Result is null with JSON and Struts2

Question

I have created a simple form in Extjs4.1.

I am sending the request to Struts2 framework, and using the Strtus2JSON plugin, i have to recieve the response. But unfortunately, the response is null.

Action class

public String execute()throws Exception{
    Employee emp = new Employee();
    emp.setAddress(getAddress());
    emp.setDepartment(getDepartment());
    emp.setName(getName());
    emp.setSalary(getSalary());
    AddEmployeeService empService = new AddEmployeeService();
    boolean flag = empService.addEmployee(emp);
    resultJSONobj = new JSONObject();
    if(flag == true)
        resultJSONobj.put("success","Inserted Successfully");
    else
        resultJSONobj.put("failure","An error occured");
    System.out.println(resultJSONobj);
    return SUCCESS;

}

struts.xml

<struts>
    <package name="default" extends="struts-default, json-default">
        <action name="AddEmp" class = "actions.AddEmpAction">
            <result name = "success" type="json">
                <param name ="root">resultJSONobj</param>
            </result>      
        </action>
    </package>        
</struts>

Can anybody tell why iam getting the response as null ?

Andrea Ligios · Answer 1 · 2012-12-18T09:30:01.163

Do you have a Getter for resultJSONobj like this?:

public JSONObject getResultJSONobj(){ 
   return this.resultJSONobj; 
}

Add a namespace to your package, like this:

<package name="default" namespace="/" extends="struts-default, json-default">

And see if something has changed...

EDIT

As described in the guide,

'transient' fields are not serialized

fields without getter method are not serialized

Try like this:

Use a Map instead of your JSONObject. Not every class is accepted, and I'm not sure your JSONObject is serializable (do you implement serializable? do you declare a serialVersionUID? etc)

private Map resultJSONobj = new HashMap(); //instantiated at class level

// accessors
public Map getResultJSONobj() {
    return resultJSONobj;
}
public void setResultJSONobj(Map resultJSONobj) {
    this.resultJSONobj = resultJSONobj;
}

//...

public String execute()throws Exception{
    Employee emp = new Employee();
    emp.setAddress(getAddress());
    emp.setDepartment(getDepartment());
    emp.setName(getName());
    emp.setSalary(getSalary());
    AddEmployeeService empService = new AddEmployeeService();
    boolean flag = empService.addEmployee(emp);

    if(flag == true)
        resultJSONobj.put("success","Inserted Successfully");
    else
        resultJSONobj.put("failure","An error occured");
    System.out.println(resultJSONobj);
    return SUCCESS;

}

And change struts config like this:

<struts>
    <package name="default" extends="struts-default, json-default">

        <action name="AddEmp" class = "actions.AddEmpAction">
            <result name="success" type="json" />
        </action>
    </package>  

</struts>

Success is not necessary, but leave it for a clearer code, you can always remove it later.

Now, you should see this as result (if you doesn't have any other getter):

{  
   "resultJSONobj": {
       "success":"Inserted Successfully"
   }
}

or

{  
   "resultJSONobj": {
       "failure":"An error occured"
   }
}

I have added the getters and setters for the JSONObject. But now it was showing result as "{}", even though i have added a value in the JSONObject. — Srinivas B, Dec 18 '12 at 04:06

score 1 · Answer 2 · answered Jun 06 '13 at 08:40

in your configuration file struts.xml, please use

<param name="includeProperties">resultJSONobj.*</param>

Instead of

<param name="includeProperties">resultJSONobj</param>

I was facing the same issue before in my project, after I made the above change it works.

DarkHorse · Answer 3 · 2012-12-18T06:23:20.357

There are few things missing in your struts.xml file. After result is success, where are you going? Create json object instance outside your execute method and inside action class. Struts2JSON plugin serializes all action variables inside an action class. It might be that since you have only declared JSONobject in action class and actually creating it inside execute, JSON might be getting it {}.

Put

private JSONObject resultJSONobj = new JSONObject();

inside action class and outside execute and see, it might work. For more information you can go here http://struts.apache.org/2.2.3/docs/json-plugin.html

Result is null with JSON and Struts2

3 Answers3