I have some problem with the Google's AutoBean serialization and deserialization.
I have an AutoBean that contains primitive types and Maps as well. I can serialize and deserialize the primitive types without any problem, but when i try to read the deserialized Map, i get NullPointerException.
Have you ever met with a similar problem before? There is a JUnit test that representes my problem. The first two asserts are passes, but the third fails.
public class AutoBeanTest {
#Test
public void test() throws Exception {
MyFactory myFactory = AutoBeanFactorySource.create(MyFactory.class);
Options options = myFactory.options().as();
options.setMyInt(5);
HashMap<Double, Boolean> map = newHashMap();
map.put(8.0, true);
map.put(9.1, false);
options.setMyMap(map);
Options deserialized = AutoBeanCodex.decode(myFactory, Options.class, AutoBeanCodex.encode(AutoBeanUtils.getAutoBean(options)).getPayload()).as();
assertEquals(deserialized.getMyInt(),5);
assertTrue(options.getMyMap().containsKey(8d));
assertTrue(deserialized.getMyMap().containsKey(8d));
}
public interface MyFactory extends AutoBeanFactory {
AutoBean<Options> options();
}
public interface Options {
public int getMyInt();
void setMyInt(int myInt);
Map<Double, Boolean> getMyMap();
void setMyMap(Map<Double, Boolean> myMap);
}
}
I've been playing around with the AutoBean functionality a while ago. I think it is still kind a buggy. I'm quite sure the exceptions is caused by a bug in the AutoBean code, not in your code.
If you run the above sample code in a debugger and check the generated JSON, things look fine. You can even call deserialized.getMyMap().size() and get the correct value, but once you want to access the content errors occur.
There is a workaround, just use Map<String, String> instead of Double or Boolean and it works...
Ackchyually... Autobeans is doing it correctly as in JSON only strings are allowed as keys. But of course the error message should be more helpful.
Related
I have a service implemented with Dropwizard and I need to dump incorrect requests somewhere.
I saw that there is a possibility to customise the error message by registering ExceptionMapper<JerseyViolationException>. But I need to have the complete request (headers, body) and not only ConstraintViolations.
You can inject ContainerRequest into the ExceptionMapper. You need to inject it as a javax.inject.Provider though, so that you can lazily retrieve it. Otherwise you will run into scoping problems.
#Provider
public class Mapper implements ExceptionMapper<ConstraintViolationException> {
#Inject
private javax.inject.Provider<ContainerRequest> requestProvider;
#Override
public Response toResponse(ConstraintViolationException ex) {
ContainerRequest request = requestProvider.get();
}
}
(This also works with constructor argument injection instead of field injection.)
In the ContainerRequest, you can get headers with getHeaderString() or getHeaders(). If you want to get the body, you need to do a little hack because the entity stream is already read by Jersey by the time the mapper is reached. So we need to implement a ContainerRequestFilter to buffer the entity.
public class EntityBufferingFilter implements ContainerRequestFilter {
#Override
public void filter(ContainerRequestContext containerRequestContext) throws IOException {
ContainerRequest request = (ContainerRequest) containerRequestContext;
request.bufferEntity();
}
}
You might not want this filter to be called for all requests (for performance reasons), so you might want to use a DynamicFeature to register the filter just on methods that use bean validation (or use Name Binding).
Once you have this filter registered, you can read the body using ContainerRequest#readEntity(Class). You use this method just like you would on the client side with Response#readEntity(). So for the class, if you want to keep it generic, you can use String.class or InputStream.class and convert the InputStream to a String.
ContainerRequest request = requestProvider.get();
String body = request.readEntity(String.class);
I am using Spring 4 + Jackson 2 and have written a fully functional POST method using #RequestBody on a custom class. This method has no trouble unmarshalling the object.
#ResponseBody
#RequestMapping(value="store", method = RequestMethod.POST)
public ServiceResponse store(#RequestBody CustomClass list) {
...
}
// Request: { code: "A", amount: 200 }
When I attempted to add another method to handle a collection of the same class instead, my POST requests were returning with the following error.
HTTP Status 400: The request sent by the client was syntactically incorrect.
I note that this error typically occurs when the JSON submitted does not match the entity class. However, all I am doing is submitting an array of the same object instead of the object itself, which has already proven to work.
#ResponseBody
#RequestMapping(value="store-bulk", method = RequestMethod.POST)
public ServiceResponse storeBulk(#RequestBody List<CustomClass> list) {
...
}
// Request: [{ code: "A", amount: 200 }, { code: "B", amount: 400 }]
Am I missing something here?
In Java, type information for generics is erased at runtime, so Spring sees your List<CustomClass> object as List<Object> object, thus it cannot understand how to parse it.
One of ways to solve it, you could capture the type information by creating a wrapper class for your list, like this:
public class CustomClassList extends ArrayList<CustomClass> {
}
Sergey is right that the issue is due to type erasure. Your easiest way out is to bind to an array, so
#ResponseBody
#RequestMapping(value="store-bulk", method = RequestMethod.POST)
public ServiceResponse storeBulk(#RequestBody CustomClass[] object) {
...
}
The answer is that Spring 4 doesn't actually get rid of type erasure, contrary to what some other solutions suggest. While experimenting on debugging via manual unmarshalling, I decided to just handle that step myself instead of an implicit cast that I have no control over. I do hope someone comes along and proves me wrong, demonstrating a more intuitive solution though.
#ResponseBody
#RequestMapping(value="store-bulk", method = RequestMethod.POST)
public ServiceResponse storeBulk(#RequestBody String json) {
try {
List<CustomClass> list = new ObjectMapper().readValue(json, new TypeReference<List<CustomClass>>() { });
...
} catch (Exception e) {
...
}
}
Bonus: Right after I got this working, I bumped into this exception:
IllegalStateException: Already had POJO for id
If anyone gets this, it's because the objects in the list happen to reference some object that another item in the list already references. I could work around this since that object was identical for my entire collection, so I just removed the reference from the JSON side from all but the first object. I then added the missing references back after the JSON was unmarshalled into the List object.
Two-liner for the Java 8 users (the User object reference was the issue in my case):
User user = list.get(0).getUser();
list.stream().filter(c -> c.getUser() == null).forEach(t -> t.setUser(user));
When i try to insert a new entry to a deserialized Map instance i get no exception but the Map is not modified. This EntryPoint code probes it. I'm doing anything wrong?
public class Test2 implements EntryPoint {
public interface SomeProxy {
Map<String, List<Integer>> getStringKeyMap();
void setStringKeyMap(Map<String, List<Integer>> value);
}
public interface BeanFactory extends AutoBeanFactory {
BeanFactory INSTANCE = GWT.create(BeanFactory.class);
AutoBean<SomeProxy> someProxy();
}
#Override
public void onModuleLoad() {
SomeProxy proxy = BeanFactory.INSTANCE.someProxy().as();
proxy.setStringKeyMap(new HashMap<String, List<Integer>>());
proxy.getStringKeyMap().put("k1", new ArrayList<Integer>());
proxy.getStringKeyMap().put("k2", new ArrayList<Integer>());
String payload = AutoBeanCodex.encode(AutoBeanUtils.getAutoBean(proxy)).toString();
proxy = AutoBeanCodex.decode(BeanFactory.INSTANCE, SomeProxy.class, payload).as();
// insert a new entry into a deserialized map
proxy.getStringKeyMap().put("k3", new ArrayList<Integer>());
System.out.println(proxy.getStringKeyMap().keySet()); // the keySet is [k1, k2] :-( ¿where is k3?
}
}
Shouldn't AutoBeanCodex.encode(AutoBeanUtils.getAutoBean(proxy)).toString(); be getPayLoad()
I'll check the code later, and I don't know if that is causing the issue. But it did stand out as different from my typical approach.
Collection classes such as java.util.Set and java.util.List are tricky because they operate in terms of Object instances. To make collections serializable, you should specify the particular type of objects they are expected to contain through normal type parameters (for example, Map<Foo,Bar> rather than just Map). If you use raw collections or maps you will get bloated code and be vulnerable to denial of service attacks.
Font: http://www.gwtproject.org/doc/latest/DevGuideServerCommunication.html#DevGuideSerializableTypes
In my GWT application i'm trying to setup a DI mechanism wihich would allow me to have all the commonly necessary stuff at hand everywhere. I'm using google-gin which is an adaptation of guice for GWT. I have an injector interface defined as this:
#GinModules(InjectionClientModule.class)
public interface MyInjector extends Ginjector {
public PlaceController getPlaceController();
public Header getHeader();
public Footer getFooter();
public ContentPanel getContent();
public EventBus getEventBus();
public PlaceHistoryHandler getPlaceHistoryHandler();
}
My injection module is this:
public class InjectionClientModule extends AbstractGinModule {
public InjectionClientModule() {
super();
}
protected void configure() {
bind(Header.class).in(Singleton.class);
bind(Footer.class).in(Singleton.class);
bind(ContentPanel.class).in(Singleton.class);
bind(EventBus.class).to(SimpleEventBus.class).in(Singleton.class);
bind(PlaceController.class).toProvider(PlaceControllerProvider.class).asEagerSingleton();
bind(PlaceHistoryHandler.class).toProvider(PlaceHistoryHandlerProvider.class).asEagerSingleton();
}
}
When calling MyInjector injector = GWT.create(MyInjector.class); i'm gettign the following exception:
java.lang.NullPointerException: null
at com.google.gwt.inject.rebind.BindingsProcessor.createImplicitBinding(BindingsProcessor.java:498)
at com.google.gwt.inject.rebind.BindingsProcessor.createImplicitBindingForUnresolved(BindingsProcessor.java:290)
at com.google.gwt.inject.rebind.BindingsProcessor.createImplicitBindingsForUnresolved(BindingsProcessor.java:278)
at com.google.gwt.inject.rebind.BindingsProcessor.process(BindingsProcessor.java:240)
at com.google.gwt.inject.rebind.GinjectorGeneratorImpl.generate(GinjectorGeneratorImpl.java:76)
at com.google.gwt.inject.rebind.GinjectorGenerator.generate(GinjectorGenerator.java:47)
at com.google.gwt.core.ext.GeneratorExtWrapper.generate(GeneratorExtWrapper.java:48)
at com.google.gwt.core.ext.GeneratorExtWrapper.generateIncrementally(GeneratorExtWrapper.java:60)
at com.google.gwt.dev.javac.StandardGeneratorContext.runGeneratorIncrementally(StandardGeneratorContext.java:647)
at com.google.gwt.dev.cfg.RuleGenerateWith.realize(RuleGenerateWith.java:41)
at com.google.gwt.dev.shell.StandardRebindOracle$Rebinder.rebind(StandardRebindOracle.java:78)
at com.google.gwt.dev.shell.StandardRebindOracle.rebind(StandardRebindOracle.java:268)
at com.google.gwt.dev.shell.ShellModuleSpaceHost.rebind(ShellModuleSpaceHost.java:141)
at com.google.gwt.dev.shell.ModuleSpace.rebind(ModuleSpace.java:585)
at com.google.gwt.dev.shell.ModuleSpace.rebindAndCreate(ModuleSpace.java:455)
at com.google.gwt.dev.shell.GWTBridgeImpl.create(GWTBridgeImpl.java:49)
at com.google.gwt.core.client.GWT.create(GWT.java:97)
The problem is that the PlaceController class actually depends on one of the other dependencies. I've implemented it's provider like this:
public class PlaceControllerProvider implements Provider<PlaceController> {
private final PlaceController placeController;
#Inject
public PlaceControllerProvider(EventBus eventBus) {
this.placeController = new PlaceController(eventBus);
}
#Override
public PlaceController get() {
return placeController;
}
}
what should i change for this to work?
Old question but having the same problem I kept falling here. I finally found the way to know which class is messing during ginjection.
When I launch my app in development mode and put stack to Trace, I noticed there is a step called : "Validating newly compiled units".
Under this, I had an error but I didn't notice it since I had to expand 2 nodes which weren't even in red color.
The error was "No source code available for type com.xxx.xxxx ...", which was due to a bad import on client side which couldn't be converted to Javascript.
Hope this may help other here !
While I'm not actually seeing how the errors you're getting are related to the PlaceController being injected, I do see that the provider is returning a singleton PlaceController even if the provider were not bound as an eager singleton or in a different scope. The correct way to write that provider would be:
public class PlaceControllerProvider implements Provider<PlaceController> {
private final EventBus eventBus;
#Inject
public PlaceControllerProvider(EventBus eventBus) {
this.eventBus = eventBus;
}
#Override
public PlaceController get() {
return new PlaceController(eventBus);
}
}
Let guice handle the scoping i.e. "Letting guice work for you".
Other than that, I almost bet that your problem is due to the use of asEagerSingleton. I recommend you try this with just in(Singleton.class) and I further posit that you didn't really need the singleton to be eager. It seems others had problems with the behavior too, there's some indication that it has to do with overusing asEagerSingleton or misunderstanding the #Singleton annotation in a few cases.
I also got a lot of NullPointerException warnings using GIN 1.x with no real explanation of what happened. When I upgraded to gin 2.0 I was told with high accuracy what the error was. You might be helped by upgrading to the 2.0 version that was released a year after you asked this question.
Had the same problem problem, same trace, and the error was that I used "server" classes in my "client" classes, so GIN can't find these classes.
I mean by "server" and "client" the packages in my project.
Hope this could help
I am working in J2EE 5 using JPA, I have a working solution but I'm looking to clean up the structure.
I am using EntityListeners on some of the JPA objects I am persisting, the listeners are fairly generic but depend on the beans implementing an interface, this works great if you remember to add the interface.
I have not been able to determine a way to tie the EntityListener and the Interface together so that I would get an exception that lead in the right direction, or even better a compile time error.
#Entity
#EntityListener({CreateByListener.class})
public class Note implements CreatorInterface{
private String message;....
private String creator;
....
}
public interface CreatorInterface{
public void setCreator(String creator);
}
public class CreateByListener {
#PrePersist
public void dataPersist(CreatorInterface data){
SUser user = LoginModule.getUser();
data.setCreator(user.getName());
}
}
This functions exactly the way I want it to, except when a new class is created and it uses the CreateByListener but does not implement the CreatorInterface.
When this happens a class cast exception is thrown somewhere deep from within the JPA engine and only if I happen to remember this symptom can I figure out what went wrong.
I have not been able to figure a way to require the interface or test for the presence of the interface before the listener would be fired.
Any ideas would be appreciated.
#PrePersist
public void dataPersist(Object data){
if (!(data instanceof CreatorInterface)) {
throw new IllegalArgumentException("The class "
+ data.getClass()
+ " should implement CreatorInterface");
}
CreatorInterface creatorInterface = (CreatorInterface) data;
SUser user = LoginModule.getUser();
creatorInterface.setCreator(user.getName());
}
This does basically the same thing as what you're doing, but at least you'll have a more readable error message indicating what's wrong, instead of the ClassCastException.