Playing with Sling Post Servlet

In this post, we are going to create a Sling Post servlet which is invoked by an HTTP POST call. We will make an AJAX call to achieve this.

Since this a POST request, we will be using SlingAllMethodsServlet as a parent to our custom servlet.

Sling Post Servlet Example

in this example, we will make an HTTP post request via AJAX to add a node at a path in the JCR. After adding the node, we will also modify the node by adding a name property.

• Create an AEM Multimodule project in eclipse.
• Create a class SampleSlingPostServlet and paste the following code in it.

package org.redquark.demo.core.servlets;

import javax.jcr.Node;

import javax.jcr.RepositoryException;

import javax.servlet.Servlet;

import org.apache.sling.api.SlingHttpServletRequest;

import org.apache.sling.api.SlingHttpServletResponse;

import org.apache.sling.api.resource.PersistenceException;

import org.apache.sling.api.resource.Resource;

import org.apache.sling.api.resource.ResourceResolver;

import org.apache.sling.api.servlets.HttpConstants;

import org.apache.sling.api.servlets.SlingAllMethodsServlet;

import org.osgi.framework.Constants;

import org.osgi.service.component.annotations.Component;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

/**

 * @author Anirudh Sharma

 *

 * This class shows the usage of SlingPostServlet

 */

@Component(service = Servlet.class, property = {

 Constants.SERVICE_DESCRIPTION + "=Simple Demo Servlet",

 "sling.servlet.methods=" + HttpConstants.METHOD_POST,

 "sling.servlet.paths=" + "/bin/submitdata"

})

public class SampleSlingPostServlet extends SlingAllMethodsServlet {

 /**

  * Generated serialVersionUID

  */

 private static final long serialVersionUID = -159625176093879129 L;

 /**

  * Logger

  */

 private static final Logger log = LoggerFactory.getLogger(SampleSlingPostServlet.class);

 /**

  * Overridden doPost() method which is invoked when an HTTP post request is made

  */

 @Override

 protected void doPost(SlingHttpServletRequest request, SlingHttpServletResponse response) {

  try {

   /**

    * Getting the instance of resource resolver from the request

    */

   ResourceResolver resourceResolver = request.getResourceResolver();

   /**

    * Getting the resource object via path

    */

   Resource resource = resourceResolver.getResource("/content/demoproject/en");

   log.info("Resource is at path {}", resource.getPath());

   /**

    * Adapt the resource to javax.jcr.Node type

    */

   Node node = resource.adaptTo(Node.class);

   /**

    * Create a new node with name and primary type and add it below the path specified by the resource

    */

   Node newNode = node.addNode("demoNode", "nt:unstructured");

   /**

    * Setting a name property for this node

    */

   newNode.setProperty("name", "Demo Node");

   /**

    * Commit the changes to JCR

    */

   resourceResolver.commit();

  } catch (RepositoryException e) {

   log.error(e.getMessage(), e);

   e.printStackTrace();

  } catch (PersistenceException e) {

   log.error(e.getMessage(), e);

   e.printStackTrace();

  }

 }

}

• Here we are registering the servlet via path /bin/submitdata. Property sling.servlet.methods define the HTTP method to be used i.e. POST in this case. Since we are writing the data, we have extended the class from SlingAllMethodsServlet. 
• The logic in the doPost() creates a node under a given path and added a name property in it.
• Now to call this servlet via AJAX, create a new cq:component and in the HTML file of the component, add below code

AJAX call

for SampleSlingPostServlet

 <

 script >

 $.ajax({

  type: "POST",

  url: '/bin/submitdata',

  /*data : {         

  pass your request parameter here, currently we are not passing any data     

  },*/

  success: function(data, textStatus, jqXHR) {

   //write your logic that you need to perform on sucess                           

  },

  error: function(XMLHttpRequest, textStatus, errorThrown) {

   //write your logic that you need to perform on error     

  }

 }); <

/script>

• Note that the url property has the same path by which the servlet is registered.
• When we drag and drop the component on an AEM page, the post servlet will invoke and a node with name property will be created. You can check the same in CRXDE.

CRXDE

Conclusion

Congratulations!! 🙋 we have created a sling post servlet and invoked it via an AJAX call. I hope you enjoyed this post.