I've a java binding for android which somewhat works bar the new feature I'm trying to integrate with. Only now I have realised that the intended callback is not happening. Here are the classes (decompiled to java) in question:
At the top level we have
public interface MyPackage {
MyPackage.Companion Companion = MyPackage.Companion.$$INSTANCE;
public static final class Companion {
#Nullable
private static MyEventHandler myEventHandler;
// $FF: synthetic field
static final MyPackage.Companion $$INSTANCE;
#Nullable
public final MyEventHandler getMyEventHandler() {
return myEventHandler;
}
public final void setMyEventHandler(#Nullable MyEventHandler var1) {
myEventHandler = var1;
}
private Companion() {
}
static {
MyPackage.Companion var0 = new MyPackage.Companion();
$$INSTANCE = var0;
}
}
}
MyEventHandler class:
public abstract class MyEventHandler {
public abstract void handleEvent(#NotNull String var1, #NotNull Properties var2);
}
Properties class:
import java.util.Map;
public class Properties extends r {
public Properties() {
}
Properties(Map<String, Object> var1) {
super(var1);
}
public Properties a(String var1, Object var2) {
super.b(var1, var2);
return this;
}
}
and the problematic r class:
public class r implements Map<String, Object> {
private final Map<String, Object> a;
various implementations...
}
So I noticed the issue when I couldnt override the HandleEvent method at the integration level and started looking at the Binding logs and found:
Warning=>
BINDINGSGENERATOR: Warning BG8801: Invalid parameter type MyPackage...Properties in method HandleEvent in managed type MyPackage.MyEventHandler. (BG8801)
And in build logs:
message BG0000: warning BG8102: Class MyPackage....Properties has unknown base type MyPackage....r.
warning BG8801: Invalid parameter type MyPackage...Properties in method HandleEvent in managed type MyPackage.MyEventHandler.
As it was obvious r is an obfuscated class I need to make chagnes to my Metadata so I went ahead and popped in:
<attr path="/api/package[#name='MyPackage']/class[#name='r']" name="obfuscated">false</attr>
Which resulted in the R being generated but now I get the 5 following compile error:
Error CS0535: 'R' does not implement interface member 'IMap.EntrySet()' (CS0535)
Error CS0738: 'R' does not implement interface member 'IMap.KeySet()'. 'R.KeySet()' cannot implement 'IMap.KeySet()' because it does not have the matching return type of 'ICollection'. (CS0738)
Error CS0535: 'R' does not implement interface member 'IMap.Put(Object?, Object?)' (CS0535)
Error CS0535: 'R' does not implement interface member 'IMap.PutAll(IDictionary?)' (CS0535)
Error CS0738: 'R' does not implement interface member 'IMap.Values()'. 'R.Values()' cannot implement 'IMap.Values()' because it does not have the matching return type of 'ICollection'. (CS0738)
I tried to make a managed return using
<attr path="/api/package[#name='MyPackage']/class[#name='r']/method[#name='entrySet' and count(parameter)=0]" name="managedReturn">Java.Util.IMap</attr>
With same number of compile error as above. Then I tried removing the node using:
<remove-node path="/api/package[#name='MyPackage']/class[#name='r']/method[#name='entrySet']"/>
Still no luck. :(
What am I missing here? Any pointers/suggestions will be appreciated!
It seems like you are trying to expose a Map to C# and as you stated, Java Generics are not handled very well.
In a very popular social network you received an answer from #mattleibow. I do not take credit for his answer but I went to check nonetheless and it seems fine.
If you look at the description of the Java.Lang.HashMap type
https://learn.microsoft.com/en-us/dotnet/api/java.util.hashmap?view=xamarin-android-sdk-9 it's a good candidate for you to expose.
You can also try with the corresponding interface for better safety https://learn.microsoft.com/en-us/dotnet/api/java.util.imap?view=xamarin-android-sdk-9
If it works you will still have to cast the types yourself.
Please answer to the comment to say that problem is solved for the sake of future generations arriving on this post :D
Credit is not mine so don't give it to me :-)
John,
I got arround fixing it by providing implementation of the the said methods in a partial class. Basically added a new file called R.cs under Additions folder as follows:
namespace YourNameSpace
{
public partial class R
{
public void PutAll(System.Collections.IDictionary p0)
{
PutAll(p0);
}
public Java.Lang.Object Put(Java.Lang.Object key, Java.Lang.Object value)
{
return Put(key, value);
}
public System.Collections.ICollection EntrySet()
{
return EntrySet();
}
public System.Collections.ICollection KeySet()
{
return KeySet();
}
public System.Collections.ICollection Values()
{
return Values();
}
}
}
I couldn't get it to work by adding XML transformation, but I think there was some tooling issue.
Related
I want to return list of interfaces with different implementations by calling query/mutation in grpahql spqr.
For this purpose I suppose I need to use #GraphQLInterface.
Maybe I doing something wrong, but it not works.
I have spring-boot app 2.3.3.RELEASE with graphql-spqr-spring-boot-starter 0.0.4
There is my model:
public class ResponseDto {
...
List<IValidation> validations;
}
#GraphQLInterface(name = "ValidationError", implementationAutoDiscovery = true)
public interface ValidationError {
#GraphQLQuery(name = "message")
String getMessage();
}
#GraphQLType(name = "SimpleError")
#AllArgsConstructor
#Getter
public enum SimpleError implements ValidationError {
ERROR("some msg");
private String message;
}
But when I get graphql schema there is no any info about SimpleError and field message in ValidationError.
I also tried without GraphQLType and GraphQLQuery, it not works.
And I tried with no enum implementation also, same result.
Could anyone explain what I'm doing wrong?
Thank you.
This question already has answers here:
How to make a Java class that implements one interface with two generic types?
(9 answers)
Closed 8 years ago.
I have the following interface, which I want to implement multiple times in my classes:
public interface EventListener<T extends Event>
{
public void onEvent(T event);
}
Now, I want to be able to implement this interface in the following way:
class Foo implements EventListener<LoginEvent>, EventListener<LogoutEvent>
{
#Override
public void onEvent(LoginEvent event)
{
}
#Override
public void onEvent(LogoutEvent event)
{
}
}
However, this gives me the error: Duplicate class com.foo.EventListener on the line:
class Foo implements EventListener<LoginEvent>, EventListener<LogoutEvent>
Is it possible to implement the interface twice with different generics? If not, what's the next closest thing I can do to achieve what I'm trying to do here?
Is it possible to implement the interface twice with different generics
Unfortunately no. The reason you can't implement the same interface twice is because of type erasure. The compiler will handle type parameters, and a runtime EventListener<X> is just a EventListener
If not, what's the next closest thing I can do to achieve what I'm trying to do here?
Type erasure can work in our favor. Once you know that EventListener<X> and EventListener<Y> are just raw EventListener at run-time, it is easier than you think to write an EventListener that can deal with different kinds of Events. Bellow is a solution that passes the IS-A test for EventListener and correctly handles both Login and Logout events by means of simple delegation:
#SuppressWarnings("rawtypes")
public class Foo implements EventListener {
// Map delegation, but could be anything really
private final Map<Class<? extends Event>, EventListener> listeners;
// Concrete Listener for Login - could be anonymous
private class LoginListener implements EventListener<LoginEvent> {
public void onEvent(LoginEvent event) {
System.out.println("Login");
}
}
// Concrete Listener for Logout - could be anonymous
private class LogoutListener implements EventListener<LogoutEvent> {
public void onEvent(LogoutEvent event) {
System.out.println("Logout");
}
}
public Foo() {
#SuppressWarnings("rawtypes")
Map<Class<? extends Event>, EventListener> temp = new HashMap<>();
// LoginEvents will be routed to LoginListener
temp.put(LoginEvent.class, new LoginListener());
// LogoutEvents will be routed to LoginListener
temp.put(LogoutEvent.class, new LogoutListener());
listeners = Collections.unmodifiableMap(temp);
}
#SuppressWarnings("unchecked")
#Override
public void onEvent(Event event) {
// Maps make it easy to delegate, but again, this could be anything
if (listeners.containsKey(event.getClass())) {
listeners.get(event.getClass()).onEvent(event);
} else {
/* Screams if a unsupported event gets passed
* Comment this line if you want to ignore
* unsupported events
*/
throw new IllegalArgumentException("Event not supported");
}
}
public static void main(String[] args) {
Foo foo = new Foo();
System.out.println(foo instanceof EventListener); // true
foo.onEvent(new LoginEvent()); // Login
foo.onEvent(new LogoutEvent()); // Logout
}
}
The suppress warnings are there because we are "abusing" type erasure and delegating to two different event listeners based on the event concrete type. I have chosen to do it using a HashMap and the run-time Event class, but there are a lot of other possible implementations. You could use anonymous inner classes like #user949300 suggested, you could include a getEventType discriminator on the Event class to know what do to with each event and so on.
By using this code for all effects you are creating a single EventListener able to handle two kinds of events. The workaround is 100% self-contained (no need to expose the internal EventListeners).
Finally, there is one last issue that may bother you. At compile time Foo type is actually EventListener. Now, API methods out of your control may be expecting parametrized EventListeners:
public void addLoginListener(EventListener<LoginEvent> event) { // ...
// OR
public void addLogoutListener(EventListener<LogoutEvent> event) { // ...
Again, at run-time both of those methods deal with raw EventListeners. So by having Foo implement a raw interface the compiler will be happy to let you get away with just a type safety warning (which you can disregard with #SuppressWarnings("unchecked")):
eventSource.addLoginListener(foo); // works
While all of this may seem daunting, just repeat to yourself "The compiler is trying to trick me (or save me); there is no spoon <T>. Once you scratch your head for a couple of months trying to make legacy code written before Java 1.5 work with modern code full of type parameters, type erasure becomes second nature to you.
You need to use inner or anonymous classes. For instance:
class Foo {
public EventListener<X> asXListener() {
return new EventListener<X>() {
// code here can refer to Foo
};
}
public EventListener<Y> asYListener() {
return new EventListener<Y>() {
// code here can refer to Foo
};
}
}
This is not possible.
But for that you could create two different classes that implement EventListener interface with two different arguments.
public class Login implements EventListener<LoginEvent> {
public void onEvent(LoginEvent event) {
// TODO Auto-generated method stub
}
}
public class Logout implements EventListener<LogoutEvent> {
public void onEvent(LogoutEvent event) {
// TODO Auto-generated method stub
}
}
I have an aggregate root like this:
Aggregate root:
#NoArgsConstructor
#Aggregate(repository = "positionAggregateRepository")
#AggregateRoot
#XSlf4j
#Data
public class HopAggregate {
#AggregateIdentifier
private String hopId;
private FilteredPosition position;
private LocalDate positionDate;
#AggregateMember
private Security security;
#CommandHandler
public HopAggregate(NewHopCommand cmd) {
log.info("creating new position , {}", cmd.getDateId());
apply(new HopEvent(cmd.getHopId(), cmd.getDateId(), cmd.getFilteredPosition(), cmd.getSecurity(), false));
}
#CommandHandler
public void handle(UpdateHopCommand cmd) {
log.info("creating hop update event {}", cmd);
apply(new HopEvent(this.hopId, this.positionDate, cmd.getFilteredPosition(), this.security, true));
}
#CommandHandler
public void handle(SecurityUpdate cmd) {
log.info("updating security {}", cmd);
apply(new SecurityUpdateEvent(this.hopId, cmd.getFilteredSecurity()));
}
#EventSourcingHandler
public void on(HopEvent evt) {
if (evt.getIsUpdate()) {
log.info("updating position {}", evt);
this.position = evt.getFilteredPosition();
} else {
log.info("adding new position to date {}", evt);
this.hopId = evt.getHopId();
this.positionDate = evt.getDate();
this.position = evt.getFilteredPosition();
this.security= evt.getSecurity();
}
}
#EventSourcingHandler
public void on(SecurityUpdateEvent evt) {
log.info("hop id {}, security update {}", this.hopId, evt.getFilteredSecurity().getSecurityId());
}
}
Child entity:
#XSlf4j
#Data
#RequiredArgsConstructor
#NoArgsConstructor
public class IpaSecurity implements Serializable {
#EntityId
#NonNull
private String id;
#NonNull
private FilteredSecurity security;
}
My issue is that when i am pushing and update like this:
#EventHandler
public void handleSecurityEvent(SecurityUpdate securityUpdate) {
log.info("got security event {}", securityUpdate);
commandGateway.send(securityUpdate);
}
and my command being:
#Data
#RequiredArgsConstructor
#NoArgsConstructor
#ToString
public class SecurityUpdate {
#NonNull
#TargetAggregateIdentifier
private String id;
#NonNull
private FilteredSecurity filteredSecurity;
}
I am getting aggregate root not found exception:
Command 'com.hb.apps.ipa.events.SecurityUpdate' resulted in org.axonframework.modelling.command.AggregateNotFoundException(The aggregate was not found in the event store)
I am not sure how to handle this scenario. My requirement is that each aggregate should check whether it contains the security and then update it if the command was issued. What am i missing? let me know if you need any more info on the code.
Thanks for your help.
A Command is always targeted towards a single entity.
This entity can be an Aggregate, an entity contained in an Aggregate (what Axon Framework calls an Aggregate Member) or a simple singleton component.
Important to note though, is that there will only be one entity handling the command.
This is what requires you to set the #TargetAggregateIdentifier in your Command for Axon to be able to route it to a single Aggregate instance if the Command Handler in question is part of it.
The AggregateNotFoundException you're getting signals that the #TargetAggregateIdentifier annotated field in your SecurityUpdate command does no correspond to any existing Aggregate.
I'd thus suspect that the id field in the SecurityUpdate does not correspond to any #AggregateIdentifier annotated field in your HopAggregate aggregates.
A part from the above, I have a couple of other suggestions when looking at your snippets which I'd like to share with you:
#Aggregate is meta-annotated with #AggregateRoot. You're thus not required to specify both on an Aggregate class
For logging messages being handled, you can utilize LoggingInterceptor. You can configure this on any component capable of handling messages, thus providing a universal way of logging. This will omit the necessity to add log lines in your message handling functions
You're publishing a HopEvent on both the create and update commands. Doing so makes your HopEvent very generic. Ideally, your events clarify business operations occurring in your system. My rule of thumb typically is such: "If I tell my business manager/customer about the event class, he/she should know exactly what it does". I'd thus suggest to rename the event to something more specific
Just as with the HopEvent, the UpdateHopCommand is quite generic. Your commands should express the intent to perform an operation in your application. Users will typically not desire an update, they desire an address change for example. Your commands classes ideally reflect this
The suggested naming convention for commands is to start with verb in the present tense. Thus, it should no be SecurityUpdate, but UpdateSecurity. A command is a request expressing intent, the messages ideally reflect this
Hope this helps you out #juggernaut!
Mapper decorator for my mapper is not getting compiled.Mapper is getting compiled, but not the decorator. Because, during the build I'm getting the type conversion error, even though I'm doing it in the mapper decorator. Is there anything more to add?
mapper code:
#Mapper
#DecoratedWith(OneMapperDecorator.class)
public interface OneMapper {
public TwoObject convertToTwoObject(OneObject one);
}
decorator code:
public abstract class OneMapperDecorator implements OneMapper {
private final OneMapper delegate;
public OneMapperDecorator (OneMapper delegate) {
this.delegate = delegate;
}
#Override
public TwoObject convertToTwoObject(OneObject one)
{
TwoObject two=delegate.convertToTwoObject(one);
two.setTotalFare(new BigDecimal(one.getPrice()));//string to bigdecimal conversion
return two;
}
}
The decorator is meant to augment the mapping not to replace it. MapStruct has no way of knowing that you are mapping your totalFare in the decorator. You have 2 options:
Define a custom mapping method
In your OneMapper you can add a default method that would perform the mapping (as the error says.
#Mapper
#DecoratedWith(OneMapperDecorator.class)
public interface OneMapper {
#Mapping(target = "totalFare", source = "price");
TwoObject convertToTwoObject(OneObject one);
default BigDecimal map(String value) {
return value == null ? null : new BigDecimal(value);
}
}
Ignore the mapping
In case you want to do the mapping in your decorator then you need to tell MapStruct to not map it.
#Mapper
#DecoratedWith(OneMapperDecorator.class)
public interface OneMapper {
#Mapping(target = "totalFare", ignore = true);
TwoObject convertToTwoObject(OneObject one);
}
One advise from me if you are using your delegate only to map extra fields I would either add custom methods or use #AfterMapping and #BeforeMapping to handle that.
I'm pretty new to MVVM light world, and after searches I can't find what I want to do.
My WP7 application contains a pivot, each pivot item content is View1 and viewmodel is VM1.
When loading my application, I'd like to create every pivot item with the same view and view model but with different parameter.
example :
PivotItem 1 -> send param "car" to the view model
PivotItem 2 -> send param "truck" to the view model, etc.
Google told me to use messaging but if I send 2 messages from my MainViewModel, both PivotItem1 and PivotItem2 ViewModel will receive these messages.
Am I wrong with this approach ?
Is there another solution to succeed ?
Thank you in advance for your answer.
PS : be indulgent, english is not my native language, don't hesitate to ask for further information.
Regards,
Aymeric Lagier
To seperate the messages use the second constructor signature whereby you can pass a token. This token can be anything but I generally use an enum to store all my message types within the system.
Create a static class in a common library and reference this in all projects where you need to send or receive messages.
The following code hopefully shows this approach, notice I am sending a string as a value within the message but this can be anything, even a complex object such as one of your business objects.
namespace MyProject.Common
{
public static class AppMessages
{
enum MessageTypes
{
ViewmodelA,
ViewmodelB
}
public static class ViewModelAUpdate
{
public static void Send(string value)
{
Messenger.Default.Send(value, MessageTypes.ViewmodelA);
}
public static void Register(object recipient, Action<string> action)
{
Messenger.Default.Register(recipient, MessageTypes.ViewmodelA, action);
}
}
public static class ViewModelBUpdate
{
public static void Send(string value)
{
Messenger.Default.Send(value, MessageTypes.ViewmodelB);
}
public static void Register(object recipient, Action<string> action)
{
Messenger.Default.Register(recipient, MessageTypes.ViewmodelB, action);
}
}
}
}
How about using a method to set the message you want to receive. (this could be done as a parameter in the constructor or a property as well)
public void RegisterForAppMessage(AppMessages.MessageTypes messageType)
{
switch (messageType)
{
case AppMessages.MessageTypes.PivotViewItem1Message:
AppMessages.PivotViewItem1Message.Register(this,DoSomethingWhenIRecievePivotViewItem1Messages)
break;
case AppMessages.MessageTypes.PivotViewItem2Message:
AppMessages.PivotViewItem2Message.Register(this,DoSomethingWhenIRecievePivotViewItem2Messages)
break;
}
}
private void DoSomethingWhenIRecievePivotViewItem2Messages(string obj)
{
// TODO: Implement this method
throw new NotImplementedException();
}
private void DoSomethingWhenIRecievePivotViewItem1Messages(string obj)
{
// TODO: Implement this method
throw new NotImplementedException();
}
Messaging sounds a bit heavy for this purpose. Could you simply inject a parameter into your ViewModel. If you already have MVVMLight you also have support for SimpleIOC. Maybe let the view locate its ViewModel when the view is resolved and there decide which parameter to use on the view model?
You can see an example of it here