JSTL conditional check

Question

On my current page I am using JSTL to check if data is available for my form. Problem I am facing is "if there is no data I am not seeing the text fields either". I can solve it using and tags but that would entail lot of if else if else kind of code all through the page. Can anyone suggest me a better cleaner solution to this problem?

<c:if test="${salesData!=null}">
  <c:if test="${fn:length(salesBundle.salesArea) > 0}">
  <input type="text" id="sales_area" class="salesManagerStyle">
  </c:if>
</c:if>

Federate

Answer 1

You can have multiple conditions in a test.

<c:if test="${salesData != null && fn:length(salesBundle.salesArea) > 0}">
    <input type="text" id="sales_area" class="salesManagerStyle">
</c:if>

But you can also use the empty keyword to do both a nullcheck and lengthcheck.

<c:if test="${not empty salesData.salesArea}">
    <input type="text" id="sales_area" class="salesManagerStyle">
</c:if>

That's the best what you can get, now. If you need to reuse the same condition elsewhere in the page, then you could also save it by <c:set>.

<c:set var="hasSalesData" value="${not empty salesData.salesArea}" />
...
<c:if test="${hasSalesData}">
    <input type="text" id="sales_area" class="salesManagerStyle">
</c:if>
...
<c:if test="${hasSalesData}">
    Foo
</c:if>

Dynasty

BalusC, Thanks for the reply. <c:set idea sounds perfect :-) Let me try this real quick – Federate

Actually just realized, this is still the same c:if. To implement c:choose we still have to go through same amount of statements. Right? – Federate

Yes, basically. That's the payoff. If you were using a MVC framework like JSF, then you could save the <c:if>s by using the rendered attribute on the components. E.g. <h:inputText value="#{bean.value}" rendered="#{hasSalesData}" />. – Dynasty

Thanks BalusC. Anything similar to rendered in Spring MVC? Also can I use c:choose like <c:choose test="${hasSalesData}"> ??? – Federate

I don't do Spring MVC, so I can't tell from top of head. As to the <c:choose>, the condition has to go in a nested <c:when test="${hasSalesData}">. See also this question which I by coincidence also answered today: https://mcmap.net/q/206175/-how-do-i-do-the-equivalent-of-a-java-if-else-block-using-jstl-duplicate You can have more than one <c:when>s in a single <c:choose>, for the case you want an if-elseif-elseif-else. – Dynasty

Answer 2

I try to put as little logic as possible in my web pages,

"The interface tier is relatively free of application processing; windows or web pages forward task request to middle tier" Graig Larman, Applying UML and Patterns third Edition page 575 - Information Systems: The classic Three-tier architecture.

Also do the control/validation at the client level before persisting the data...but I guess if it is legacy and web pages are the only things you can touch ...this makes sens

Kyungkyushu