Introduce declarative support for Custom Jackson Serialization

extensions/resteasy-reactive/quarkus-resteasy-reactive-jackson/deployment/src/main/java/io/quarkus/resteasy/reactive/jackson/deployment/processor/ResteasyReactiveJacksonProcessor.java

@@ -8,19 +8,24 @@
 
 import javax.ws.rs.core.MediaType;
 
+import org.jboss.jandex.AnnotationInstance;
+import org.jboss.jandex.AnnotationValue;
 import org.jboss.jandex.ClassInfo;
 import org.jboss.jandex.DotName;
+import org.jboss.jandex.Type;
 
 import com.fasterxml.jackson.annotation.JsonView;
 
 import io.quarkus.arc.deployment.AdditionalBeanBuildItem;
 import io.quarkus.deployment.Feature;
 import io.quarkus.deployment.annotations.BuildProducer;
 import io.quarkus.deployment.annotations.BuildStep;
+import io.quarkus.deployment.builditem.CombinedIndexBuildItem;
 import io.quarkus.deployment.builditem.FeatureBuildItem;
 import io.quarkus.deployment.builditem.nativeimage.ReflectiveClassBuildItem;
 import io.quarkus.resteasy.reactive.common.deployment.ResourceScanningResultBuildItem;
 import io.quarkus.resteasy.reactive.common.deployment.ServerDefaultProducesHandlerBuildItem;
+import io.quarkus.resteasy.reactive.jackson.CustomSerialization;
 import io.quarkus.resteasy.reactive.jackson.runtime.serialisers.JacksonMessageBodyReader;
 import io.quarkus.resteasy.reactive.jackson.runtime.serialisers.JacksonMessageBodyWriter;
 import io.quarkus.resteasy.reactive.spi.MessageBodyReaderBuildItem;
@@ -29,6 +34,7 @@
 public class ResteasyReactiveJacksonProcessor {
 
     private static final DotName JSON_VIEW = DotName.createSimple(JsonView.class.getName());
+    private static final DotName CUSTOM_SERIALIZATION = DotName.createSimple(CustomSerialization.class.getName());
 
     @BuildStep
     void feature(BuildProducer<FeatureBuildItem> feature) {
@@ -59,7 +65,8 @@ void additionalProviders(BuildProducer<AdditionalBeanBuildItem> additionalBean,
     }
 
     @BuildStep
-    void registerForReflection(Optional<ResourceScanningResultBuildItem> resourceScanningResultBuildItem,
+    void handleJsonAnnotations(Optional<ResourceScanningResultBuildItem> resourceScanningResultBuildItem,
+            CombinedIndexBuildItem index,
             BuildProducer<ReflectiveClassBuildItem> reflectiveClass) {
         if (!resourceScanningResultBuildItem.isPresent()) {
             return;
@@ -68,8 +75,28 @@ void registerForReflection(Optional<ResourceScanningResultBuildItem> resourceSca
                 .values();
         Set<String> classesNeedingReflectionOnMethods = new HashSet<>();
         for (ClassInfo resourceClass : resourceClasses) {
+            DotName resourceClassDotName = resourceClass.name();
             if (resourceClass.annotations().containsKey(JSON_VIEW)) {
-                classesNeedingReflectionOnMethods.add(resourceClass.name().toString());
+                classesNeedingReflectionOnMethods.add(resourceClassDotName.toString());
+            } else if (resourceClass.annotations().containsKey(CUSTOM_SERIALIZATION)) {
+                classesNeedingReflectionOnMethods.add(resourceClassDotName.toString());
+                for (AnnotationInstance instance : resourceClass.annotations().get(CUSTOM_SERIALIZATION)) {
+                    AnnotationValue annotationValue = instance.value();
+                    if (annotationValue != null) {
+                        Type biFunctionType = annotationValue.asClass();
+                        ClassInfo biFunctionClassInfo = index.getIndex().getClassByName(biFunctionType.name());
+                        if (biFunctionClassInfo == null) {
+                            // be lenient
+                        } else {
+                            if (!biFunctionClassInfo.hasNoArgsConstructor()) {
+                                throw new RuntimeException(
+                                        "Class '" + biFunctionClassInfo.name() + "' must contain a no-args constructor");
+                            }
+                        }
+                        reflectiveClass.produce(
+                                new ReflectiveClassBuildItem(true, false, false, biFunctionType.name().toString()));
+                    }
+                }
             }
         }
         if (!classesNeedingReflectionOnMethods.isEmpty()) {

extensions/resteasy-reactive/quarkus-resteasy-reactive-jackson/deployment/src/test/java/io/quarkus/resteasy/reactive/jackson/deployment/test/SimpleJsonResource.java

@@ -1,7 +1,11 @@
 package io.quarkus.resteasy.reactive.jackson.deployment.test;
 
+import java.lang.reflect.ParameterizedType;
+import java.lang.reflect.Type;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.function.BiFunction;
 
 import javax.validation.Valid;
 import javax.ws.rs.Consumes;
@@ -18,7 +22,11 @@
 
 import com.fasterxml.jackson.annotation.JsonView;
 import com.fasterxml.jackson.core.JsonParseException;
+import com.fasterxml.jackson.core.json.JsonWriteFeature;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.ObjectWriter;
 
+import io.quarkus.resteasy.reactive.jackson.CustomSerialization;
 import io.quarkus.runtime.BlockingOperationControl;
 import io.smallrye.mutiny.Multi;
 
@@ -39,6 +47,13 @@ public Person getPerson() {
         return person;
     }
 
+    @CustomSerialization(UnquotedFieldsPersonBiFunction.class)
+    @GET
+    @Path("custom-serialized-person")
+    public Person getCustomSerializedPerson() {
+        return getPerson();
+    }
+
     @POST
     @Path("/person")
     @Produces(MediaType.APPLICATION_JSON)
@@ -97,6 +112,14 @@ public List<Person> getPeople(List<Person> people) {
         return reversed;
     }
 
+    @CustomSerialization(UnquotedFieldsPersonBiFunction.class)
+    @POST
+    @Path("/custom-serialized-people")
+    @Consumes(MediaType.APPLICATION_JSON)
+    public List<Person> getCustomSerializedPeople(List<Person> people) {
+        return getPeople(people);
+    }
+
     @POST
     @Path("/strings")
     public List<String> strings(List<String> strings) {
@@ -171,6 +194,13 @@ public User userWithPrivateView() {
         return testUser();
     }
 
+    @CustomSerialization(UnquotedFieldsPersonBiFunction.class)
+    @GET
+    @Path("/invalid-use-of-custom-serializer")
+    public User invalidUseOfCustomSerializer() {
+        return testUser();
+    }
+
     private User testUser() {
         User user = new User();
         user.id = 1;
@@ -204,4 +234,24 @@ public Multi<Person> getMulti2() {
     public Multi<Person> getMulti0() {
         return Multi.createFrom().empty();
     }
+
+    public static class UnquotedFieldsPersonBiFunction implements BiFunction<ObjectMapper, Type, ObjectWriter> {
+
+        public static final AtomicInteger count = new AtomicInteger();
+
+        public UnquotedFieldsPersonBiFunction() {
+            count.incrementAndGet();
+        }
+
+        @Override
+        public ObjectWriter apply(ObjectMapper objectMapper, Type type) {
+            if (type instanceof ParameterizedType) {
+                type = ((ParameterizedType) type).getActualTypeArguments()[0];
+            }
+            if (!type.getTypeName().equals(Person.class.getName())) {
+                throw new IllegalArgumentException("Only Person type can be handled");
+            }
+            return objectMapper.writer().without(JsonWriteFeature.QUOTE_FIELD_NAMES);
+        }
+    }
 }

extensions/resteasy-reactive/quarkus-resteasy-reactive-jackson/deployment/src/test/java/io/quarkus/resteasy/reactive/jackson/deployment/test/SimpleJsonTest.java

@@ -2,6 +2,7 @@
 
 import static org.hamcrest.Matchers.containsString;
 import static org.hamcrest.Matchers.not;
+import static org.junit.jupiter.api.Assertions.assertEquals;
 
 import java.util.function.Supplier;
 
@@ -228,4 +229,57 @@ public void testJsonMulti() {
                 .contentType("application/json")
                 .body(Matchers.equalTo("[]"));
     }
+
+    @Test
+    public void testCustomSerialization() {
+        assertEquals(0, SimpleJsonResource.UnquotedFieldsPersonBiFunction.count.intValue());
+
+        // assert that we get a proper response
+        // we can't use json-path to assert because the returned string is not proper json as it does not have quotes around the field names
+        RestAssured.get("/simple/custom-serialized-person")
+                .then()
+                .statusCode(200)
+                .contentType("application/json")
+                .body(containsString("Bob"))
+                .body(containsString("Builder"));
+        // assert that our bi-function was created
+        assertEquals(1, SimpleJsonResource.UnquotedFieldsPersonBiFunction.count.intValue());
+
+        // assert with a list of people
+        RestAssured
+                .with()
+                .body("[{\"first\": \"Bob\", \"last\": \"Builder\"}, {\"first\": \"Bob2\", \"last\": \"Builder2\"}]")
+                .contentType("application/json; charset=utf-8")
+                .post("/simple/custom-serialized-people")
+                .then()
+                .statusCode(200)
+                .contentType("application/json")
+                .body(containsString("Bob"))
+                .body(containsString("Builder"))
+                .body(containsString("Bob2"))
+                .body(containsString("Builder2"));
+        // assert that another instance of our bi-function was created as a different resource method was used
+        assertEquals(2, SimpleJsonResource.UnquotedFieldsPersonBiFunction.count.intValue());
+
+        RestAssured.get("/simple/custom-serialized-person")
+                .then()
+                .statusCode(200)
+                .contentType("application/json");
+        RestAssured
+                .with()
+                .body("[{\"first\": \"Bob\", \"last\": \"Builder\"}, {\"first\": \"Bob2\", \"last\": \"Builder2\"}]")
+                .contentType("application/json; charset=utf-8")
+                .post("/simple/custom-serialized-people")
+                .then()
+                .statusCode(200)
+                .contentType("application/json");
+        // assert that the instances were re-used as we simply invoked methods that should have already created their object writters
+        assertEquals(2, SimpleJsonResource.UnquotedFieldsPersonBiFunction.count.intValue());
+
+        RestAssured.get("/simple/invalid-use-of-custom-serializer")
+                .then()
+                .statusCode(500);
+        // a new instance should have been created
+        assertEquals(3, SimpleJsonResource.UnquotedFieldsPersonBiFunction.count.intValue());
+    }
 }

extensions/resteasy-reactive/quarkus-resteasy-reactive-jackson/runtime/src/main/java/io/quarkus/resteasy/reactive/jackson/CustomSerialization.java

@@ -0,0 +1,40 @@
+package io.quarkus.resteasy.reactive.jackson;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+import java.lang.reflect.Type;
+import java.util.function.BiFunction;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.ObjectWriter;
+
+import io.smallrye.common.annotation.Experimental;
+
+/**
+ * Annotation that can be used on RESTEasy Reactive Resource method to allow users to configure Jackson serialization
+ * for that method only, without affecting the global Jackson configuration.
+ */
+@Experimental(value = "Remains to be determined if this is the best possible API for users to configure per Resource Method Serialization")
+@Retention(RetentionPolicy.RUNTIME)
+@Target({ ElementType.METHOD })
+public @interface CustomSerialization {
+
+    /**
+     * A {@code BiFunction} that converts the global {@code ObjectMapper} and type for which a custom {@code ObjectWriter} is
+     * needed
+     * (this type will be a generic type if the method returns such a generic type) and returns the instance of the custom
+     * {@code ObjectWriter}.
+     *
+     * Quarkus will construct one instance of this {@code BiFunction} for each JAX-RS resource method that is annotated with
+     * {@code CustomSerialization} and once an instance is created it will be cached for subsequent usage by that resource
+     * method.
+     *
+     * The class MUST contain a no-args constructor and it is advisable that it contains no state that is updated outside
+     * of its constructor.
+     * Furthermore, the {@code ObjectMapper} should NEVER be changed any way as it is the global ObjectMapper that is
+     * accessible to the entire Quarkus application.
+     */
+    Class<? extends BiFunction<ObjectMapper, Type, ObjectWriter>> value();
+}

extensions/resteasy-reactive/quarkus-resteasy-reactive-jackson/runtime/src/main/java/io/quarkus/resteasy/reactive/jackson/runtime/serialisers/JacksonMessageBodyWriter.java

@@ -7,6 +7,11 @@
 import java.lang.annotation.Annotation;
 import java.lang.reflect.Method;
 import java.lang.reflect.Type;
+import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
+import java.util.function.BiFunction;
+import java.util.function.Function;
 
 import javax.inject.Inject;
 import javax.ws.rs.WebApplicationException;
@@ -23,20 +28,27 @@
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.fasterxml.jackson.databind.ObjectWriter;
 
+import io.quarkus.resteasy.reactive.jackson.CustomSerialization;
+
 public class JacksonMessageBodyWriter implements ServerMessageBodyWriter<Object> {
 
     private static final String JSON_VIEW_NAME = JsonView.class.getName();
-    private final ObjectWriter writer;
+    private static final String CUSTOM_SERIALIZATION = CustomSerialization.class.getName();
+
+    private final ObjectMapper originalMapper;
+    private final ObjectWriter defaultWriter;
+    private final ConcurrentMap<Method, ObjectWriter> perMethodWriter = new ConcurrentHashMap<>();
 
     @Inject
     public JacksonMessageBodyWriter(ObjectMapper mapper) {
+        this.originalMapper = mapper;
         // we don't want the ObjectWriter to close the stream automatically, as we want to handle closing manually at the proper points
         if (mapper.getFactory().isEnabled(JsonGenerator.Feature.AUTO_CLOSE_TARGET)) {
             JsonFactory jsonFactory = mapper.getFactory().copy();
             jsonFactory.configure(JsonGenerator.Feature.AUTO_CLOSE_TARGET, false);
-            this.writer = mapper.writer().with(jsonFactory);
+            this.defaultWriter = mapper.writer().with(jsonFactory);
         } else {
-            this.writer = mapper.writer();
+            this.defaultWriter = mapper.writer();
         }
     }
 
@@ -61,7 +73,7 @@ public void writeTo(Object o, Class<?> type, Type genericType, Annotation[] anno
                     }
                 }
             }
-            entityStream.write(writer.writeValueAsBytes(o));
+            entityStream.write(defaultWriter.writeValueAsBytes(o));
         }
     }
 
@@ -81,23 +93,69 @@ public void writeResponse(Object o, Type genericType, ServerRequestContext conte
             // First test the names to see if JsonView is used. We do this to avoid doing reflection for the common case
             // where JsonView is not used
             ResteasyReactiveResourceInfo resourceInfo = context.getResteasyReactiveResourceInfo();
-            if ((resourceInfo != null) && resourceInfo.getMethodAnnotationNames().contains(JSON_VIEW_NAME)) {
-                Method method = resourceInfo.getMethod();
-                if (handleJsonView(method.getAnnotation(JsonView.class), o, stream)) {
-                    return;
+            if (resourceInfo != null) {
+                Set<String> methodAnnotationNames = resourceInfo.getMethodAnnotationNames();
+                if (methodAnnotationNames.contains(CUSTOM_SERIALIZATION)) {
+                    Method method = resourceInfo.getMethod();
+                    if (handleCustomSerialization(method, o, genericType, stream)) {
+                        return;
+                    }
+                } else if (methodAnnotationNames.contains(JSON_VIEW_NAME)) {
+                    Method method = resourceInfo.getMethod();
+                    if (handleJsonView(method.getAnnotation(JsonView.class), o, stream)) {
+                        return;
+                    }
                 }
             }
-            writer.writeValue(stream, o);
+            defaultWriter.writeValue(stream, o);
         }
         // we don't use try-with-resources because that results in writing to the http output without the exception mapping coming into play
         stream.close();
     }
 
+    // TODO: this can definitely be made faster if necessary by optimizing the use of the map and also by moving the creation of the
+    //  biFunction to build time
+    private boolean handleCustomSerialization(Method method, Object o, Type genericType, OutputStream stream)
+            throws IOException {
+        CustomSerialization customSerialization = method.getAnnotation(CustomSerialization.class);
+        if ((customSerialization == null)) {
+            return false;
+        }
+        Class<? extends BiFunction<ObjectMapper, Type, ObjectWriter>> biFunctionClass = customSerialization.value();
+        ObjectWriter objectWriter = perMethodWriter.computeIfAbsent(method,
+                new MethodObjectWriterFunction(biFunctionClass, genericType, originalMapper));
+        objectWriter.writeValue(stream, o);
+        return true;
+    }
+
     private boolean handleJsonView(JsonView jsonView, Object o, OutputStream stream) throws IOException {
         if ((jsonView != null) && (jsonView.value().length > 0)) {
-            writer.withView(jsonView.value()[0]).writeValue(stream, o);
+            defaultWriter.withView(jsonView.value()[0]).writeValue(stream, o);
             return true;
         }
         return false;
     }
+
+    private static class MethodObjectWriterFunction implements Function<Method, ObjectWriter> {
+        private final Class<? extends BiFunction<ObjectMapper, Type, ObjectWriter>> clazz;
+        private final Type genericType;
+        private final ObjectMapper originalMapper;
+
+        public MethodObjectWriterFunction(Class<? extends BiFunction<ObjectMapper, Type, ObjectWriter>> clazz, Type genericType,
+                ObjectMapper originalMapper) {
+            this.clazz = clazz;
+            this.genericType = genericType;
+            this.originalMapper = originalMapper;
+        }
+
+        @Override
+        public ObjectWriter apply(Method method) {
+            try {
+                BiFunction<ObjectMapper, Type, ObjectWriter> biFunctionInstance = clazz.getDeclaredConstructor().newInstance();
+                return biFunctionInstance.apply(originalMapper, genericType);
+            } catch (Exception e) {
+                throw new RuntimeException(e);
+            }
+        }
+    }
 }