SmartGWT RestDataSource calling an existing REST service - json

Question

I have a database back-end that I've thoroughly tested with several unit tests. The controller looks like this:
#RequestMapping(value = "/create", method = RequestMethod.POST, produces = "application/json", headers = "content-type=application/json")
public #ResponseBody UserDTO createUser(#RequestBody UserDTO user)
{
UserEntity userEntity = service.add(user);
return mappingUser(userEntity);
}
The unit test looks like:
#Test
public void testCreateUser() throws Exception
{
UserDTO userDto = createUserDto();
String url = BASE_URL + "/rest/users/create";
UserDTO newUserDto = restTemplate
.postForObject(url, userDto, UserDTO.class, new Object[]{});
}
I have confirmed that the unit test works great, and the actual web-service is called correctly, and data is put into the database.
Now, I am using a SmartGWT RestDataSource, and I am trying to configure the RestDataSource correctly to pass a new user in the request body, and return the new object. I want to send the data as JSON in the body, and return JSON from this call. So, it might be that I need to change the controller itself to match up with the datasource.
Here is the AbstractDataSource which extends RestDataSource:
import java.util.Map;
import com.google.gwt.http.client.URL;
import com.smartgwt.client.data.DSRequest;
import com.smartgwt.client.data.OperationBinding;
import com.smartgwt.client.data.Record;
import com.smartgwt.client.data.RestDataSource;
import com.smartgwt.client.types.DSOperationType;
import com.smartgwt.client.types.DSProtocol;
public abstract class AbstractRestDataSource extends RestDataSource
{
public AbstractRestDataSource(String id)
{
setID(id);
setClientOnly(false);
// set up FETCH to use GET requests
OperationBinding fetch = new OperationBinding();
fetch.setOperationType(DSOperationType.FETCH);
fetch.setDataProtocol(DSProtocol.GETPARAMS);
DSRequest fetchProps = new DSRequest();
fetchProps.setHttpMethod("GET");
fetch.setRequestProperties(fetchProps);
// set up ADD to use POST requests
OperationBinding add = new OperationBinding();
add.setOperationType(DSOperationType.ADD);
add.setDataProtocol(DSProtocol.POSTMESSAGE);
DSRequest addProps = new DSRequest();
addProps.setHttpMethod("POST");
addProps.setContentType("application/json");
add.setRequestProperties(addProps);
// set up UPDATE to use PUT
OperationBinding update = new OperationBinding();
update.setOperationType(DSOperationType.UPDATE);
update.setDataProtocol(DSProtocol.POSTMESSAGE);
DSRequest updateProps = new DSRequest();
updateProps.setHttpMethod("PUT");
update.setRequestProperties(updateProps);
// set up REMOVE to use DELETE
OperationBinding remove = new OperationBinding();
remove.setOperationType(DSOperationType.REMOVE);
DSRequest removeProps = new DSRequest();
removeProps.setHttpMethod("DELETE");
remove.setRequestProperties(removeProps);
// apply all the operational bindings
setOperationBindings(fetch, add, update, remove);
init();
}
#Override
protected Object transformRequest(DSRequest request)
{
super.transformRequest(request);
// now post process the request for our own means
postProcessTransform(request);
return request.getData();
}
/*
* Implementers can override this method to create a
* different override.
*/
#SuppressWarnings("rawtypes")
protected void postProcessTransform(DSRequest request)
{
StringBuilder url = new StringBuilder(getServiceRoot());
Map dataMap = request.getAttributeAsMap("data");
if (request.getOperationType() == DSOperationType.REMOVE)
{
// in case of remove, append the primary key
url.append(getPrimaryKeyProperty()).append("/").append(dataMap.get(getPrimaryKeyProperty()));
}
else if (request.getOperationType() == DSOperationType.UPDATE)
{
url.append("update");
appendParameters(url, request);
}
else if (request.getOperationType() == DSOperationType.FETCH && dataMap.size() > 0)
{
url.append(getPrimaryKeyProperty()).append("/").append(dataMap.get(getPrimaryKeyProperty()));
}
else if (request.getOperationType() == DSOperationType.ADD)
{
url.append("create");
}
System.out.println("AbstractRestDataSource: postProcessTransform: url=" + url.toString());
request.setActionURL(URL.encode(url.toString()));
}
/*
* This simply appends parameters that have changed to the URL
* so that PUT requests go through successfully. This is usually
* necessary because when smart GWT updates a row using a form,
* it sends the data as form parameters. Most servers cannot
* understand this and will simply disregard the form data
* sent to the server via PUT. So we need to transform the form
* data into URL parameters.
*/
#SuppressWarnings("rawtypes")
protected void appendParameters(StringBuilder url, DSRequest request)
{
Map dataMap = request.getAttributeAsMap("data");
Record oldValues = request.getOldValues();
boolean paramsAppended = false;
if (!dataMap.isEmpty())
{
url.append("?");
}
for (Object keyObj : dataMap.keySet())
{
String key = (String) keyObj;
if (!dataMap.get(key).equals(oldValues.getAttribute(key)) || isPrimaryKey(key))
{
// only append those values that changed or are primary keys
url.append(key).append('=').append(dataMap.get(key)).append('&');
paramsAppended = true;
}
}
if (paramsAppended)
{
// delete the last '&'
url.deleteCharAt(url.length() - 1);
}
}
private boolean isPrimaryKey(String property)
{
return getPrimaryKeyProperty().equals(property);
}
/*
* The implementer can override this to change the name of the
* primary key property.
*/
protected String getPrimaryKeyProperty()
{
return "id";
}
protected abstract String getServiceRoot();
protected abstract void init();
}
And here is the UserDataSource which extends AbstractRestDataSource:
import java.util.Map;
import com.google.gwt.http.client.URL;
import com.opensource.restful.shared.Constants;
import com.smartgwt.client.data.DSRequest;
import com.smartgwt.client.data.fields.DataSourceBooleanField;
import com.smartgwt.client.data.fields.DataSourceDateField;
import com.smartgwt.client.data.fields.DataSourceIntegerField;
import com.smartgwt.client.data.fields.DataSourceTextField;
import com.smartgwt.client.types.DSDataFormat;
import com.smartgwt.client.types.DSOperationType;
public class UserDataSource extends AbstractRestDataSource
{
private static UserDataSource instance = null;
public static UserDataSource getInstance()
{
if (instance == null)
{
instance = new UserDataSource("restUserDS");
}
return instance;
}
private UserDataSource(String id)
{
super(id);
}
private DataSourceIntegerField userIdField;
private DataSourceBooleanField userActiveField;
private DataSourceTextField usernameField;
private DataSourceTextField passwordField;
private DataSourceTextField firstnameField;
private DataSourceTextField lastnameField;
private DataSourceTextField emailField;
private DataSourceTextField securityQuestion1Field;
private DataSourceTextField securityAnswer1Field;
private DataSourceTextField securityQuestion2Field;
private DataSourceTextField securityAnswer2Field;
private DataSourceDateField birthdateField;
private DataSourceIntegerField positionIdField;
protected void init()
{
setDataFormat(DSDataFormat.JSON);
setJsonRecordXPath("/");
// set the values for the datasource
userIdField = new DataSourceIntegerField(Constants.USER_ID, Constants.TITLE_USER_ID);
userIdField.setPrimaryKey(true);
userIdField.setCanEdit(false);
userActiveField = new DataSourceBooleanField(Constants.USER_ACTIVE, Constants.TITLE_USER_ACTIVE);
usernameField = new DataSourceTextField(Constants.USER_USERNAME, Constants.TITLE_USER_USERNAME);
passwordField = new DataSourceTextField(Constants.USER_PASSWORD, Constants.TITLE_USER_PASSWORD);
firstnameField = new DataSourceTextField(Constants.USER_FIRST_NAME, Constants.TITLE_USER_FIRST_NAME);
lastnameField = new DataSourceTextField(Constants.USER_LAST_NAME, Constants.TITLE_USER_LAST_NAME);
emailField = new DataSourceTextField(Constants.USER_EMAIL, Constants.TITLE_USER_EMAIL);
securityQuestion1Field =
new DataSourceTextField(Constants.USER_SECURITY_QUESTION_1, Constants.TITLE_USER_SECURITY_QUESTION_1);
securityAnswer1Field =
new DataSourceTextField(Constants.USER_SECURITY_ANSWER_1, Constants.TITLE_USER_SECURITY_ANSWER_1);
securityQuestion2Field =
new DataSourceTextField(Constants.USER_SECURITY_QUESTION_2, Constants.TITLE_USER_SECURITY_QUESTION_2);
securityAnswer2Field =
new DataSourceTextField(Constants.USER_SECURITY_ANSWER_2, Constants.TITLE_USER_SECURITY_ANSWER_2);
birthdateField = new DataSourceDateField(Constants.USER_BIRTHDATE, Constants.TITLE_USER_BIRTHDATE);
positionIdField = new DataSourceIntegerField(Constants.USER_POSITION_ID, Constants.TITLE_USER_POSITION_ID);
// positionActiveField = new DataSourceBooleanField(Constants.USER_ACTIVE, Constants.TITLE_USER_ACTIVE);
// positionCodeField;
// positionDescriptionField;
setFields(userIdField, userActiveField, usernameField, passwordField, firstnameField, lastnameField,
emailField, birthdateField, securityQuestion1Field, securityAnswer1Field, securityQuestion2Field,
securityAnswer2Field, positionIdField);
}
protected String getServiceRoot()
{
return "rest/users/";
}
protected String getPrimaryKeyProperty()
{
return "userId";
}
/*
* Implementers can override this method to create a
* different override.
*/
#SuppressWarnings("rawtypes")
protected void postProcessTransform(DSRequest request)
{
// request.setContentType("application/json");
StringBuilder url = new StringBuilder(getServiceRoot());
Map dataMap = request.getAttributeAsMap("data");
if (request.getOperationType() == DSOperationType.REMOVE)
{
// in case of remove, append the primary key
url.append(getPrimaryKeyProperty()).append("/").append(dataMap.get(getPrimaryKeyProperty()));
}
else if (request.getOperationType() == DSOperationType.UPDATE)
{
url.append("update");
System.out.println("UserDataSource: postProcessTransform: update: url=" + url.toString());
}
else if (request.getOperationType() == DSOperationType.FETCH && dataMap.size() > 0)
{
url.append(getPrimaryKeyProperty()).append("/").append(dataMap.get(getPrimaryKeyProperty()));
}
else if (request.getOperationType() == DSOperationType.ADD)
{
url.append("create");
}
System.out.println("UserDataSource: postProcessTransform: url=" + url.toString());
request.setActionURL(URL.encode(url.toString()));
}
}
If I can find out how to get the UserDTO as JSON into the requestBody, I think I will have solved all my issues. For extra information you should know, I am using Spring 3.2 and the Jackson Message Converters configured in the springmvc-servlet.xml file.
At one point I did see all the data getting appended to the URL, but I would prefer if the data was not in the URL as parameters, but rather in the request body. SO, I need to know if this is possible, and how to do it.
Thanks for any help!!!

Answer 1

You probably want to undo all of these modifications and just implement the default RestDataSource protocol, which already passes the request body as JSON if you just call RestDataSource.setDataFormat(). There are sample JSON messages in the docs:
http://www.smartclient.com/smartgwtee/javadoc/com/smartgwt/client/data/RestDataSource.html
Among other problems you've created:
the different CRUD operations now go to distinct URLs and use different HTTP verbs, so they can no longer be combined into a single queue and sent together. This means you can't do basic things like perform a mixture of create and update operations together in a transaction, save a new Order along with it's OrderItems, or save data and also fetch dependent data needed to transition to a new screen.
you're assuming the "fetch" will be based on HTTP GET, but this requires awkward encoding of nested criteria structures (AdvancedCriteria) into URL parameters, which can easily hit the maximum URL length
For these and other reasons, most generated Java services do not meet the needs of a modern UI, and the auto-generation approach should not be used. Deeper explanation in the FAQ:
http://forums.smartclient.com/showthread.php?t=8159#aExistingRest