parallel structure for JSonSerializer/DeserializerWithAccessFilter

src/main/java/org/hostsharing/hsadminng/service/accessfilter/JSonDeserializerWithAccessFilter.java

@@ -20,9 +20,10 @@ public class JSonDeserializerWithAccessFilter<T> {
 
     public JSonDeserializerWithAccessFilter(final JsonParser jsonParser, final DeserializationContext deserializationContext, Class<T> dtoClass) {
         this.treeNode = unchecked(() -> jsonParser.getCodec().readTree(jsonParser));
-        this.dto = unchecked(() -> dtoClass.newInstance());
+        this.dto = unchecked(dtoClass::newInstance);
     }
 
+    // Jackson deserializes from the JsonParser, thus no input parameter needed.
     public T deserialize() {
         treeNode.fieldNames().forEachRemaining(fieldName -> {
             try {

src/main/java/org/hostsharing/hsadminng/service/accessfilter/JSonSerializerWithAccessFilter.java

@@ -13,21 +13,26 @@ import java.lang.reflect.Field;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 
-@JsonComponent
+public class JSonSerializerWithAccessFilter <T> {
-public class JSonSerializerWithAccessFilter extends JsonSerializer<Object> {
+    private final JsonGenerator jsonGenerator;
+    private final SerializerProvider serializerProvider;
+    private final T dto;
 
-    @Override
+    public JSonSerializerWithAccessFilter(final JsonGenerator jsonGenerator,
-    public void serialize(final Object dto, final JsonGenerator jsonGenerator,
+                                          final SerializerProvider serializerProvider,
-                          final SerializerProvider serializerProvider) throws IOException {
+                                          final T dto) {
+        this.jsonGenerator = jsonGenerator;
+        this.serializerProvider = serializerProvider;
+        this.dto = dto;
+    }
+
+    // Jackson serializes into the JsonGenerator, thus no return value needed.
+    public void serialize() throws IOException {
 
-        // TODO: Move the implementation to an (if necessary, inner) class, or maybe better
-        //  expose just the inner implementation from an explicit @JsonCompontent
-        //  as it's necessary for the deserializers anyway.
         jsonGenerator.writeStartObject();
         for (Field prop : dto.getClass().getDeclaredFields()) {
             toJSon(dto, jsonGenerator, prop);
         }
-
         jsonGenerator.writeEndObject();
     }
 
@@ -35,9 +40,10 @@ public class JSonSerializerWithAccessFilter extends JsonSerializer<Object> {
         if (getLoginUserRole().isAllowedToRead(prop)) {
             final String fieldName = prop.getName();
             // TODO: maybe replace by serializerProvider.defaultSerialize...()?
-            //  But that's difficult for parallel structure with the deserializer, where the API is ugly.
+            //  But that makes it difficult for parallel structure with the deserializer (clumsy API).
             //  Alternatively extract the supported types to subclasses of some abstract class and
             //  here as well as in the deserializer just access the matching implementation through a map.
+            //  Or even completely switch from Jackson to GSON?
             if (Integer.class.isAssignableFrom(prop.getType()) || int.class.isAssignableFrom(prop.getType())) {
                 jsonGenerator.writeNumberField(fieldName, (int) get(dto, prop));
             } else if (Long.class.isAssignableFrom(prop.getType()) || long.class.isAssignableFrom(prop.getType())) {

src/main/java/org/hostsharing/hsadminng/service/dto/CustomerDTO.java

@@ -1,13 +1,17 @@
 package org.hostsharing.hsadminng.service.dto;
 
+import com.fasterxml.jackson.core.JsonGenerator;
 import com.fasterxml.jackson.core.JsonParser;
 import com.fasterxml.jackson.core.TreeNode;
 import com.fasterxml.jackson.databind.DeserializationContext;
 import com.fasterxml.jackson.databind.JsonDeserializer;
+import com.fasterxml.jackson.databind.JsonSerializer;
+import com.fasterxml.jackson.databind.SerializerProvider;
 import com.fasterxml.jackson.databind.node.IntNode;
 import com.fasterxml.jackson.databind.node.TextNode;
 import org.hostsharing.hsadminng.service.accessfilter.AccessFor;
 import org.hostsharing.hsadminng.service.accessfilter.JSonDeserializerWithAccessFilter;
+import org.hostsharing.hsadminng.service.accessfilter.JSonSerializerWithAccessFilter;
 import org.hostsharing.hsadminng.service.accessfilter.Role;
 import org.springframework.boot.jackson.JsonComponent;
 
@@ -171,13 +175,26 @@ public class CustomerDTO implements Serializable {
     }
 
     @JsonComponent
-    public static class UserJsonDeserializer extends JsonDeserializer<CustomerDTO> {
+    public static class CustomerJsonSerializer extends JsonSerializer<CustomerDTO> {
+
+        @Override
+        public void serialize(final CustomerDTO customerDTO, final JsonGenerator jsonGenerator,
+                              final SerializerProvider serializerProvider) throws IOException {
+
+           new JSonSerializerWithAccessFilter<>(jsonGenerator, serializerProvider, customerDTO).serialize();
+        }
+    }
+
+
+
+    @JsonComponent
+    public static class CustomerJsonDeserializer extends JsonDeserializer<CustomerDTO> {
 
         @Override
         public CustomerDTO deserialize(final JsonParser jsonParser,
                                        final DeserializationContext deserializationContext) {
 
-           return new JSonDeserializerWithAccessFilter<>(jsonParser, deserializationContext, CustomerDTO.class).deserialize();
+            return new JSonDeserializerWithAccessFilter<>(jsonParser, deserializationContext, CustomerDTO.class).deserialize();
         }
     }
 }

src/test/java/org/hostsharing/hsadminng/service/accessfilter/JSonSerializerWithAccessFilterUnitTest.java

@@ -37,7 +37,7 @@ public class JSonSerializerWithAccessFilterUnitTest {
     @Test
     public void shouldSerializeStringField() throws IOException {
         // when
-        new JSonSerializerWithAccessFilter().serialize(givenDTO, jsonGenerator, null);
+        new JSonSerializerWithAccessFilter<>(jsonGenerator, null, givenDTO).serialize();
 
         // then
         verify(jsonGenerator).writeStringField("openStringField", givenDTO.openStringField);
@@ -50,10 +50,10 @@ public class JSonSerializerWithAccessFilterUnitTest {
         givenLoginUserWithRole(Role.FINANCIAL_CONTACT);
 
         // when
-        new JSonSerializerWithAccessFilter().serialize(givenDTO, jsonGenerator, null);
+        new JSonSerializerWithAccessFilter<>(jsonGenerator, null, givenDTO).serialize();
 
         // then
-       verify(jsonGenerator).writeStringField("restrictedField", givenDTO.restrictedField);
+        verify(jsonGenerator).writeStringField("restrictedField", givenDTO.restrictedField);
     }
 
     @Test
@@ -63,25 +63,26 @@ public class JSonSerializerWithAccessFilterUnitTest {
         givenLoginUserWithRole(Role.ANY_CUSTOMER_USER);
 
         // when
-        new JSonSerializerWithAccessFilter().serialize(givenDTO, jsonGenerator, null);
+        new JSonSerializerWithAccessFilter<>(jsonGenerator, null, givenDTO).serialize();
 
         // then
         verify(jsonGenerator, never()).writeStringField("restrictedField", givenDTO.restrictedField);
     }
 
     @Test
-    public void shouldThrowExceptionForUnimplementedFieldType() throws IOException {
+    public void shouldThrowExceptionForUnimplementedFieldType() {
 
         // given
-        class Arbitrary {}
+        class Arbitrary {
+        }
         class GivenDtoWithUnimplementedFieldType {
             @AccessFor(read = Role.ANYBODY)
             Arbitrary fieldWithUnimplementedType;
         }
-        final GivenDtoWithUnimplementedFieldType givenDto = new GivenDtoWithUnimplementedFieldType();
+        final GivenDtoWithUnimplementedFieldType givenDtoWithUnimplementedFieldType = new GivenDtoWithUnimplementedFieldType();
 
         // when
-        Throwable actual = catchThrowable(() -> new JSonSerializerWithAccessFilter().serialize(givenDto, jsonGenerator, null));
+        Throwable actual = catchThrowable(() -> new JSonSerializerWithAccessFilter<>(jsonGenerator, null, givenDtoWithUnimplementedFieldType).serialize());
 
         // then
         assertThat(actual).isInstanceOf(NotImplementedException.class);