Merge pull request #353 from avaje/feature/npe-custom-serializer

Fix NPE when custom JsonAdapter (not nullSafe()) is registered via Supplier

Author: SentryMan

blackbox-test/src/main/java/org/example/other/custom/serializer/CustomExample2.java

@@ -0,0 +1,11 @@
+package org.example.other.custom.serializer;
+
+import io.avaje.jsonb.Json;
+
+import java.math.BigDecimal;
+
+@Json
+public record CustomExample2(
+    @Json.Serializer(MoneySerializer2.class)
+    BigDecimal amountOwed,
+    BigDecimal somethingElse) {}

blackbox-test/src/main/java/org/example/other/custom/serializer/MoneySerializer.java

@@ -12,6 +12,7 @@
 @CustomAdapter(global = false)
 public class MoneySerializer implements JsonAdapter<BigDecimal> {
 
+  /** Constructor takes Jsonb, registered via AdapterBuilder */
   public MoneySerializer(Jsonb jsonb) {}
 
   @Override

blackbox-test/src/main/java/org/example/other/custom/serializer/MoneySerializer2.java

@@ -0,0 +1,26 @@
+package org.example.other.custom.serializer;
+
+import io.avaje.json.JsonAdapter;
+import io.avaje.json.JsonReader;
+import io.avaje.json.JsonWriter;
+import io.avaje.jsonb.CustomAdapter;
+
+import java.math.BigDecimal;
+import java.math.RoundingMode;
+
+@CustomAdapter(global = false)
+public class MoneySerializer2 implements JsonAdapter<BigDecimal> {
+
+  /**  Default constructor -> registered via {@code Supplier<JsonAdapter>} */
+  public MoneySerializer2() { }
+
+  @Override
+  public BigDecimal fromJson(JsonReader reader) {
+    return reader.readDecimal().setScale(2, RoundingMode.DOWN);
+  }
+
+  @Override
+  public void toJson(JsonWriter writer, BigDecimal value) {
+    writer.value(value.setScale(2, RoundingMode.DOWN));
+  }
+}

blackbox-test/src/test/java/org/example/other/custom/serializer/SelectiveCustomSerializerSupplierTest.java

@@ -0,0 +1,43 @@
+package org.example.other.custom.serializer;
+
+import io.avaje.jsonb.JsonType;
+import io.avaje.jsonb.Jsonb;
+import org.junit.jupiter.api.Test;
+
+import java.math.BigDecimal;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/** Uses MoneySerializer2 which is registered via Supplier */
+class SelectiveCustomSerializerSupplierTest {
+
+  Jsonb jsonb = Jsonb.builder().build();
+  JsonType<CustomExample2> jsonType = jsonb.type(CustomExample2.class);
+
+  @Test
+  void toFromJson() {
+    final var bean = new CustomExample2(new BigDecimal("100.95630"), new BigDecimal("100.95630"));
+
+    final String asJson = jsonType.toJson(bean);
+    assertThat(asJson).isEqualTo("{\"amountOwed\":100.95,\"somethingElse\":100.95630}");
+
+    final var fromJson = jsonType.fromJson(asJson);
+    assertThat(fromJson.amountOwed()).isEqualTo(new BigDecimal("100.95"));
+    assertThat(fromJson.somethingElse()).isEqualTo(new BigDecimal("100.95630"));
+    assertThat(fromJson).isNotEqualTo(bean);
+  }
+
+  @Test
+  void toFromJson_with_null() {
+    final var bean = new CustomExample2(null, null);
+
+    final String asJson = jsonType.toJson(bean);
+    assertThat(asJson).isEqualTo("{}");
+
+    final var fromJson = jsonType.fromJson(asJson);
+    assertThat(fromJson.amountOwed()).isNull();
+    assertThat(fromJson.somethingElse()).isNull();
+    assertThat(fromJson).isEqualTo(bean);
+  }
+
+}

blackbox-test/src/test/java/org/example/other/custom/serializer/CustomExampleTest.java renamed to blackbox-test/src/test/java/org/example/other/custom/serializer/SelectiveCustomSerializerTest.java

@@ -9,7 +9,8 @@
 import io.avaje.jsonb.JsonType;
 import io.avaje.jsonb.Jsonb;
 
-class TestSelectiveSerializer {
+/** Uses MoneySerializer which is registered via AdapterBuilder */
+class SelectiveCustomSerializerTest {
 
   Jsonb jsonb = Jsonb.builder().build();
   JsonType<CustomExample> jsonType = jsonb.type(CustomExample.class);
@@ -26,4 +27,18 @@ void toFromJson() {
     assertThat(fromJson.somethingElse()).isEqualTo(new BigDecimal("100.95630"));
     assertThat(fromJson).isNotEqualTo(bean);
   }
+
+  @Test
+  void toFromJson_with_null() {
+    final var bean = new CustomExample(null, null);
+
+    final String asJson = jsonType.toJson(bean);
+    assertThat(asJson).isEqualTo("{}");
+
+    final var fromJson = jsonType.fromJson(asJson);
+    assertThat(fromJson.amountOwed()).isNull();
+    assertThat(fromJson.somethingElse()).isNull();
+    assertThat(fromJson).isEqualTo(bean);
+  }
+
 }

jsonb/src/main/java/io/avaje/jsonb/core/DJsonb.java

@@ -346,7 +346,7 @@ static <T> AdapterFactory newAdapterFactory(Type type, JsonAdapter<T> jsonAdapte
     static <T> AdapterFactory newAdapterFactory(Type type, Supplier<JsonAdapter<T>> jsonAdapter) {
       requireNonNull(type);
       requireNonNull(jsonAdapter);
-      return (targetType, jsonb) -> simpleMatch(type, targetType) ? jsonAdapter.get() : null;
+      return (targetType, jsonb) -> simpleMatch(type, targetType) ? jsonAdapter.get().nullSafe() : null;
     }
 
     static AdapterFactory newAdapterFactory(Type type, AdapterBuilder builder) {