Debugging JSF ManagedProperty NullPointer - jsf-2

Using JSF 2 on JBoss AS 7
Getting the following error:
07:36:39,579 SEVERE [javax.enterprise.resource.webcontainer.jsf.application] (http-/172.20.91.126:12580-16)
Error Rendering View[/views/afgarendesok.xhtml]:
com.sun.faces.mgbean.ManagedBeanCreationException:
Unable to set property searchManager for managed bean afgArendeBacking
at com.sun.faces.mgbean.ManagedBeanBuilder$BakedBeanProperty.set(ManagedBeanBuilder.java:615)
The searchManager property is defined in the AfgArendeBacking class as:
#ManagedProperty(value="#{afgArendeSokManager}")
private AfgArendeSokManager searchManager;
#Override
public AfgArendeSokManager getSearchManager() {
return searchManager;
}
public void setSearchManager(AfgArendeSokManager searchManager) {
this.searchManager = searchManager;
}
The AfgArendeSokManager is a #ManagedBean that is #SessionScoped.
Two things I don't get. One is why the error shuts down all usage of JSF not just for the session producing the error. The error seems to appear after non-usage both below the default session timeout and beyond. The other odd this is that a null pointer exception at line 606 in the BakedBeanProperty has to be the one the writeMethod variable. That variable is created via the PropertyDescriptor.getWriteMethod() call. This should have bombed earlier when creating baked bean (i.e. bakeBeanProperty method).
Any ideas how to debug? The property "searchManager" is resolved correctly since we can use the JSF views normally (both the getter/setter exist).
The search manager is our session scratch pad for propagating stuff between view and request scoped backing beans.

The article explains the issue of using reflection to access methods with covariant return types (see here: https://dzone.com/articles/covariant-return-type-abyssal). The article relates to Java 6 but the background information is very useful.
The issue you're facing and that hit us just this week (using Java 1.7.0_40) is not one of EL but of the java.beans.Introspector.

Related

IllegalStateException in conditional observer in Vaadin #RouteScoped component

We are using Vaadin 23 (23.0.9) with vaadin-cdi (14.0.0) and are having problems with conditional observers in #RouteScoped components (like it is described in the tutorial):
#RouteScoped
public class ScopedComponent extends Div {
private void onMessage(
#Observes(notifyObserver = IF_EXISTS)
MessageEvent message) {
setText(message.getText());
}
}
We are running on Tomcat 9 and use Weld (3.1.9.Final) as our CDI implementation.
Our current problem is that we get the following exception when firing an event that is observed in a #RouteScoped component:
java.lang.IllegalStateException: Route owner 'class XXX' instance is not available in the active navigation components chain: the scope defined by the bean 'YYY' doesn't exist.
We believe that the problem are the changes implemented in Vaadin CDI 13.0.0 (https://github.com/vaadin/cdi/releases/tag/13.0.0):
Trying to use #RouteScope when there is no active route component present is not allowed.
In the Weld implementation we are using, the method getReceiverIfExists calls the method getContextualStorage() in class RouteScopedContext. And getReceiverIfExists is called before the reception of the observer is considered. Therefore all classes that have an observer on the event are trying to be received and since not all #RouteScoped classes are in the current navigation chain, the above mentioned error is thrown.
Object receiver = getReceiverIfExists(null); //this is where the exception is thrown
if (receiver == null && reception != Reception.IF_EXISTS) {
// creational context is created only if we need it for obtaining receiver
// ObserverInvocationStrategy takes care of creating CC for parameters, if needed
creationalContext = beanManager.createCreationalContext(declaringBean);
receiver = getReceiverIfExists(creationalContext);
}
if (receiver != null) {
sendEvent(event, receiver, creationalContext);
}
We are not quite sure, what we are doing wrong or what we could do differently. Are we using the correct versions vaadin-cdi and Weld?
This is currently a bug in vaadin-cdi (version 14.0.0): https://github.com/vaadin/cdi/issues/390
A bugfix is already merged: https://github.com/vaadin/cdi/pull/393

Spring Boot 1.3 WebSocket JSON converter Produces Invalid JSON

After upgrading to Spring Boot 1.3 (via Grails 3.1), the JSON output is rendered incorrectly. I believe it is because of the new auto-configured WebSocket JSON converter.
For example, with previous versions of Spring Boot (via Grails 3.0), using the following code:
#MessageMapping("/chat")
#SendTo("/sub/chat")
protected String chatMessage() {
def builder = new groovy.json.JsonBuilder()
builder {
type("message")
text("foobar")
}
builder.toString()
}
This would produce:
{"type": "message", "text": "foobar"}
With Spring Boot 1.3 (via Grails 3.1), that web socket produces the following:
"{\"type\":\"message\",\"text\":\"foobar\"}"
This is not valid JSON. How can I get rid of this new behavior and have it render the JSON as it was before? Please let me know if you have any suggestions.
I tried overriding the new configureMessageConverters method, but it did not have any effect.
looks like you are right. referenced commit shows questionable autoconfiguration imho.
especially b/c in the past, the converter ordering was intentionally changed to that StringMessageConverter takes precedence before MappingJackson2MessageConverter: https://github.com/spring-projects/spring-framework/commit/670c216d3838807fef46cd28cc82165f9abaeb45
for now, you can either disable that autoconfiguration:
#EnableAutoConfiguration(exclude = [WebSocketMessagingAutoConfiguration])
class Application extends GrailsAutoConfiguration { ... }
or, you add yet another StringMessageConverter to the top of the configured converters (maybe because you do want the boot autoconfiguration behavior because it is using the jackson ObjectMapper bean instead of creating a new one):
#Configuration
#EnableWebSocketMessageBroker
class WebSocketConfig extends AbstractWebSocketMessageBrokerConfigurer {
#Override
boolean configureMessageConverters(List<MessageConverter> messageConverters) {
messageConverters.add 0, new StringMessageConverter()
return true
}
...
}
hope that helps.
I don't know how to do it in Grails but in Java you have to now pass the object instead of an object in the String class. I believe the old behavior was actually incorrect as it was returning a string as an object so there was no way to return a String that had JSON inside it as a String. So create an object with the structure you want and return it and you should be fine. I went through the same issue when upgrading from 1.2.X to 1.3.X. I am not exactly sure what change caused this but I think in the long run it is the correct thing to do.

Default constructors in Xamarin.Android

I am new to Android development with Xamarin.Android and I would like to understand how to have the next issue fixed.
Sometimes after restoring my Android application from background I was facing the next error:
Unable to find the default constructor on type MainMenuFragment. The MainMenuFragment is used by the application NavigationDrawerActivity to allow users to switch between different Fragments inside the app.
In order to solve it, I added a default constructor to the MainMenuFragment as described inside the next links:
Xamarin Limitations - 2.1. Missing constructors
Added a default constructor, should fix the issue.
public class MainMenuFragment : DialogFragment
{
readonly NavigationDrawerActivity navigationDrawer;
#region Constructors
public MainMenuFragment () {} // Default constructor...
public MainMenuFragment (NavigationDrawerActivity navigationDrawer, IMenuType launchMenu = null)
{
if (navigationDrawer == null)
throw new ArgumentNullException ("navigationDrawer");
this.navigationDrawer = navigationDrawer;
...
Fragment UpdateTopFragmentForCurrentMenu (Fragment newMenuRootFragment = null)
{
Fragment currentMenuRootFragment = navigationDrawer.CurrentFragment; // issued line.
But now sometime in the future, the MainMenuFragment gets initialized using its default constructor and at the first time it tries to access its navigationDrawer it throws a System.NullReferenceException:
System.NullReferenceException: Object reference not set to an instance of an object
at MainMenuFragment.UpdateTopFragmentForCurrentMenu (Android.App.Fragment) <0x00018>
at MainMenuFragment.OpenMenu (IMenuType,bool) <0x0006b>
at MainMenuFragment.OnCreate (Android.OS.Bundle) <0x00053>
at Android.App.Fragment.n_OnCreate_Landroid_os_Bundle_ (intptr,intptr,intptr) <0x0005b>
at (wrapper dynamic-method) object.3919a6ec-60c1-49fd-b101-86191363dc45 (intptr,intptr,intptr) <0x00043>
How can I have a default constructor implemented without facing this null reference exception?
You're programming like a C# developer, thats what the problem is :) I faced these same hurdles learning monodroid.
Take a look at the examples out there, in java, you'll see almost all the time they initialize using a static method like object.NewInstance() which returns object. This is how they initialize their views/receivers/fragments. At that point they populate the Arguments property and store that in the fragment. You need to remove all your constructors EXCEPT the empty ones and use arguments to pass your data around. If you try to do this using constructors and regular oo concepts you'll be in for a world of hurt. Arguments.putExtra and all those methods are there. It makes things a little verbose but once you get the hang of it you'll start creating some helper methods etc.
Once you get that sorted, you'll need to figure out if you need to recreate your fragments everytime the activity is resumed and if not, mark them as RetainInstance = true as well as get them onto a fragmentmanager which will help you retain all your state.
If you haven't built on android before it's weird and certainly not what I expected. But it's reeaaallly cool, much more awesome than I expected too. And same with Xamarin.
Great similar question: Best practice for instantiating a new Android Fragment

Date conversion exception inside JSF composite component

When I access a JPA managed date value from JSF, it comes back with an javax.faces.component.UdateModelException saying
'Cannot convert 01.01.10 00:00 of type class java.util.Date to class org.apache.openjpa.util.java$util$Date$proxy
Using a JPA-managed date value (which means it is proxied) works fine when it is used directly from the EL likes this:
'<h:outputLabel value="MyDateValue" for="input"/>
'<h:inputText id="inputDate" value="#{bean.myDate}"/>
However, it causes trouble when trying to use it with composite components
and gives back the following converter exception and thus can't update the model...
The (simplified) JSF composite component inputDate.xhtml
<head>
<title>A date input field</title>
</head>
<composite:interface>
<composite:attribute name="dateValue"/>
</composite:interface>
<composite:implementation>
<h:outputLabel value="MyDateValue" for="input"/>
<h:inputText id="input" value="#{cc.attrs.dateValue}"/>
</composite:implementation>
Assumption:
It seems the proxy replacement in OpenJPA is handled differently when the value is being accessed from inside a composite. My guess is the EL-resolver handles calls to object values differently when it is passed to composites. Passing it to composites means it is first accessed within the composite, which is too late and the required replacement of the proxy is not accomplished (thus the converter exception)
So I tried to change the Expression Language for MyFaces, but it didn't work in Websphere, even though I changed the class loading to parent last and provided el-impl and el-api from glassfish in the lib folder and inserted the necessary context-param for MyFaces
How do you guys use JPA-managed dates (or other proxied entities) in composite components???
If you are using the sun EL implementation you might use the following ELResolver which works around this issue:
public class BugfixELResolver extends ELResolver {
//...
#Override
public Class<?> getType(ELContext anElContext, Object aBase, Object aProperty) {
if (aBase.getClass().getCanonicalName().equals("com.sun.faces.el.CompositeComponentAttributesELResolver.ExpressionEvalMap")){
Object tempProperty=((Map)aBase).get(aProperty);
if (tempProperty!=null&&tempProperty.getClass().getCanonicalName().equals("org.apache.openjpa.util.java.util.Date.proxy")) {
anElContext.setPropertyResolved(true);
return java.util.Date.class;
}
}
return null;
}
}
Add it to the faces-config this way:
<el-resolver>
xxx.BugfixELResolver
</el-resolver>
This workaround can also be used in environments where you can not change the EL implementation (like websphere etc.).
Here is the workaround. The problem seems to be WebSpheres' ExpressionLanguage Implementation or rather the order resolvers are executed. Registering the JBoss EL implementation works and resolves the date proxies before calling the composite component. I also tried the Glassfish EL, but it didn't work either...
Registering a alternative EL is quite strange: The setting in web.xml for MyFaces is
<context-param>
<param-name>org.apache.myfaces.EXPRESSION_FACTORY</param-name>
<param-value>org.jboss.el.ExpressionFactoryImpl</param-value>
</context-param>
Additionally under WebContent/META-INF/services/ a file named javax.el.expressionFactory is needed with this single line org.jboss.el.ExpressionFactoryImpl. The class comes from jboss-el-2.0.2.CR1.jar
(sorry, couldn't find the link to a maven repo)
I will keep you updated once I find a better solution...

Why getting a 202 in two equal setup structuremap code paths

In the C# language, using StructureMap 2.5.4, targeting .NET Framework 3.5 libraries.
I've taken the step to support multiple Profiles in a structure map DI setup, using ServiceLocator model with Bootstrapper activation. First setup was loading default registry, using the scanner.
Now I like to determine runtime what Registry configuration I like to use. Scanning and loading multiple assemblies with registries.
Seems it's not working for the actual implementation (Getting the 202, default instance not found), but a stripped test version does work. The following setup.
Two assemblies containing Registries and implementations
Scanning them in running AppDomain, providing the shared Interface, and requesting Creation Of Instance, using the interfaces in constructor (which get dealt with thanx to the profile on Invokation)
Working code sample below (same structure for other setup, but with more complex stuff, that get's a 202):
What type of couses are possible for a 202, specifically naming the System.Uri type, not being handles by a default type?? (uri makes no sense)
// let structure map create instance of class tester, that provides the registered
// interfaces in the registries to the constructor of tester.
public class Tester<TPOCO>
{
private ITestMe<TPOCO> _tester;
public Tester(ITestMe<TPOCO> some)
{
_tester = some;
}
public string Exec()
{
return _tester.Execute();
}
}
public static class Main {
public void ExecuteDIFunction() {
ObjectFactory.GetInstance<Tester<string>>().Exec();
}
}
public class ImplementedTestMe<TSome> : ITestMe<TSome>
{
public string Execute()
{
return "Special Execution";
}
}
public class RegistryForSpecial : Registry
{
public RegistryForSpecial()
{
CreateProfile("Special",
gc =>
{
gc.For(typeof(ITestMe<>)).UseConcreteType(typeof(ImplementedTestMe<>));
});
}
}
Background articles on Profiles I used.
How to setup named instances using StructureMap profiles?
http://devlicio.us/blogs/derik_whittaker/archive/2009/01/07/setting-up-profiles-in-structuremap-2-5.aspx
http://structuremap.sourceforge.net/RegistryDSL.htm
EDIT:
It seemed the missing interface was actually the one being determined runtime. So here is the next challange (and solved):
I provided a default object whenever StructureMap needs to create the object. Like:
x.ForRequestedType<IConnectionContext>()
.TheDefault.Is.Object(new WebServiceConnection());
This way I got rid of the 202 error, because now a real instance could be used whever structure map needed the type.
Next was the override on runtime. That did not work out at first using the ObjectFactory.Configure method. Instead I used the ObjectFactory.Inject method to overide the default instance. Works like a charm.
ObjectFactory.Inject(typeof(IConnectionContext), context);
Loving the community effort.
Error code 202 means a default instance could not be built for the requested type. Your test code is apparently not equal to your real code that fails. If you are getting an error about Uri, you likely have a dependency that requires a Uri in its constructor. It may not be the class you are asking for - it may be one of that classes dependendencies - or one of the dependencies dependencies... somewhere down the line someone is asking StructureMap to resolve a Uri, which it cannot do, without some help from you.

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