Generating Portlet URLs

Developing Your First Portlet

Step 3 of 8

Recall that users can place multiple portlets on a single page. As a developer, you have no idea what other portlets may share a page with yours. This means that you can’t define URLs for various functions in your application like you otherwise would.

For example, consider a Calendar application that a user puts on the same page as a Blog application. To implement the functionality for deleting calendar events and blog entries in the respective application, both application developers append the del parameter to the URL and give it a primary key value so the application can look up and delete the calendar event or blog entry. Since both applications read this parameter, their delete functionality clashes.

System-generated URLs prevent this. If the system generates a unique URL for each piece of functionality, multiple applications can coexist in perfect harmony.

In view.jsp, follow these steps to create system-generated URLs in your portlet:

  1. Add these tags below <%@ include file="/init.jsp" %>, but above the <aui:button-row> tag:

    <portlet:renderURL var="addEntryURL">
        <portlet:param name="mvcPath" value="/edit_entry.jsp"></portlet:param>
    </portlet:renderURL>
    
  2. Add this attribute to the <aui:button> tag, before value="Add Entry":

    onClick="<%= addEntryURL.toString() %>"
    

    Your view.jsp page should now look like this:

    <%@ include file="/init.jsp" %>
    
    <portlet:renderURL var="addEntryURL">
        <portlet:param name="mvcPath" value="/edit_entry.jsp"></portlet:param>
    </portlet:renderURL>
    
    <aui:button-row>
        <aui:button onClick="<%= addEntryURL.toString() %>" value="Add Entry"></aui:button>
    </aui:button-row>
    

The <portlet:renderURL> tag’s var attribute creates the addEntryURL variable to hold the system-generated URL. The <portlet:param> tag defines a URL parameter to append to the URL. In this example, a URL parameter named mvcPath with a value of /edit_entry.jsp is appended to the URL.

Note that your GuestbookPortlet class (located in your guestbook-web module’s com.liferay.docs.guestbook.portlet package) extends Liferay’s MVCPortlet class. In a Liferay MVC portlet, the mvcPath URL parameter indicates a page within your portlet. To navigate to another page in your portlet, use a portal URL with the parameter mvcPath to link to the specific page.

In the example above, you created a renderURL that points to your application’s edit_entry.jsp page, which you haven’t yet created. Note that using an AlloyUI button to follow the generated URL isn’t required. You can use any HTML construct that contains a link. Users can click your button to access your application’s edit_entry.jsp page. This currently produces an error since no edit_entry.jsp exists yet. Creating edit_entry.jsp is your next step.

« Creating an Add Entry ButtonLinking to Another Page »
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