Interesting EL expressions

OpenCms comes with several Java beans to provide access to OpenCms-specific functionality in JSPs. The variable cms is present in the page scope for each JSP. It makes an object of type org.opencms.jsp.util.CmsJspStandardContextBean available. The object provides a convenient way to access the most important OpenCms functions via JSTL/EL and gives access to several other Java beans shipped with OpenCms. A complete overview of the functionality exposed can be looked up in the JavaDoc.

In the following, the most important Java beans are described in more detail.

The standard context bean

Provider and availability

Provider class: org.opencms.jsp.util.CmsJspStandardContextBean
Access via: cms
Availability: In each JSP, initialized according to the current request.

Properties useful in a template

title: Get the title property of the currently requested page. Note, that the property has a special behavior for detail pages: Instead of using the title property of the displayed page, the title property of the resource providing the detail content is chosen.
isOnlineProject: Returns true if the request is performed in the “online” project. Otherwise returns false.
isEditMode: Returns true if edit mode is enabled. Otherwise returns false.

We exemplify the use of the properties in a template. The tasks are as follows:

Insert minimized javascript sources only in the online project, for debug reasons use the standard version otherwise
Set the page title of the web page according to the requested resource.
Place a special placeholder on top of the page if (and only if) in edit mode

The following code snippet fulfills the three tasks:

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<html>
 <head>
  <title><c:out value="${cms.title}"/></title>
  <meta charset="${cms.requestContext.encoding}">
  <!-- meta info etc. -->
  <cms:enable-ade/>
  <c:choice>
   <c:when test="${cms.isOnlineProject}">
    <cms:headincludes type="javascript" 
                      defaults="%(link.weak:/.../jquery-1.10.2.min.js)" />
   </c:when>
   <c:otherwise>
    <cms:headincludes type="javascript" 
                      defaults="%(link.weak:/.../jquery-1.10.2.js)" />
   </c:otherwise>
  </c:choice>
 </head>
 <body>
  <c:if test="${cms.isEditMode}">
   <!--=== Placeholder for OpenCms toolbar ===-->
   <div style="background: lightgray; height: 35px">&nbsp;</div>
  </c:if>
  <!-- Further code for creating the template -->
 </body>
</html>

Useful properties for localization

OpenCms supports a multi-language design for web pages. Thus, functionality and especially text output might be language specific. Which language to choose should be selected via a locale parameter. The standard context bean provides two choices for such locales:

locale: Returns the locale that is specific for the request context. The same locale is returned by cms.requestContext.locale.
workplaceLocale: Returns the locale configured in the workplace of the current user.

Here is a toy example:

<p>The locale of the request specific locale is "${cms.locale}".</p>

<p>The locale of your workplace is "${cms.workplaceLocale}".</p>

<p>To change the request specific locale, add the parameter "__locale=de" to the url.</p>

<p>The workplace locale is set via the preferences in your OpenCms workplace.</p>

Useful properties for formatting elements

It is sometimes useful to adjust formatters or function providers depending on the context. The standard context bean provides the following useful properties:

edited: Returns true if the element was re-rendered without reloading the whole page, e.g., after editing the element’s content or moving the element on the page. This state might lead to limited functionality of javascript. Therefore, you might display just a “please reload” message.
enableReload: Placing ${cms.enableReload} somewhere in your formatter will result in an automatically page reload when content is edited (or moved to a different container).
element: Returns the currently rendered element.
Return type: org.opencms.xml.containerpage.CmsContainerElementBean
container: Returns the container the currently rendered element is part of.
Return type: org.opencms.xml.containerpage.CmsContainerBean
detailContent: Returns the current detail content, or null if no detail content is requested.
Return type: org.opencms.file.CmsResource (see here)
detailPageAvailable: Returns true if a detail page is available for the current element.
detailRequest: Returns true if this is a request to a detail page.

Useful properties to access further interesting Java beans

Via the following properties, you obtain objects of the given beans, that are initialized according to the current request.

requestContext: Access to the request context bean org.opencms.file.CmsRequestContext.
vfs: Access to the VFS access bean org.opencms.jsp.util.CmsJspVfsAccessBean.

Note that here more properties that return objects of further Java beans are explained. In contrast to the properties listed above, these properties only make sense when formatting elements in container pages.

The request context bean

In OpenCms there is much more request specific information than in a usual stand-alone JSP. The request context bean provide access to such information. Do not confuse an object of such a bean with the implicitly present object requestScope that does not provide OpenCms specific information.

Provider and availability

Provider class: org.opencms.file.CmsRequestContext
Access via: cms.requestContext
Availabiliity: In each JSP, initialized according to the current request.

Properties of general interest

uri: Returns the OpenCms VFS URI of the requested resource.

Properties useful in a template

encoding: Returns the current content encoding to be used in HTTP response.

The encoding property should be used to define the charset as follows:

<meta charset="${cms.requestContext.encoding}">

Properties to access further interesting Java beans

currentUser: Access to the user bean org.opencms.file.CmsUser.
currentProject: Access to the project bean org.opencms.file.CmsProject.

The VFS access bean

The VFS access bean provides access to all resources in the OpenCms virtual file system. The bean is used to check if files exist, to read and set properties and permissions, to read XML documents, etc. In summary, you can access every resource in the VFS, read its metadata or access content. To enable such functionality, most properties of the bean return a lazy map that requires the URI of a resource as key to extract a value. If the current user has no access to the resource, or the resource does not exist, the return value will be empty.

When object.property returns a map, use object.property[key] to ask for the value of key key.

Provider and availability

Provider class: org.opencms.jsp.util.CmsJspVfsAccessBean
Access via: cms.vfs
Availability: In each JSP, initialized according to the current request.

Useful properties to explore resources in the VFS

exists: Returns true if a resource, whose URI is given as key, exists.
existsXML: Returns true if a resource, whose URI is given as key, exists and is an XML content or XML page.
property: Given an URI as key, a lazy map with property names as keys and their values as values is returned.
propertySearch: Like property, but the returned map also contains inherited values for properties.

The following example shows how to read the “NavText” property of a file and how to access a value in an XML content item.

<%@page taglibs="c" %>

<c:set var="uri" value="${cms.requestContext.uri}" />

<p> The "NavText" property value of the current URI (file
    ${cms.vfs.resource[uri].name}) is 
    "${cms.vfs.property[uri]['NavText']}".
</p>
<p> The Text value of a selected Jumbotron XML content is
    "${cms.vfs.xml['/demo/.content/jumbotrons/jt_00001.xml'].value.Text}".
</p>

Useful properties to access further Java beans

permissions: Access to the permission set bean org.opencms.security.CmsPermissionSet.
resource: Access to the resource bean org.opencms.file.CmsResource.
xml: Access to the content access bean org.opencms.jsp.util.CmsJspContentAccessBean.

The user bean

The user bean provides an interface to access manifold user information.

Provider and availability

Provider class: org.opencms.file.CmsUser
Access via: cms.requestContext.currentUser
Availability: In each JSP, initialized according to the current request.

Useful properties

guestUser: Returns true if the user is not logged in.
fullName: Returns “firstname lastname (username)”.
firstname: Returns the firstname of the user.
lastname: Returns the lastname of the user.
email: Returns the email of the user.
address: Returns the address of the user.
institution: Returns the institution information of the user.

In the following example JSP we check if a user is logged on. If so, we greet them by name.

<%@page taglibs="c" %>

<c:set var="user" value="${cms.requestContext.currentUser}" />

<c:choose>
  <c:when test="${user.guestUser}">
  	You are not logged in.
  </c:when>
  <c:otherwise>Hi ${user.fullName}!</c:otherwise>
</c:choose>

The project bean

The project bean provides access to project information. In OpenCms files can belong to different projects. There is just one “online” project, but several different projects that contain “offline” resources are possible. One such project, the “offline” project, is predefined.

Provider and availability

Provider class: org.opencms.file.CmsProject
Access via: cms.requestContext.currentProject
Availability: In each JSP, initialized according to the current request.

Useful properties

name: Returns the name of the project.
description: Returns the description of the project.
dateCreated: Returns the creation date of the project.
uuid: Returns the id of the project.

In the following example JSP, we output when the current project’s name and creation date.

<%@page taglibs="c" %>

<c:set var="project" value="${cms.requestContext.currentProject}" />

<p> 
Your are in the project "${project.name}" that was created on
${cms:convertDate(project.dateCreated)}.
</p>

The resource bean

Each entry in the OpenCms VFS can be considered as a resource. The resource bean allows accessing metadata of such resources, such as properties, attributes, version, name, etc.

Provider and availability

Provider class: org.opencms.file.CmsResource
Access via: cms.vfs.resource[<URI>]
Availability: Whenever the requested URI exists and the current user has the necessary permissions.

Useful properties

dateCreated: Returns the date of the creation of this resource.
dateReleased: Returns the release date of this resource.
dateExpired: Returns the expiration date of this resource.
dateLastModified: Returns the date of the last modification of this resource.
dateContent: Returns the date of the last modification of the content of this resource.
name: Returns the file name of this resource without parent folders, for example “index.html”.