Page.getLevelPage(int)

Hi,

In my presentation WCB I am building some pageparts for displaying the navigation on the website. I want the highest level to be displayed horizontally and the second highest level to be displayed vertically at another place of the HTML, so I cannot do some recursive solution.

No, I found out I can do ${page.level1Page} to get the highest level for my horizontal menu structure. I found out about a Page.getLevelPage(int) method, but how can I use this from my second level navigation pagepart?

/arnoud

Hi Arnoud,

In the JSP expression language it is not possible to call a method that requires arguments, so you must use a scriptlet for this. Inside a scriptlet, you can use the Java syntax.

The code snippet below should help you build what you want:

<%@ page import="nl.gx.webmanager.cms.core.Page" %>
<%@ taglib uri="http://java.sun.com/jstl/core" prefix="c" %>

<c:set var="currentPage" value="${presentationcontext.page}" />
<c:set var="level1Page" value="${currentPage.level1Page}" />

<%-- c:set var="level2Page" ... --%>
<%
Page currentPage = (Page)pageContext.getAttribute("currentPage");
Page level2Page = currentPage.getLevelPage(2);
pageContext.setAttribute("level2Page", level2Page);
%>

<c:set var="subPages" value="${level2Page.current.subPagesWithCurrent}" />

Gr,
Mark

I'd strongly discourage using scriplets, especially when there are other, better solutions. One of them is writing your own taglib, or just using the following code:

<c:set var="currentPage" value="${presentationcontext.page}" />
<c:set var="myParents" value="${currentPage.parents}" />

<c:if test="${not empty level1Page.current}"
<c:set var="level2Pages" value="${level1Page.current.subPages}" />

<c:forEach var="level2page" items="${level2Pages}">
<c:if test="${not empty level2page.current}">
<c:if test="${wmfn:contains(level2page, myParents) || level2page == currentPage}">
<c:set var="activeLevel2Page" value="${level2page}" />
</c:if>
</c:if>
</c:forEach>

</c:if>
</c:if>

Hi Jetske,

I agree in that using scriptlets should be discouraged in general. They can easily clutter your code and things are often cleaner when they're avoided.

However, when I compare your snippet to mine, your snippet is double the size and it's less clear what it's doing when you read it. I argue that this case is an exception to the general rule of avoiding scriptlets.

Gr,
Mark

hi,

Thank you! Both solutions are working. Are you clear on what solution is the preferred one?

/arnoud

I have to agree with Mark here. The core problem is that the "scriptlets are bad" rule is a crude and inaccurate simplification of the more general rule of thumb: "Avoid mixing big chunks of processing code in your presentation code". It doesn't matter so much whether the code is JSP tags or scriptlet code. This thread here is a good example of how the "scriptlets are bad" rule is wrong. The solution presented here using a scriptlet is shorter and easier to understand and maintain. It's a clear winner in my opinion.

There are things which JSP tags are not good for, and this is one of them.

As for writing a taglib, it just another case of weighing up the cost (time + effort, extra code) of doing that against the gains (reusability, code organisation). Unless you plan to reuse that snippet of code later, I would probably just go for the cheapest solution instead of paying extra cost. You can pay the extra cost later to make a tablib if you really need to.

cheers,

--
Simon

If I'm not mistaking, the "getLevelPage(int)" method is in the API, isn't it? I vaguely recall stumbling upon it. So calling it using a scriptlet shouldn't cause any future problems. I agree with Simon that using the scriptlet seems the more elegant of the two in this case.

I'll keep on telling my students "scriptlets are bad, mmkay?" though. Easier to memorize than "Avoid mixing big chunks of processing code in your presentation code, mmkay?".

Greetings,

Patrick