refactor to use BeanDeserializerBase, DelegatingDeserializer

Author: goekay

ocpp-jaxb/src/main/java/de/rwth/idsg/ocpp/jaxb/validation/BeanDeserializerModifierWithValidation.java

@@ -5,9 +5,8 @@
 import tools.jackson.databind.DeserializationConfig;
 import tools.jackson.databind.ValueDeserializer;
 import tools.jackson.databind.deser.ValueDeserializerModifier;
-import tools.jackson.databind.deser.bean.BeanDeserializer;
+import tools.jackson.databind.deser.bean.BeanDeserializerBase;
 
-import jakarta.validation.Validation;
 import jakarta.validation.Validator;
 
 /**
@@ -22,8 +21,8 @@ public class BeanDeserializerModifierWithValidation extends ValueDeserializerMod
     public ValueDeserializer<?> modifyDeserializer(DeserializationConfig config,
                                                    Supplier beanDescRef,
                                                    ValueDeserializer<?> deserializer) {
-        if (deserializer instanceof BeanDeserializer) {
-            return new BeanDeserializerWithValidation((BeanDeserializer) deserializer, validator);
+        if (deserializer instanceof BeanDeserializerBase) {
+            return new BeanDeserializerWithValidation((BeanDeserializerBase) deserializer, validator);
         }
 
         return deserializer;

ocpp-jaxb/src/main/java/de/rwth/idsg/ocpp/jaxb/validation/BeanDeserializerWithValidation.java

@@ -3,32 +3,46 @@
 import tools.jackson.core.JacksonException;
 import tools.jackson.core.JsonParser;
 import tools.jackson.databind.DeserializationContext;
-import tools.jackson.databind.deser.bean.BeanDeserializer;
+import tools.jackson.databind.ValueDeserializer;
+import tools.jackson.databind.deser.bean.BeanDeserializerBase;
+import tools.jackson.databind.deser.std.DelegatingDeserializer;
 
 import jakarta.validation.ConstraintViolationException;
 import jakarta.validation.Validator;
 
 /**
  * https://www.baeldung.com/java-object-validation-deserialization
  */
-public class BeanDeserializerWithValidation extends BeanDeserializer {
+public class BeanDeserializerWithValidation extends DelegatingDeserializer {
 
-    private final Validator validator;
-
-    public BeanDeserializerWithValidation(BeanDeserializer src, Validator validator) {
-        super(src);
-        this.validator = validator;
+    public BeanDeserializerWithValidation(BeanDeserializerBase d, Validator validator) {
+        super(create(d, validator));
     }
 
     @Override
-    public Object deserialize(JsonParser p, DeserializationContext ctxt) throws JacksonException {
-        var instance = super.deserialize(p, ctxt);
+    protected ValueDeserializer<?> newDelegatingInstance(ValueDeserializer<?> newDelegatee) {
+        return newDelegatee;
+    }
+
+    private static ValueDeserializer<?> create(ValueDeserializer<?> delegate, Validator validator) {
+        return new ValueDeserializer<>() {
+
+            @Override
+            public Class<?> handledType() {
+                return delegate.handledType(); // otherwise NPE in constructor of DelegatingDeserializer
+            }
+
+            @Override
+            public Object deserialize(JsonParser p, DeserializationContext ctxt) throws JacksonException {
+                var instance = delegate.deserialize(p, ctxt);
 
-        var violations = validator.validate(instance);
-        if (!violations.isEmpty()) {
-            throw new ConstraintViolationException(violations);
-        }
+                var violations = validator.validate(instance);
+                if (!violations.isEmpty()) {
+                    throw new ConstraintViolationException(violations);
+                }
 
-        return instance;
+                return instance;
+            }
+        };
     }
 }