Implementation in gson deserialization to able deserialize generics parameters

[dtelaroli]

The GsonDeserialization not is able to deserialize generics parameters like this:

class GenericCtrl {
void method(T type)
}
class ExtendedCtrl extends GenericCtrl{
}

edit: removed the old description

[lucascs]

It's a little too specific... We don't need to create a new annotation for this... It is possible to discover the generic type if you have a subclass:

public class DogController extends GenericController<Dog> {...}

Class<?> dogClass = DogController.class.getGenericSuperclass().getGenericTypeArguments[0];

[dtelaroli]

Ok, I change to keep simple after your recommendation.
I don't think that generics is too specific, but I'm learning that generics is the cause of many problems in our software design.

Now it is able to deserialize generics, if method type is equal to generics types.

[lucascs]

I don't think this is the right test...

you should do something like if (superclass instanceof ParameterizedType)

[dtelaroli]

Done

[lucascs]

Just to point it out: It won't cover the case when the generic controller method receives more than one argument:

public class GenericController<T> {
    public void save(T obj, String something) {...}
}

[dtelaroli]

the deserializer will deserialize only the first ParameterizedType, so, will be possible add arguments after the generic type if the GenericController has more than one.
are you agree?

[lucascs]

Not really...
the GSon deserializer supports deserializing multiple parameters:

{ "user": { "name": "jao", "email": "[email protected]" },
  "something" : "else" }

[dtelaroli]

in the last commit is require that it everytime make overlay of the first parameter, forming a convention.

I think that we can to create a boolean property in @consumes annotation, with default false, to enable this feature, just when to need.
what do you think?

the name property could be same enableGenericsOverlay.

[lucascs]

As far as I know, if you don't have a root, it tries do deserialize to the first argument. But if you have a root, with the names of the parameters, you can deserialize as many properties as you want.

I don't like changing the @Consumes annotation because of generics... I don't like using generic controllers either ;)

The point is, even supporting multiple parameters and the Generic parameter, it's possible to know which parameter is the generic one. If I'm not wrong:

Type[] parameterTypes = method.getGenericParameterTypes();

for (Type type : parameterTypes) {
   if (type instanceof TypeVariable)
      // use the controller generic type
   else
      // use type
}

[dtelaroli]

We need compare parameter with TypeArgumet

if(parameterTypes[i].isAssignableFrom(type.getClass())) {
    parameterTypes[i] = (Class<?>) type;
}

to me is working fine
can you check?

[lucascs]

Write a test for it =) If the tests are green It works =)

[lucascs]

I'd extract the generic extraction to a method:

Class<?>[] parameterTypes = method.getMethod().getParameterTypes();
Type genericType = getGenericType(method.getResource().getType);
if (genericType != null) {
    for ...
}
return parameterTypes;

[dtelaroli]

the tests are
shouldDeserializeFromGenericTypeOneParam
shouldDeserializeFromGenericTypeTwoParams
shouldDeserializeWithoutGenericType

[lucascs]

method.getMethod() is already clear. You don't need to extract this method. Please get back to method.getMethod()

[lucascs]

I hope you are not getting upset, coding with reflection is always messy :P

[dtelaroli]

relax man, I just did not understand
me too want the better code, but I have much to learn

[dtelaroli]

verify please

[lucascs]

Merged, thanks! =)

[dtelaroli]

thank you too

[lucascs]

In fact, the line parameterTypes[i].isAssignableFrom(genericType) was working because parameterTypes[i] is Object.class for the generic type, so it is assignable from all the classes... I'm fixing it =/

[lucascs]

Take a look: 9c5a0a8