formatter function based on the currently bound value. However, my formatter function is not called. When I use the same syntax on a text attribute, it works.
I also tried to use normal property binding, but it did not work on the class attribute either (it just put class="{property}" in the rendered HTML).
Is there anything I missed or is it just not possible to use property binding and calculated field syntax for class attributes? Did anybody try something like this before?
I think it is a standard use case to change the CSS class based on some model property. So, if anybody knows how to do that, could you give a short example?
Best regards
Svenja

Answer 1

They have a class property. At least, I can do the following in an XML view:
<Button
              icon="sap-icon://add"
              press="onButtonPress"
              class="my-button-class" />
I would expect the following to work as well, but for me it did not:
<Button
              icon="sap-icon://add"
              press="onButtonPress"
              class="{/customClass}" />
This renders the following HTML (cropped to the important parts):
<button type="button" class="sapMBtn {/customClass}">
</button>
It seems like the class attribute is something special although I don't see a reason why. Other HTML templating engines, for example, support things like that.