问题
Is there a simple way in thymeleaf to show the content of an attribute property if the property and the attribute exist? If there's an attribute "error" with a property "summary" in my html page, I'd like to show it:
<span th:text="${error.summary}">error summary</span>
If there is no attribute "error" the following error is raised:
org.springframework.expression.spel.SpelEvaluationException: EL1007E:(pos 0): Field or property 'summary' cannot be found on null
Currently I'm using the following approach, which just seems too complicated.
<span th:if="${error != null and error.summary != null}"><span th:text="${error.summary}">error summary</span></span>
Is there a simpler way to achieve that?
回答1:
Sure! Since the processor associated with the th:if attribute has a higher precedence than the one associated with the th:text attribute, it will be evaluated first. Thus you can write:
<span th:if="${error != null && error.summary != null}" th:text="${error.summary}">Static summary</span>
You could even shorten it using:
<span th:text="${error?.summary}">Static summary</span>
But I think in this case, whether the summary exist or not, the span tag will be created, which is a bit ugly.
See more info about conditional expressions here.
来源：https://stackoverflow.com/questions/21529085/thymeleaf-show-text-if-the-attribute-and-property-exists