#25 - Detect "value types" that should have their own custom JsonAdapter

Author: rbygrave

blackbox-test/src/main/java/org/example/customer/customtype/CustomTypeComponent.java

@@ -0,0 +1,31 @@
+package org.example.customer.customtype;
+
+
+import io.avaje.jsonb.*;
+
+/**
+ * Register via service loading.
+ */
+public class CustomTypeComponent implements JsonbComponent {
+
+  @Override
+  public void register(Jsonb.Builder builder) {
+    builder.add(MyCustomScalarType.class, new CustomTypeAdapterWithStar().nullSafe());
+  }
+
+  static class CustomTypeAdapterWithStar extends JsonAdapter<MyCustomScalarType> {
+
+    @Override
+    public void toJson(JsonWriter writer, MyCustomScalarType value) {
+      writer.value("*** " + value.toString());
+    }
+
+    @Override
+    public MyCustomScalarType fromJson(JsonReader reader) {
+      String encoded = reader.readString();
+      return MyCustomScalarType.of(encoded.substring(4)); // trim those stars
+    }
+  }
+
+}
+

blackbox-test/src/main/java/org/example/customer/customtype/MyCustomScalarType.java

@@ -0,0 +1,40 @@
+package org.example.customer.customtype;
+
+import java.util.Arrays;
+import java.util.Base64;
+
+public final class MyCustomScalarType {
+
+  private final byte[] data;
+
+  public MyCustomScalarType(byte[] data) {
+    this.data = data;
+  }
+
+  public static MyCustomScalarType of(String encoded) {
+    byte[] bytes = Base64.getDecoder().decode(encoded);
+    return new MyCustomScalarType(bytes);
+  }
+
+  public static MyCustomScalarType of(byte[] raw) {
+    return new MyCustomScalarType(raw);
+  }
+
+  @Override
+  public String toString() {
+    return Base64.getEncoder().encodeToString(data);
+  }
+
+  @Override
+  public boolean equals(Object o) {
+    if (this == o) return true;
+    if (o == null || getClass() != o.getClass()) return false;
+    MyCustomScalarType that = (MyCustomScalarType) o;
+    return Arrays.equals(data, that.data);
+  }
+
+  @Override
+  public int hashCode() {
+    return Arrays.hashCode(data);
+  }
+}

blackbox-test/src/main/java/org/example/customer/customtype/MyWrapper.java

@@ -0,0 +1,7 @@
+package org.example.customer.customtype;
+
+import io.avaje.jsonb.Json;
+
+@Json
+public record MyWrapper(int id, String base, MyCustomScalarType custom) {
+}

blackbox-test/src/main/resources/META-INF/services/io.avaje.jsonb.JsonbComponent

@@ -0,0 +1 @@
+org.example.customer.customtype.CustomTypeComponent

blackbox-test/src/test/java/org/example/customer/customtype/CustomScalarTypeTest.java

@@ -0,0 +1,67 @@
+package org.example.customer.customtype;
+
+import io.avaje.jsonb.JsonAdapter;
+import io.avaje.jsonb.JsonReader;
+import io.avaje.jsonb.JsonWriter;
+import io.avaje.jsonb.Jsonb;
+import org.junit.jupiter.api.Test;
+
+import java.nio.charset.StandardCharsets;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class CustomScalarTypeTest {
+
+  /**
+   * Using the {@link CustomTypeComponent} which is service loaded.
+   */
+  @Test
+  void toJson_fromJson_usingComponent() {
+    Jsonb jsonb = Jsonb.builder()
+      // service loading finds and loads CustomTypeComponent
+      .build();
+
+    MyWrapper wrapper = new MyWrapper(42, "hello", new MyCustomScalarType("hello".getBytes(StandardCharsets.UTF_8)));
+
+    String asJson = jsonb.toJson(wrapper);
+    assertThat(asJson).isEqualTo("{\"id\":42,\"base\":\"hello\",\"custom\":\"*** aGVsbG8=\"}");
+
+    MyWrapper wrapper1 = jsonb.type(MyWrapper.class).fromJson(asJson);
+
+    assertThat(wrapper1).isEqualTo(wrapper);
+    assertThat(wrapper1.custom()).isEqualTo(wrapper.custom());
+  }
+
+  @Test
+  void toJson_fromJson() {
+    Jsonb jsonb = Jsonb.builder()
+      // explicitly register the CustomTypeAdapter for our value type
+      .add(MyCustomScalarType.class, new CustomTypeAdapter().nullSafe())
+      .build();
+
+    MyWrapper wrapper = new MyWrapper(42, "hello", new MyCustomScalarType("hello".getBytes(StandardCharsets.UTF_8)));
+
+    String asJson = jsonb.toJson(wrapper);
+    assertThat(asJson).isEqualTo("{\"id\":42,\"base\":\"hello\",\"custom\":\"aGVsbG8=\"}");
+
+    MyWrapper wrapper1 = jsonb.type(MyWrapper.class).fromJson(asJson);
+
+    assertThat(wrapper1).isEqualTo(wrapper);
+    assertThat(wrapper1.custom()).isEqualTo(wrapper.custom());
+  }
+
+  static class CustomTypeAdapter extends JsonAdapter<MyCustomScalarType> {
+
+    @Override
+    public void toJson(JsonWriter writer, MyCustomScalarType value) {
+      writer.value(value.toString());
+    }
+
+    @Override
+    public MyCustomScalarType fromJson(JsonReader reader) {
+      String encoded = reader.readString();
+      return MyCustomScalarType.of(encoded);
+    }
+  }
+
+}

jsonb-generator/src/main/java/io/avaje/jsonb/generator/BeanReader.java

@@ -1,5 +1,7 @@
 package io.avaje.jsonb.generator;
 
+import io.avaje.jsonb.Json;
+
 import javax.lang.model.element.Element;
 import javax.lang.model.element.TypeElement;
 import java.util.HashSet;
@@ -20,6 +22,7 @@ class BeanReader {
   private final boolean hasSubTypes;
   private final TypeReader typeReader;
   private final String typeProperty;
+  private final boolean nonAccessibleField;
   private FieldReader unmappedField;
   private boolean hasRaw;
 
@@ -33,6 +36,7 @@ class BeanReader {
 
     this.typeReader = new TypeReader(beanType, context, namingConvention);
     typeReader.process();
+    this.nonAccessibleField = typeReader.nonAccessibleField();
     this.hasSubTypes = typeReader.hasSubTypes();
     this.allFields = typeReader.allFields();
     this.constructor = typeReader.constructor();
@@ -59,6 +63,14 @@ boolean hasSubtypes() {
     return hasSubTypes;
   }
 
+  boolean nonAccessibleField() {
+    return nonAccessibleField;
+  }
+
+  boolean hasJsonAnnotation() {
+    return beanType.getAnnotation(Json.class) != null;
+  }
+
   void read() {
     for (FieldReader field : allFields) {
       field.addImports(importTypes);

jsonb-generator/src/main/java/io/avaje/jsonb/generator/Processor.java

@@ -160,6 +160,12 @@ private void writeAdapters(Set<? extends Element> beans) {
   private void writeAdapterForType(TypeElement typeElement) {
     BeanReader beanReader = new BeanReader(typeElement, context);
     beanReader.read();
+    if (beanReader.nonAccessibleField()) {
+      if (beanReader.hasJsonAnnotation()) {
+        context.logError("Error JsonAdapter due to nonAccessibleField for %s ", beanReader);
+      }
+      return;
+    }
     try {
       SimpleAdapterWriter beanWriter = new SimpleAdapterWriter(beanReader, context);
       metaData.add(beanWriter.fullName());

jsonb-generator/src/main/java/io/avaje/jsonb/generator/TypeReader.java

@@ -1,5 +1,7 @@
 package io.avaje.jsonb.generator;
 
+import io.avaje.jsonb.Json;
+
 import javax.lang.model.element.*;
 import java.util.*;
 
@@ -23,15 +25,18 @@ class TypeReader {
   private final TypeElement baseType;
   private final ProcessingContext context;
   private final NamingConvention namingConvention;
+  private final boolean hasJsonAnnotation;
   private MethodReader constructor;
   private boolean defaultPublicConstructor;
   private final Map<String, MethodReader.MethodParam> constructorParamMap = new LinkedHashMap<>();
   private TypeSubTypeMeta currentSubType;
+  private boolean nonAccessibleField;
 
   TypeReader(TypeElement baseType, ProcessingContext context, NamingConvention namingConvention) {
     this.baseType = baseType;
     this.context = context;
     this.namingConvention = namingConvention;
+    this.hasJsonAnnotation = baseType.getAnnotation(Json.class) != null;
     this.subTypes = new TypeSubTypeReader(baseType, context);
   }
 
@@ -192,7 +197,12 @@ private void matchFieldToGetter(FieldReader field) {
     if (!matchFieldToGetter2(field, false)) {
       if (!matchFieldToGetter2(field, true)) {
         if (!field.isPublicField()) {
-          context.logError("Non public field " + baseType + " " + field.fieldName() + " with no matching getter ?");
+          nonAccessibleField = true;
+          if (hasJsonAnnotation) {
+            context.logError("Non accessible field " + baseType + " " + field.fieldName() + " with no matching getter?");
+          } else {
+            context.logDebug("Non accessible field " + baseType + " " + field.fieldName());
+          }
         }
       }
     }
@@ -238,6 +248,10 @@ private String isGetterName(String name) {
     return "is" + Util.initCap(name);
   }
 
+  boolean nonAccessibleField() {
+    return nonAccessibleField;
+  }
+
   List<FieldReader> allFields() {
     return allFields;
   }

jsonb-jakarta/src/test/java/org/example/MyCustomerTest.java

@@ -15,7 +15,7 @@ class MyCustomerTest {
   @Test
   void toJson_fromJson() {
 
-    Jsonb jsonb = Jsonb.newBuilder().build();
+    Jsonb jsonb = Jsonb.builder().build();
 
     MyCustomer myCustomer = new MyCustomer(42, "rob", "foo");
     JsonType<MyCustomer> type = jsonb.type(MyCustomer.class);
@@ -36,7 +36,7 @@ void toJson_fromJson() {
   @Test
   void list_toJson_fromJson() {
 
-    Jsonb jsonb = Jsonb.newBuilder().adapter(new JakartaIOAdapter()).build();
+    Jsonb jsonb = Jsonb.builder().adapter(new JakartaIOAdapter()).build();
 
     List<MyCustomer> customers = new ArrayList<>();
     customers.add(new MyCustomer(42, "rob", "foo"));

jsonb/src/main/java/io/avaje/jsonb/Jsonb.java

@@ -396,7 +396,7 @@ interface Builder {
     /**
      * Add a Component which can provide multiple JsonAdapters and or configuration.
      */
-    Builder add(Jsonb.Component component);
+    Builder add(JsonbComponent component);
 
     /**
      * Add a JsonAdapter.Factory which provides JsonAdapters to use.
@@ -425,7 +425,7 @@ interface AdapterBuilder {
    * Components register JsonAdapters Jsonb.Builder
    */
   @FunctionalInterface
-  interface Component {
+  interface Component extends JsonbComponent {
 
     /**
      * Register JsonAdapters with the Builder.