Configure visibility (#29797)

akka-serialization-jackson/src/main/resources/reference.conf

@@ -126,6 +126,20 @@ akka.serialization.jackson {
   # }
   json-write-features {}
 
+  # Configuration of the JsonFactory Visibility.
+  # See com.fasterxml.jackson.annotation.PropertyAccessor
+  # and com.fasterxml.jackson.annotation.JsonAutoDetect.Visibility
+  # Enum values. For example, to serialize only public fields
+  # overwrite the default values with:
+  #
+  # visibility {
+  #   FIELD = PUBLIC_ONLY
+  # }
+  # Default: all fields (including private and protected) are serialized.
+  visibility {
+    FIELD = ANY
+  }
+
   # Deprecated, use `allowed-class-prefix` instead
   whitelist-class-prefix = []
 

akka-serialization-jackson/src/main/scala/akka/serialization/jackson/JacksonObjectMapperProvider.scala

@@ -179,6 +179,25 @@ object JacksonObjectMapperProvider extends ExtensionId[JacksonObjectMapperProvid
     }
   }
 
+  private def configureObjectVisibility(
+      bindingName: String,
+      objectMapper: ObjectMapper,
+      objectMapperFactory: JacksonObjectMapperFactory,
+      config: Config): Unit = {
+
+    val configuredVisibility: immutable.Seq[(PropertyAccessor, JsonAutoDetect.Visibility)] =
+      configPairs(config, "visibility").map {
+        case (property, visibility) =>
+          PropertyAccessor.valueOf(property) -> JsonAutoDetect.Visibility.valueOf(visibility)
+      }
+    val visibility =
+      objectMapperFactory.overrideConfiguredVisibility(bindingName, configuredVisibility)
+    visibility.foreach {
+      case (property, visibility) => objectMapper.setVisibility(property, visibility)
+    }
+
+  }
+
   private def configureObjectMapperModules(
       bindingName: String,
       objectMapper: ObjectMapper,
@@ -244,8 +263,9 @@ object JacksonObjectMapperProvider extends ExtensionId[JacksonObjectMapperProvid
 
     configureObjectMapperFeatures(bindingName, mapper, objectMapperFactory, config)
     configureObjectMapperModules(bindingName, mapper, objectMapperFactory, config, dynamicAccess, log)
+    configureObjectVisibility(bindingName, mapper, objectMapperFactory, config)
 
-    mapper.setVisibility(PropertyAccessor.FIELD, JsonAutoDetect.Visibility.ANY)
+    mapper
   }
 
   private def isModuleEnabled(fqcn: String, dynamicAccess: DynamicAccess): Boolean =
@@ -264,6 +284,12 @@ object JacksonObjectMapperProvider extends ExtensionId[JacksonObjectMapperProvid
     val cfg = config.getConfig(section)
     cfg.root.keySet().asScala.map(key => key -> cfg.getBoolean(key)).toList
   }
+
+  private def configPairs(config: Config, section: String): immutable.Seq[(String, String)] = {
+    import akka.util.ccompat.JavaConverters._
+    val cfg = config.getConfig(section)
+    cfg.root.keySet().asScala.map(key => key -> cfg.getString(key)).toList
+  }
 }
 
 /**
@@ -534,4 +560,20 @@ class JacksonObjectMapperFactory {
       @unused bindingName: String,
       configuredFeatures: immutable.Seq[(JsonWriteFeature, Boolean)]): immutable.Seq[(JsonWriteFeature, Boolean)] =
     configuredFeatures
+
+  /**
+   * Visibility settings used to configure the `JsonFactoryBuilder` that, if provided, will later be used to create
+   * an `ObjectMapper`. These settings can be amended programmatically by overriding this method and return the values
+   * that are to be applied to the `JsonFactoryBuilder`.
+   *
+   * @param bindingName bindingName name of this `ObjectMapper`
+   * @param configuredFeatures the list of `PropertyAccessor`/`JsonAutoDetect.Visibility` that were configured in
+   *                           `akka.serialization.jackson.visibility`
+   */
+  def overrideConfiguredVisibility(
+      @unused bindingName: String,
+      configuredFeatures: immutable.Seq[(PropertyAccessor, JsonAutoDetect.Visibility)])
+      : immutable.Seq[(PropertyAccessor, JsonAutoDetect.Visibility)] =
+    configuredFeatures
+
 }

akka-serialization-jackson/src/test/java/akka/serialization/jackson/JavaTestMessages.java

@@ -528,4 +528,15 @@ public interface JavaTestMessages {
       return name != null ? name.hashCode() : 0;
     }
   }
+
+  // A class with non-public fields
+  final class ClassWithVisibility {
+    public final String publicField = "1234";
+    final String defaultField = "abcd";
+    protected final String protectedField = "vwxyz";
+    private final String privateField = "ABCD";
+
+    @JsonCreator
+    public ClassWithVisibility() {}
+  }
 }

akka-serialization-jackson/src/test/scala/akka/serialization/jackson/JacksonSerializerSpec.scala

@@ -411,6 +411,46 @@ class JacksonJsonSerializerSpec extends JacksonSerializerSpec("jackson-json") {
     "be possible to create custom ObjectMapper" in {
       pending
     }
+
+    "be possible to tune the visibility at ObjectMapper level (FIELD, PUBLIC_ONLY)" in {
+      withSystem("""
+        akka.actor {
+          serialization-bindings {
+            "akka.serialization.jackson.JavaTestMessages$ClassWithVisibility" = jackson-json
+          }
+        }
+        akka.serialization.jackson.visibility {
+          FIELD = PUBLIC_ONLY
+        }
+        """) { sys =>
+        val msg = new ClassWithVisibility();
+        val json = serializeToJsonString(msg, sys)
+        val expected = """{"publicField":"1234"}"""
+        json should ===(expected)
+      }
+    }
+
+    // This test ensures the default behavior in Akka 2.6 series
+    // (that is "FIELD = ANY") stays consistent
+    "be possible to tune the visibility at ObjectMapper level (Akka default)" in {
+      withSystem("""
+        akka.actor {
+          serialization-bindings {
+            "akka.serialization.jackson.JavaTestMessages$ClassWithVisibility" = jackson-json
+          }
+        }
+        akka.serialization.jackson.visibility {
+          ## No overrides
+        }
+        """) { sys =>
+        val msg = new ClassWithVisibility();
+        val json = serializeToJsonString(msg, sys)
+        val expected =
+          """{"publicField":"1234","defaultField":"abcd","protectedField":"vwxyz","privateField":"ABCD"}""".stripMargin
+        json should ===(expected)
+      }
+    }
+
   }
 
   "JacksonJsonSerializer with Scala message classes" must {