Add attributes after replace

[NielsNet]

Currently (Thymeleaf 3.0.0) there does not seem to be a way to add attributes to a tag that is replaced.
E.g. when having a fragment called testFrag in a file /test/fragments:

<div class="default-class">
   Hello World!
</div>

and using this:

<div th:replace="/test/fragments::testFrag" th:classappend="append-me"></div>

I'd expect the following:

<div class="default-class append-me">
    Hello World!
</div>

However, the actual output is

<div class="default-class">
    Hello World!
</div>

I was wondering if I just missed out a way to do this with standard thymeleaf or if it might be a planned feature.

[danielfernandez]

This is the expected behaviour of th:replace. This attribute replaces the tag it lives in with the one selected in the expression, it does not merge it or peform any similar operation. So a th:classappend in the tag that contains that th:replace will be simply lost.

In order to do a merge operation like the one you need, you'd have to do something more specific, like for example:

<div th:fragment="testFrag(classapp)" class="default-class" th:classappend="${classapp}">
   Hello World!
</div>

And then:

<div th:replace="/test/fragments :: testFrag ('append-me')"></div>

[NielsNet]

This would mean that one would have to define a parameter for any attributes to add on the replaced fragment. Is there a way to do something like a merge or would that require a custom dialect?
Imagine you wanted to use some data tags, the classes and some more from the replaced tag on its replacement. It would become a mess with that many parameters.

[Simsteve7]

Is there any update on the question of @NielsNet? It would be really nice to replace fragments and keep the attributes.

[ygogolitsyn]

Have been asked to look at this issue by Code Triage.
Would an introduction of a completely new attribute that would do what th:relplace does, but keep the attributes be acceptable? Something like th:replacewithattr?

[srinath-gs]

Have been asked to look at this issue by Code Triage. Would an introduction of a completely new attribute that would do what th:relplace does, but keep the attributes be acceptable? Something like th:replacewithattr?

is there any update on this th:replacewithattr ? @danielfernandez