How to parse JSON Response to POJO with AndroidAnnotations?

Question

I'm using AndroidAnnotations to build a Rest for an Android Application. On the Serverside im using PHP, which send a json looking like :

{"tag":"register","success":0,"error":2,"msg":"User already existed","body":[]}

I have two POJOS :

User.java:

public class User implements Serializable {
    private String name;
private String email;
private String password;

    //getter and setter Methods
}

Response.java:

public class RegistrationResponse implements Serializable {

private String tag;
private int success;
private int error;
private String msg;
private String body;

    //getter and setter Methods
}

Rest Client:

@Rest(rootUrl = "http://my.domain.com", converters = {
    MappingJacksonHttpMessageConverter.class,
    StringHttpMessageConverter.class, GsonHttpMessageConverter.class }, interceptors = { MyInterceptor.class })
public interface RestClient extends RestClientErrorHandling {
    @Post("/user/register/{name}/{email}/{pass}")
    @Accept(MediaType.APPLICATION_JSON_VALUE)
    Response sendUserRegistration(User user, String name, String email,
        String pass);

    RestTemplate getRestTemplate();
}

Activity.java:

//User and Response are POJOs
Response result = RestClient.sendUserRegistration(user,
                user.getName(),user.getEmail(),user.getPassword());

But i got an Null Pointer Exception error on Activity.java. But if i change the return value of "sendUserRegistration" function to String all work. So my "Response" POJO seems not to be converted from AndroidAnnotations.

How can i convert the Rest Response to my "Response"-POJO using AndroidAnnotations?

Answer 1

AA relies on Spring Android RestTemplate to make the rest call. And in order to build requests and handle responses this lib uses converters. And to know which converter the RestTemplate should use, it checks the content-type response header. As MappingJacksonHttpMessageConverter and GsonHttpMessageConverter handles only http response with content-type=application/json and your result is converted to string, I'm pretty sure you forgot to set this header in your php server. So it send the default one (ie: text/plain ) which is only handle by StringHttpMessageConverter .

Also, the body field is an object in your json example, but in your POJO you declared it as a String. So parsing will fail on this point.

Answer 2

You don't need to return the entire response object per rest call, just set the response to your custom object. Or you can also return a JsonObject also and use gson to convert it later on.

@Rest(rootUrl = "http://my.domain.com", converters = {
MappingJacksonHttpMessageConverter.class,
StringHttpMessageConverter.class, GsonHttpMessageConverter.class }, interceptors = {   MyInterceptor.class })
public interface RestClient extends RestClientErrorHandling {

    @Post("/user/register/{name}/{email}/{pass}")
    @Accept(MediaType.APPLICATION_JSON_VALUE)
    User sendUserRegistration(User user, String name, String email,
    String pass);

    RestTemplate getRestTemplate();
}

then just simply call

User newUser = RestClient.sendUserRegistration(user,
                user.getName(),user.getEmail(),user.getPassword());