Can jstl check if attribute has been added to the model?

Is it possible to check if an attribute has been added to the model?

//in the controller teh variable is not always added
//
model.addAttribute("variable", myVariable);

and in the jsp something like this

<c:choose>
    <c:when test="${variable is present}">
        Not present
    </c:when>
    <c:otherwis开发者_运维百科e>
        Present
    </c:otherwise>
</c:choose>

Thanks

---

JSTL/EL cannot check if an attribute has been added to the model. For that you need to implement an observer/observable yourself.

EL can however check if a bean property or a map value is not null or empty.

<c:when test="${not empty bean.property}">

---

<c:when test="${not empty map.key}">

See also:

• Java EE tutorial - Overview of EL operators
• Java EE tutorial - Examples of EL expressions

---

You can check if the attribute is empty

<c:if test="${not empty post}">
   <h3>${post.title}</h3>   
</c:if>