A jstl variable is set in request scope in a jsp
<c:set var="name" value="Tiger" scope="request" />
This variable is accessed from a jspf included to this jsp. Now, is there any difference in accessing the variable in these two ways ?
1) <c:out value="${name}" />
2) <c:out value="${requestScope.name}" />
When to use requestScope ?
You use requestScope when you absoluetely want your object to come from the request, and not from the page, session or application scope. Inded, using ${name} will search for a name attribute in the page, then in the request, then in the session, then in the application.
Let's say that some other code in the JSP set a name attribute in the page scope. But you want to access the name in the request: you're forced to use requestScope.
Let's say the session might have a name attribute. Not using requestScope.name would return the session-scoped name if the JSP forgot to set the name attribute in the request scope.
If the goal of the JSP fragment is to access something set in the enclosing JSP, maybe this JSP fragment should be a JSP tag, and you should pass the name as an argument to this tag.
Within my research (I am also new one for jstl),
request scope can set values to request page from response page for example assume that we have a page called index.jsp and its action page is index_action.jsp
if we, set values to the action page
<c:set var="nme" scope="request" value="Janaka aravinda"/>
<% request.getRequestDispatcher("index.jsp").forward(request, response); %>
(// I created nme variable and set its value as Janaka aravinda. and back to reload request page(index.jsp) )
Now we can call nme in index.jsp nme variable as follow
Request value
<c:out value="${nme}"/>
Related
I'm using facelets (JSF2.1) and I'm trying to do something like:
<c:forEach var="domainObject" items="#{MB.listOfDomainObjects}">
<sec:authorize access="hasPermission(#domainObject,'PERMISSION_X')">
hello world
</sec:authorize>
</c:forEach>
I've tried changing #domainObject by #domainObject, #{domainObject}, $domainObject and a lot of other combinations with the same result: domainObject is not processed correctly. Sometimes I get an error saying the page cannot be constructed, others domainObject is null.
It's like the scope where the tag c:forEach puts the variable domainObject is not scanned by sec:authorize to find it.
I've tried also to force the use of a scope using the tag <c:set ... scope="view"/>. I've also tried to use <ui:repeat> with the same results, but considering the tag sec:authorize is a jstl one, I suppose is executed in build time (like c:forEach) and not in render time (like ui:repeat), so I think I must use c:foreach and not ui:repeat.
Any chance to solve my problem?
I have in my JSP page code like this:
<spring:url value="" var="url"/>
EN
And issue is that parameter url in link is always set to empty String.I would expect that if I type url like localhost:8080/test the url variable will hold this value and it will be replaced in link so it would look like /change_locale?locale=EN¤t=test. However it is always generated like /change_locale?locale=EN¤t=.What I am doing wrong? Best regards
In
<spring:url value="" var="url"/>
Your value value is the empty String. Because of this, the URL is relative.
Spring uses UrlTag to construct the value from a <url> tag. You'll want to take a look at its createUrl method in the source code if you're curious.
In this case, it will generate a value that is the empty String and store it in a page scope attribute named url. That's what you get when rendering
${url}
I am using Spring MVC. There is a requirement that some user selections remain globally and always in the url parameter. I might also be able to remove it with code at will.
Is there something like Persistent Page Data(like in Tapestry http://tapestry.apache.org/persistent-page-data.html) for Spring MVC.
A link to a similar quesion thats unanswered: http://osdir.com/ml/java.appfuse.user/2005-08/msg00507.html
Thanks
Update
Eventually I used a simple technique, where:
1. I would capture the current page url with query paramters.
2. Add or replace the new parameters into this url.
<c:set var="contextPath" value="${pageContext.request.contextPath}"></c:set>
<c:set var="servletPath" value="${requestScope['javax.servlet.forward.servlet_path']}"></c:set>
<c:set var="currentPath" value="${contextPath}${servletPath}"></c:set>
ageone
where replaceUrlParameter() uses regex to replace or add the query parameter.
Keep this parameters in session and write the Servlet Filter that would add them to any request or would modify request URL so they are visible in URL.
I am using Spring 2.5 in my application. In the view I have main jsp in which I have included another jsp. I have declared a variable using c:set tag in main jsp which I can not access inside the jsp. Below is code
main.jsp
<c:set var="hPediquestStudy"><spring:message code="study.hpediquest.mapping" /></c:set>
<c:set var="currentStudy" value='<%=(String)session.getAttribute("currentStudy")%>'/>
<html>
<head>
</head>
<body>
<c:if test="${currentStudy eq hPediquestStudy}">
Variables are equal
</c:if>
<c:if test="${currentStudy ne hPediquestStudy}">
Variables are not equal
</c:if>
<jsp:include page="/WEB-INF/jsp/included.jsp"></jsp:include>
</body
</html>
included.jsp
<c:if test="${currentStudy eq hPediquestStudy}">
hPediquestStudy Variable is accessible
</c:if>
<br/>currentStudy : ${currentStudy}
<br/>hPediquestStudy : ${hPediquestStudy}
I am getting output
Variables are equal
currentStudy : hPediquest
hPediquestStudy :
Why on main jsp both values are equal while in included jsp I dont see its value?
Why currentStudy displays its value inside the included jsp?
is there any solution which helps me to access the variable set in the parent jsp ans can be accessed in the included jsps?
I can see the value of hPediquestStudy value if I set that variable in included jsp like in main jsp. But I dont want to set it every time when I include the jsp. Please help
Why on main jsp both values are equal while in included jsp I dont see its value?
Because <c:set> by default stores them in the page scope.
Why currentStudy displays its value inside the included jsp?
Because it's available as session attribute as well.
is there any solution which helps me to access the variable set in the parent jsp ans can be accessed in the included jsps?
You need to set the scope attribute of <c:set> to request or above. The (default) page scope is exposed to current JSP only, not any included JSPs.
Note that the line
<c:set var="currentStudy" value='<%=(String)session.getAttribute("currentStudy")%>'/>
is unnecessary. The ${currentStudy} will already scan for variables in page, request, session and application scopes. As you've apparently already set it in the session scope, you don't need to copy it into the page scope. So, just remove that line. All with all, your top 2 <c:set> lines should be replaced with this single line:
<c:set var="hPediquestStudy" scope="request"><spring:message code="study.hpediquest.mapping" /></c:set>
and then it'll work the way you intended.
See also:
Our EL wiki page
I have a file with large content to display. For example in displaying user profile, every EL expression in <h:outputText/> needs an userId as an argument to bean which is taken from the session context. I declared this userId in xhtml file as
<ui:param name="userId" value="#{currentUser.id}"/>
I am passing this userId to bean methods as
<h:outputText value="#{profile.getAddress(userId)}"/>
<h:outputText value="#{profile.getContact(userId)}"/>
<s:link>
<f:param name="userId" value="#{userId}"/>
</s:link>
I am expectiong the session variable is invoked once for a page. But each time when the userId is processed the sessiion variable is called. Is this the correct behaviour? How to optimize this?
Yes this is the correct behavior. It would be interesting to see which is faster. I would guess it is faster to inject the currentUser in your profile component, and then to retrieve the correct object from there, instead of getting the address and contact by the userId each time. (Depends if you cache it in the component or not).
However, I would try to optimize it by injecting the currentUser in the profile component. That is the standard way of doing it.