On Wed, Aug 15, 2018 at 5:05 AM, Lyubomyr Shaydariv
<lyubomyr.shayda...@gmail.com> wrote:
> Thanks for the reply, Tatu.
>
> Unfortunately, 2.6.7 works exactly the same like 2.6.3 does. However, if I
> switch to 2.9.6 (and I hope I'll migrate the project I work at too), the
> output is slightly different: `class com.sun.proxy.$Proxy0`. The assertion
> error is never thrown though.
Hmmh. Looking at that, although I am not familiar with usage of Proxy
instances, it seems to me that
behavior here makes sense -- nothing in code is triggering any of
accessors so no exception is thrown.
Usage of Proxy here does not actually matter, as databind is not
really (nor needs to be) aware of its use.
Shouldn't code try to call `getName()` to trigger exception or something?
All Jackson does is invoke `deserialize()` method, which invokes
creation of proxied instance. But since
custom deserializes are expected to handle all actual deserialization
logic, including reading of JSON value
and setting values of Java object created, there is no other action.
I am guessing you might be expecting that only instance was created,
and then Jackson would handle content,
call setters, in which case exception would be expected. This is
possible using `ValueInstantiator` handler, although
bit more work. But plain `JsonDeserializer` delegates all work from databind.
I hope this makes sense.
-+ Tatu +-
>
>
> On Wednesday, August 15, 2018 at 1:58:14 PM UTC+3, Tatu Saloranta wrote:
>>
>> On Tue, Aug 14, 2018 at 1:30 PM, Lyubomyr Shaydariv
>> <lyubomyr....@gmail.com> wrote:
>> > Hello,
>> >
>> > I've faced with an issue where I need to work with dynamic proxies since
>> > I
>> > find them a very convenient way allowing to reduce the amount of code
>> > dramatically. Please consider the following code:
>> >
>> > interface IUserDto {
>> >
>> > @JsonProperty(value = "name", access = JsonProperty.Access.READ_ONLY)
>> > String getName();
>> >
>> > void setName(String name);
>> >
>> > interface IUserCreateDto
>> > extends IUserDto {
>> >
>> > @JsonProperty(value = "name", access = JsonProperty.Access.WRITE_ONLY,
>> > required = true)
>> > void setName(String name);
>> >
>> > }
>> >
>> > static void main(final String... args)
>> > throws IOException {
>> > final ClassLoader classLoader = IUserDto.class.getClassLoader();
>> > final ObjectMapper objectMapper = new ObjectMapper();
>> > objectMapper.registerModule(new SimpleModule()
>> > .addDeserializer(IUserCreateDto.class, new
>> > JsonDeserializer<IUserCreateDto>() {
>> > @Override
>> > public IUserCreateDto deserialize(final JsonParser parser, final
>> > DeserializationContext context) {
>> > return (IUserCreateDto) Proxy.newProxyInstance(classLoader, new Class[]{
>> > IUserCreateDto.class }, (proxy, method, args) -> {
>> > throw new AssertionError("This never happens");
>> > });
>> > }
>> > })
>> > );
>> > final IUserCreateDto userCreateDto =
>> > objectMapper.readValue("{\"name\":\"John\"}", IUserCreateDto.class);
>> > System.out.println(userCreateDto.getClass());
>> > }
>> >
>> > }
>> >
>> >
>> >
>> > For some reason, the invocation handler defined for the proxy is never
>> > invoked. Hence, the last System.out.println() simply prints `class
>> > com.sun.proxy.$Proxy2`, but I would expect the `readValue` method to
>> > fail
>> > because of the intentional assertion error specified in the invocation
>> > handler. My question is: what am I doing wrong and if it's possible to
>> > make
>> > Jackson work with dynamic proxies?
>> >
>> > Here are my Jackson dependencies:
>> >
>> > * com.fasterxml.jackson.core:jackson-core:2.6.3
>> > * com.fasterxml.jackson.core:jackson-databind:2.6.3
>>
>> As usual, I would suggest trying out:
>>
>> 1. The last path version of minor version you have: 2.6.7; if same
>> behavior
>> 2. Try one of later maintained versions: either 2.8.11 or .29.6
>>
>> to verify issue still exists, as 2.6.3 is bit old version and there
>> have been more fixes.
>>
>> Proxy types are not supported by default for deserialization, but
>> custom deserializers should work I think.
>> If later versions do not work (which seem likely), I would file an
>> issue at github against `jackson-databind`.
>>
>> -+ Tatu +-
>
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