It is a good practice to use an empty alt attribute for images that don't need or don't have a text description. This is done by setting an empty alt attribute :
<img alt=""...
However in thymealf, when using a dynamic alt text that resolves to something null or empty, the attribute is removed altogether :
<img th:alt="${media.altText}"...
Is there an elegant way to solve this issue ?
The only option here would probably be something like this:
<img th:if="${#strings.isEmpty(media.altText)}" alt="" ... />
<img th:unless="${#strings.isEmpty(media.altText)}" th:alt="${media.altText}" ... />
It does mean duplicating your image tags, which may or may not work for you but it should solve the empty alt tag problem. (You could probably add it to a fragment that you include which would solve the code duplication aspect at least.)