Q:

smartgwt listgrid RestDataSource not populating

Im new using this front end framework application...
I recently started to work with smartgwt and i'm bulding a new application with a Spring MVC integration.  
I'm using a ListGrid with a RestDataSource (Consume the Rest service with mvc:annotation-driven for plain JSON)
I can see that the servaice gets consuming properly perhaps my grid is never shown with the data in it.  
Can someone help me here ? 
Here's my ListGrid class 
public class ListGrid extends com.smartgwt.client.widgets.grid. ListGrid {
private final SpringJSONDataSource springJSONDataSource;

public ListGrid(List<DataSourceField> fields) {
    this(new PatientDataSource(fields));
}

public ListGrid(SpringJSONDataSource springJSONDataSource) {
    this.springJSONDataSource = springJSONDataSource;
    init();
}

private void init() {
    setAutoFetchData(true);
    setAlternateRecordStyles(true);
    setEmptyCellValue("???"); 
    setDataPageSize(50);

    setDataSource(springJSONDataSource);
}

}
Now there's the DataSource implmentation 
public abstract class SpringJSONDataSource extends RestDataSource {
protected final HTTPMethod httpMethod;

public SpringJSONDataSource(List<DataSourceField> fields) {
    this(fields, HTTPMethod. POST);
}

public SpringJSONDataSource(List<DataSourceField> fields, HTTPMethod httpMethod) {
    this.httpMethod = httpMethod;
    setDataFormat(DSDataFormat. JSON);
    addDataSourceFields(fields);
    setOperationBindings(getFetch());
    addURLs();
}

private void addURLs() {
    if(getUpdateDataURL() ! = null)
        setUpdateDataURL(getUpdateDataURL());

    if(getRemoveDataURL() ! = null)
        setRemoveDataURL(getRemoveDataURL());

    if(getAddDataURL() ! = null)
        setAddDataURL(getAddDataURL());

    if(getFetchDataURL() ! = null)
        setFetchDataURL(getFetchDataURL());

}

private void addDataSourceFields(List<DataSourceField> fields) {
    for (DataSourceField dataSourceField : fields) {
        addField(dataSourceField);
    }
}

protected abstract OperationBinding getFetch();
protected abstract OperationBinding getRemove();
protected abstract OperationBinding getAdd();
protected abstract OperationBinding getUpdate();

public abstract String getUpdateDataURL();
public abstract String getRemoveDataURL();
public abstract String getAddDataURL();
public abstract String getFetchDataURL();

}
The class PatientDataSource that extends SpringJSONDataSource
public class PatientDataSource extends SpringJSONDataSource {
public PatientDataSource(List<DataSourceField> fields) {
    super(fields);
    setPrettyPrintJSON(true);
}

@Override
protected OperationBinding getFetch() {
    OperationBinding fetch = new OperationBinding();
    fetch.setOperationType(DSOperationType. FETCH);
    fetch.setDataProtocol(DSProtocol. POSTMESSAGE);
    DSRequest fetchProps = new DSRequest();
    fetchProps.setHttpMethod(httpMethod.toString());
    fetch.setRequestProperties(fetchProps);

    return fetch;
}

@Override
public String getFetchDataURL() {

    return "/spring/fetchPatients";
}

@Override
protected OperationBinding getRemove() {
    return null;
}

@Override
public String getRemoveDataURL() {
    return null;
}

@Override
protected OperationBinding getAdd() {
    return null;
}

@Override
public String getAddDataURL() {
    return null;
}

@Override
protected OperationBinding getUpdate() {
    return null;
}

@Override
public String getUpdateDataURL() {
    return null;
}

}
My spring controller PatientControler
@Controller
public class PatienController {
Logger logger = Logger.getLogger(PatienController.class);

@Autowired
private PatientServices patientServices;

@RequestMapping(value = "/patientTest", method = RequestMethod. GET)
@ResponseBody
public Object getTest()
{
    return patientServices.getAllPatients();
}

@RequestMapping(value = "/fetchPatients", method = RequestMethod. POST)
@ResponseBody
public Object getAllPatients()
{
    return patientServices.getAllPatients();
}

}
PatientServiceImpl
public class PatientServicesImpl implements PatientServices {
public List<Patient> getAllPatients() {

    List<Patient> patients = new ArrayList<Patient>();
    Patient patient;

    for(int i = 0 ; i < 500 ; i++){
        patient = new Patient();
        patient.setDateOfBirth(new Date());
        patient.setFirstName("Joe");
        patient.setMiddleName("Moe");
        patient.setLastName("Blow");
        patient.setLastConsultation(new Date());
        patient.setSex(Sex. M);

        patients.add(patient);
    }

    return patients;
}

}
*Im Really stuck right now i've been looking for all type of answers .... but so far nothing worked when i tried to override the transformResponse from my RestDataSource impentation the parameter "data" as an OBJECT, returns me an array [object Object],[object Object],[object Object],[object Object],[object Object] *

A:

The Data which is transferred from the RestDataSource has a specific format which is described in the JavaDoc of the RestDataSource
Your server must understand the request and send back a valid response. 
At the moment your example doesn't seem to honour the contract. 
To debug the traffic send to and from your server you can use the SmartClient-Console.  You can open it by a browser bookmark like this:
javascript:isc.showConsole()

Of cause you need to deploy this console by adding the following module to your gwt.xml
<inherits name="com.smartclient.tools. SmartClientTools"/>

Now go to the RPC Tab and check Track-RPCs

