How to do if-else in Thymeleaf?
if-statement, java, jsp, jstl, thymeleaf
Solution
Thymeleaf has an equivalent to `<c:choose>` and `<c:when>`: the `th:switch` and `th:case` attributes introduced in Thymeleaf 2.0.
They work as you'd expect, using `*` for the default case:
<div th:switch="${user.role}">
<p th:case="'admin'">User is an administrator</p>
<p th:case="#{roles.manager}">User is a manager</p>
<p th:case="*">User is some other thing</p>
</div>
See this for a quick explanation of syntax (or the Thymeleaf tutorials).
Disclaimer: As required by StackOverflow rules, I'm the author of Thymeleaf.
Problem
What's the best way to do a simple `if`-`else` in Thymeleaf? I want to achieve in Thymeleaf the same effect as ``` <c:choose> <c:when test="${potentially_complex_expression}"> <h2>Hello!</h2> </c:when> <c:otherwise> <span class="xxx">Something else</span> </c:otherwise> </c:choose> ``` in JSTL. What I've figured so far: ``` <div th:with="condition=${potentially_complex_expression}" th:remove="tag"> <h2 th:if="${condition}">Hello!</h2> <span th:unless="${condition}" class="xxx">Something else</span> </div> ``` I don't want to evaluate `potentially_complex_expression` twice. That's why I introduced local variable `condition`. Still I don't like using both `th:if="${condition}` and `th:unless="${condition}"`. An important thing is that I use two different HTML tags: let's say `h2` and `span`. Can you suggest a better way to achieve it?