[WSO2 ESB] Change the response payload using class mediator

Wso2 ESB allows you to change the backend response payload as the way you want. You can achive this by writing a class mediator as mentioned below.

Let’s assume your back end has responded with some JSON payload as follows,

{
     "name": "Identifier",
     "type": "string",
     "size": 255
}

Now you need to change this to the following error message,

   <jsonObject>
          <status>403</status>
          <errorMessage>
               <error>Authoraization Missing</error>
                <detail>Authoraization Credentials invalid</detail>
                <title>Authoraization Error</title>
          </errorMessage>
  </jsonObject>

You can achieve this by writing a class mediator as follows,

import org.apache.synapse.MessageContext;
import org.apache.synapse.mediators.AbstractMediator;
import org.apache.synapse.core.axis2.Axis2MessageContext;

import org.apache.synapse.commons.json.JsonUtil;
import org.json.JSONObject;


public class addSignature extends AbstractMediator {

  @Override
  public boolean mediate(MessageContext messageContext) {

    try {

    org.apache.axis2.context.MessageContext axis2MessageContext = ((Axis2MessageContext)messageContext).getAxis2MessageContext();

    JSONObject jsonBody = new JSONObject();
    JSONObject jsonError = new JSONObject();
    jsonError.put("error","Authoraization Missing");
    jsonError.put("detail","Authoraization Credentials invalid");
    jsonError.put("title","Authoraization Error");

    jsonBody.put("status", "403");
    jsonBody.put("errorMessage", jsonError);

    String transformedJson = jsonBody.toString();

   JsonUtil.newJsonPayload(axis2MessageContext,transformedJson,  true, true);
// change the response type to XML
  axis2MessageContext.setProperty("messageType", "application/xml");
  axis2MessageContext.setProperty("ContentType", "application/xml");

    } catch (Exception e) {
         System.err.println("Error: " + e);
         return false;
    }
 return true;
 }

}