JSON deserialization issue of selfservice API in Java SDK

[ghost]

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• I could not find a solution in the existing issues, docs, nor discussions.
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Describe the bug

We have just started evaluating Ory Kratos and Ory Cloud as a cloud service for us.
I´m currently working with Ory Kratos Java SDK, to get connected via API to Ory Cloud v0.8.3-alpha.1.pre.0.0.20220221123934-668f6b246db1 and got into a JSON deserialization error. I´m trying to initializeSelfServiceLoginFlowWithoutBrowser() of V0alpha2API, where I get a java.lang.IllegalArgumentException: field sh.ory.kratos.model.UiNode.attributes has type sh.ory.kratos.model.UiNodeAttributes, got sh.ory.kratos.model.UiNodeInputAttributes. It looks pretty close to #75 .
#75 was solved with Ory Kratos v0.7. I have checked several versions of Ory Kratos v0.7 Java SDK, which worked as expected, but with v0.8.0-alpha2 and newer I see the IllegalArgumentException again.

Reproducing the bug

Kratos Java SDK

1. init API client: ApiClient apiClient = Configuration.getDefaultApiClient();
2. set path, e.g.: apiClient.setBasePath("https://playground.projects.oryapis.com/api/kratos/public");
3. init V0alpha2API: V0alpha2Api oryApiAlpha2 = new V0alpha2Api(apiClient);
4. init self service login flow: oryApiAlpha2.initializeSelfServiceLoginFlowWithoutBrowser(null, null, null);

Relevant log output

W/System.err: java.lang.IllegalArgumentException: field sh.ory.kratos.model.UiNode.attributes has type sh.ory.kratos.model.UiNodeAttributes, got sh.ory.kratos.model.UiNodeInputAttributes
W/System.err:     at java.lang.reflect.Field.set(Native Method)
W/System.err:     at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.read(ReflectiveTypeAdapterFactory.java:133)
W/System.err:     at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:222)
W/System.err:     at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.read(TypeAdapterRuntimeTypeWrapper.java:41)
W/System.err:     at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:82)
W/System.err:     at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:61)
W/System.err:     at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.read(ReflectiveTypeAdapterFactory.java:131)
W/System.err:     at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:222)
W/System.err:     at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.read(ReflectiveTypeAdapterFactory.java:131)
W/System.err:     at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:222)
W/System.err:     at com.google.gson.Gson.fromJson(Gson.java:932)
W/System.err:     at com.google.gson.Gson.fromJson(Gson.java:897)
W/System.err:     at com.google.gson.Gson.fromJson(Gson.java:846)
W/System.err:     at sh.ory.kratos.JSON.deserialize(JSON.java:232)
W/System.err:     at sh.ory.kratos.ApiClient.deserialize(ApiClient.java:795)
W/System.err:     at sh.ory.kratos.ApiClient.handleResponse(ApiClient.java:1001)
W/System.err:     at sh.ory.kratos.ApiClient.execute(ApiClient.java:925)
W/System.err:     at sh.ory.kratos.api.V0alpha2Api.initializeSelfServiceLoginFlowWithoutBrowserWithHttpInfo(V0alpha2Api.java:2349)
W/System.err:     at sh.ory.kratos.api.V0alpha2Api.initializeSelfServiceLoginFlowWithoutBrowser(V0alpha2Api.java:2326)

Relevant configuration

No response

Version

v0.8.0-alpha2 and newer

On which operating system are you observing this issue?

Linux

In which environment are you deploying?

No response

Additional Context

No response

[ghost]

It seems to be related with the "discriminator" updates in ".schema/openapi/patches/schema.yaml" of commit 59e808e8dc6339da59bbe08ebbcf7b840e3fdd50 (Ory Kratos repo).
If I remove the following:

.registerTypeSelector(UiNodeAttributes.class, new TypeSelector<UiNodeAttributes>() {
                    @Override
                    public Class<? extends UiNodeAttributes> getClassForElement(JsonElement readElement) {
                        Map<String, Class> classByDiscriminatorValue = new HashMap<String, Class>();
                        classByDiscriminatorValue.put("anchor", UiNodeAnchorAttributes.class);
                        classByDiscriminatorValue.put("image", UiNodeImageAttributes.class);
                        classByDiscriminatorValue.put("input", UiNodeInputAttributes.class);
                        classByDiscriminatorValue.put("script", UiNodeScriptAttributes.class);
                        classByDiscriminatorValue.put("text", UiNodeTextAttributes.class);
                        classByDiscriminatorValue.put("uiNodeAnchorAttributes", UiNodeAnchorAttributes.class);
                        classByDiscriminatorValue.put("uiNodeImageAttributes", UiNodeImageAttributes.class);
                        classByDiscriminatorValue.put("uiNodeInputAttributes", UiNodeInputAttributes.class);
                        classByDiscriminatorValue.put("uiNodeScriptAttributes", UiNodeScriptAttributes.class);
                        classByDiscriminatorValue.put("uiNodeTextAttributes", UiNodeTextAttributes.class);
                        classByDiscriminatorValue.put("uiNodeAttributes", UiNodeAttributes.class);
                        return getClassByDiscriminator(classByDiscriminatorValue,
                                getDiscriminatorValue(readElement, "node_type"));
                    }
          })

generated java code in "kratos-client-java/src/main/java/sh/ory/kratos/JSON.java" below:

public static GsonBuilder createGson() {
        GsonFireBuilder fireBuilder = new GsonFireBuilder()

and compile Java SDK with Maven mvn clean package, it is working.

With this workaround it seems that it is working for my current SDK evaluation purpose, but wouldn´t be useful for a release.

[ghost]

I changed library to jersey2. With this library it is working without the discriminator problem

[Empyreans]

Could you please elaborate how exactly you fixed the problem? You switched the Json library?

[aeneasr]

Which one is the recommended generator for Java? We can also update it if that generator is less buggy

[ghost]

The underlying openapi-generator supports several http libraries for java (see "library" at openapi-generator.tech). Default is "okhttp-gson" which causes the discriminator problems in my case.
In "sdk" section of Ory Kratos Makefile (Ory Kratos root directory), there is a call of "openapi-generator-cli". I added the jersey2 library.
It looks now as following (I added the "--additional-properties..." line):

npm run openapi-generator-cli -- generate -i "spec/api.json" \
    -g java \
    -o "internal/httpclient" \
    --additional-properties=library=jersey2 \

I hope this helps to unserstand what I did.

Jersey2 was working in my case. I´m not sure if it makes sense as a general solution

[aeneasr]

Thank you for the reply! Switching generators is a possibility. Unfortunately I have very little experience with Java and don’t really know what libraries are en vogue and which ones aren’t. It also depends a bit on the support of the generator in the openapi tooling. @piotrmsc do you have experience with these libs in Java?

[notmeta]

Getting this too, noticed it only happens with null/"aal1" as aal parameters in the initialisation function, otherwise there are other errors (e.g. bad request for invalid session token).

[dstockhammer]

I think jackson would be a safer choice for the serializer. Not entirely sure why the generator uses okhttp-gson as default, but I'd assume it's for backwards-compatibility since changing any of the underlying libraries would be a breaking change.

For the HTTP client on the other hand I don't think there's a clear winner. native might be a good alternative, but that would require Java 11 which is probably not acceptable. Since the default is okhttp the safest choice is probably to leave it at that 🤷

So if you'd be willing to change the serializationLibrary to jackson I think that would be an improvement for most use cases. Though it's a breaking change that can cause problems depending on how the library is used and what other libraries there are in the project.

[aeneasr]

Can anyone confirm that this is still an issue?

[ghost]

No response yet and I´m currently working on other projects. I will close this issue.