diff --git a/release-notes/VERSION-2.x b/release-notes/VERSION-2.x
index 7b459e08..05147890 100644
--- a/release-notes/VERSION-2.x
+++ b/release-notes/VERSION-2.x
@@ -17,6 +17,8 @@ NOTE: Jackson 3.x components rely on 2.x annotations; there are no separate
2.22 (not yet released)
#339: Add `OptBoolean` valued property "order" in `@JsonIncludeProperties`
+#342: Add `@JsonTypeInfo.writeTypeIdForDefaultImpl` to allow skipping
+ writing of type id for values of default type
2.21 (18-Jan-2026)
diff --git a/src/main/java/com/fasterxml/jackson/annotation/JsonTypeInfo.java b/src/main/java/com/fasterxml/jackson/annotation/JsonTypeInfo.java
index cdb9167d..0f7a2716 100644
--- a/src/main/java/com/fasterxml/jackson/annotation/JsonTypeInfo.java
+++ b/src/main/java/com/fasterxml/jackson/annotation/JsonTypeInfo.java
@@ -67,9 +67,9 @@
public @interface JsonTypeInfo
{
/*
- /**********************************************************
+ /**********************************************************************
/* Value enumerations used for properties
- /**********************************************************
+ /**********************************************************************
*/
/**
@@ -256,9 +256,9 @@ public enum As {
}
/*
- /**********************************************************
+ /**********************************************************************
/* Annotation properties
- /**********************************************************
+ /**********************************************************************
*/
/**
@@ -339,23 +339,6 @@ public enum As {
*/
public boolean visible() default false;
- /*
- /**********************************************************
- /* Helper classes
- /**********************************************************
- */
-
- /**
- * This marker class that is only to be used with defaultImpl
- * annotation property, to indicate that there is no default implementation
- * specified.
- *
- * @deprecated Since 2.5, use any Annotation type (such as {@link JsonTypeInfo}),
- * if such behavior is needed; this is rarely necessary.
- */
- @Deprecated // since 2.5
- public abstract static class None {}
-
/**
* Specifies whether the type ID should be strictly required during polymorphic
* deserialization of its subtypes.
@@ -374,6 +357,44 @@ public abstract static class None {}
*/
public OptBoolean requireTypeIdForSubtypes() default OptBoolean.DEFAULT;
+ /**
+ * Property that defines whether serialization of type id should be done
+ * when the runtime type of the value is the same as {@link #defaultImpl()}.
+ * Skipping write can be useful since during deserialization, if no type id is present,
+ * {@code defaultImpl} is used as the fallback type -- so the type id is redundant
+ * for that type.
+ *
+ * When disabled ({@link OptBoolean#FALSE}), the type id will NOT be written
+ * if the actual runtime class of the value exactly matches {@code defaultImpl}.
+ * Subclasses of {@code defaultImpl} will still have their type id written.
+ *
+ * NOTE: support for this feature is only added in Jackson 3.x, specifically
+ * 3.2. It is not supported by Jackson 2.x.
+ *
+ * Default value is {@link OptBoolean#DEFAULT} (which means {@code TRUE}),
+ * preserving backwards-compatible behavior of always writing type id.
+ *
+ * @since 2.22
+ */
+ public OptBoolean writeTypeIdForDefaultImpl() default OptBoolean.DEFAULT;
+
+ /*
+ /**********************************************************************
+ /* Helper classes
+ /**********************************************************************
+ */
+
+ /**
+ * This marker class that is only to be used with defaultImpl
+ * annotation property, to indicate that there is no default implementation
+ * specified.
+ *
+ * @deprecated Since 2.5, use any Annotation type (such as {@link JsonTypeInfo}),
+ * if such behavior is needed; this is rarely necessary.
+ */
+ @Deprecated // since 2.5
+ public abstract static class None {}
+
/*
/**********************************************************************
/* Value class used to enclose information, allow for
@@ -399,14 +420,23 @@ public static class Value
protected final boolean _idVisible;
protected final Boolean _requireTypeIdForSubtypes;
+ /**
+ * @since 2.22
+ */
+ protected final Boolean _writeTypeIdForDefaultImpl;
+
/*
/**********************************************************************
/* Construction
/**********************************************************************
*/
+ /**
+ * @since 2.22
+ */
protected Value(Id idType, As inclusionType,
- String propertyName, Class defaultImpl, boolean idVisible, Boolean requireTypeIdForSubtypes)
+ String propertyName, Class defaultImpl, boolean idVisible,
+ Boolean requireTypeIdForSubtypes, Boolean writeTypeIdForDefaultImpl)
{
_defaultImpl = defaultImpl;
_idType = idType;
@@ -414,10 +444,25 @@ protected Value(Id idType, As inclusionType,
_propertyName = propertyName;
_idVisible = idVisible;
_requireTypeIdForSubtypes = requireTypeIdForSubtypes;
+ _writeTypeIdForDefaultImpl = writeTypeIdForDefaultImpl;
}
- public static Value construct(Id idType, As inclusionType,
+ /**
+ * @deprecated Since 2.22 use the 7-argument overload
+ */
+ @Deprecated
+ protected Value(Id idType, As inclusionType,
String propertyName, Class defaultImpl, boolean idVisible, Boolean requireTypeIdForSubtypes)
+ {
+ this(idType, inclusionType, propertyName, defaultImpl, idVisible, requireTypeIdForSubtypes, null);
+ }
+
+ /**
+ * @since 2.22
+ */
+ public static Value construct(Id idType, As inclusionType,
+ String propertyName, Class defaultImpl, boolean idVisible,
+ Boolean requireTypeIdForSubtypes, Boolean writeTypeIdForDefaultImpl)
{
// couple of overrides we need to apply here. First: if no propertyName specified,
// use Id-specific property name
@@ -433,7 +478,19 @@ public static Value construct(Id idType, As inclusionType,
if ((defaultImpl == null) || defaultImpl.isAnnotation()) {
defaultImpl = null;
}
- return new Value(idType, inclusionType, propertyName, defaultImpl, idVisible, requireTypeIdForSubtypes);
+ return new Value(idType, inclusionType, propertyName, defaultImpl, idVisible,
+ requireTypeIdForSubtypes, writeTypeIdForDefaultImpl);
+ }
+
+ /**
+ * @deprecated Since 2.22 use the 7-argument overload
+ */
+ @Deprecated
+ public static Value construct(Id idType, As inclusionType,
+ String propertyName, Class defaultImpl, boolean idVisible,
+ Boolean requireTypeIdForSubtypes)
+ {
+ return construct(idType, inclusionType, propertyName, defaultImpl, idVisible, requireTypeIdForSubtypes, null);
}
public static Value from(JsonTypeInfo src) {
@@ -441,7 +498,9 @@ public static Value from(JsonTypeInfo src) {
return null;
}
return construct(src.use(), src.include(),
- src.property(), src.defaultImpl(), src.visible(), src.requireTypeIdForSubtypes().asBoolean());
+ src.property(), src.defaultImpl(), src.visible(),
+ src.requireTypeIdForSubtypes().asBoolean(),
+ src.writeTypeIdForDefaultImpl().asBoolean());
}
/*
@@ -452,32 +511,47 @@ public static Value from(JsonTypeInfo src) {
public Value withDefaultImpl(Class impl) {
return (impl == _defaultImpl) ? this :
- new Value(_idType, _inclusionType, _propertyName, impl, _idVisible, _requireTypeIdForSubtypes);
+ new Value(_idType, _inclusionType, _propertyName, impl, _idVisible,
+ _requireTypeIdForSubtypes, _writeTypeIdForDefaultImpl);
}
public Value withIdType(Id idType) {
return (idType == _idType) ? this :
- new Value(idType, _inclusionType, _propertyName, _defaultImpl, _idVisible, _requireTypeIdForSubtypes);
+ new Value(idType, _inclusionType, _propertyName, _defaultImpl, _idVisible,
+ _requireTypeIdForSubtypes, _writeTypeIdForDefaultImpl);
}
public Value withInclusionType(As inclusionType) {
return (inclusionType == _inclusionType) ? this :
- new Value(_idType, inclusionType, _propertyName, _defaultImpl, _idVisible, _requireTypeIdForSubtypes);
+ new Value(_idType, inclusionType, _propertyName, _defaultImpl, _idVisible,
+ _requireTypeIdForSubtypes, _writeTypeIdForDefaultImpl);
}
public Value withPropertyName(String propName) {
return (propName == _propertyName) ? this :
- new Value(_idType, _inclusionType, propName, _defaultImpl, _idVisible, _requireTypeIdForSubtypes);
+ new Value(_idType, _inclusionType, propName, _defaultImpl, _idVisible,
+ _requireTypeIdForSubtypes, _writeTypeIdForDefaultImpl);
}
public Value withIdVisible(boolean visible) {
return (visible == _idVisible) ? this :
- new Value(_idType, _inclusionType, _propertyName, _defaultImpl, visible, _requireTypeIdForSubtypes);
+ new Value(_idType, _inclusionType, _propertyName, _defaultImpl, visible,
+ _requireTypeIdForSubtypes, _writeTypeIdForDefaultImpl);
}
-
+
public Value withRequireTypeIdForSubtypes(Boolean requireTypeIdForSubtypes) {
return (_requireTypeIdForSubtypes == requireTypeIdForSubtypes) ? this :
- new Value(_idType, _inclusionType, _propertyName, _defaultImpl, _idVisible, requireTypeIdForSubtypes);
+ new Value(_idType, _inclusionType, _propertyName, _defaultImpl, _idVisible,
+ requireTypeIdForSubtypes, _writeTypeIdForDefaultImpl);
+ }
+
+ /**
+ * @since 2.22
+ */
+ public Value withWriteTypeIdForDefaultImpl(Boolean writeTypeIdForDefaultImpl) {
+ return (_writeTypeIdForDefaultImpl == writeTypeIdForDefaultImpl) ? this :
+ new Value(_idType, _inclusionType, _propertyName, _defaultImpl, _idVisible,
+ _requireTypeIdForSubtypes, writeTypeIdForDefaultImpl);
}
/*
@@ -498,6 +572,18 @@ public Class valueFor() {
public boolean getIdVisible() { return _idVisible; }
public Boolean getRequireTypeIdForSubtypes() { return _requireTypeIdForSubtypes; }
+ /**
+ * @since 2.22
+ */
+ public Boolean getWriteTypeIdForDefaultImpl() { return _writeTypeIdForDefaultImpl; }
+
+ /**
+ * @since 2.22
+ */
+ public boolean shouldWriteTypeIdForDefaultImpl() {
+ return (_writeTypeIdForDefaultImpl == null) || _writeTypeIdForDefaultImpl.booleanValue();
+ }
+
/**
* Static helper method for simple(r) checking of whether there's a Value instance
* that indicates that polymorphic handling is (to be) enabled.
@@ -516,11 +602,11 @@ public static boolean isEnabled(JsonTypeInfo.Value v) {
@Override
public String toString() {
- return String.format("JsonTypeInfo.Value(idType=%s,includeAs=%s,propertyName=%s,defaultImpl=%s,idVisible=%s"
- + ",requireTypeIdForSubtypes=%s)",
+ return String.format("JsonTypeInfo.Value(idType=%s,includeAs=%s,propertyName=%s,defaultImpl=%s,idVisible=%s"
+ + ",requireTypeIdForSubtypes=%s,writeTypeIdForDefaultImpl=%s)",
_idType, _inclusionType, _propertyName,
((_defaultImpl == null) ? "NULL" : _defaultImpl.getName()),
- _idVisible, _requireTypeIdForSubtypes);
+ _idVisible, _requireTypeIdForSubtypes, _writeTypeIdForDefaultImpl);
}
@Override
@@ -530,8 +616,9 @@ public int hashCode() {
hashCode = 31 * hashCode + (_inclusionType != null ? _inclusionType.hashCode() : 0);
hashCode = 31 * hashCode + (_propertyName != null ? _propertyName.hashCode() : 0);
hashCode = 31 * hashCode + (_defaultImpl != null ? _defaultImpl.hashCode() : 0);
- hashCode = 31 * hashCode + (_requireTypeIdForSubtypes ? 11 : -17);
+ hashCode = 31 * hashCode + Objects.hashCode(_requireTypeIdForSubtypes);
hashCode = 31 * hashCode + (_idVisible ? 11 : -17);
+ hashCode = 31 * hashCode + Objects.hashCode(_writeTypeIdForDefaultImpl);
return hashCode;
}
@@ -551,6 +638,7 @@ private static boolean _equals(Value a, Value b)
&& (a._idVisible == b._idVisible)
&& Objects.equals(a._propertyName, b._propertyName)
&& Objects.equals(a._requireTypeIdForSubtypes, b._requireTypeIdForSubtypes)
+ && Objects.equals(a._writeTypeIdForDefaultImpl, b._writeTypeIdForDefaultImpl)
;
}
}
diff --git a/src/test/java/com/fasterxml/jackson/annotation/JsonIncludePropertiesTest.java b/src/test/java/com/fasterxml/jackson/annotation/JsonIncludePropertiesTest.java
index 3b88b8e0..8804f196 100644
--- a/src/test/java/com/fasterxml/jackson/annotation/JsonIncludePropertiesTest.java
+++ b/src/test/java/com/fasterxml/jackson/annotation/JsonIncludePropertiesTest.java
@@ -70,7 +70,7 @@ public void testWithOverridesAll() {
@Test
public void testWithOverridesEmpty() {
JsonIncludeProperties.Value v = JsonIncludeProperties.Value.from(Bogus.class.getAnnotation(JsonIncludeProperties.class));
- v = v.withOverrides(new JsonIncludeProperties.Value(Collections.emptySet()));
+ v = v.withOverrides(new JsonIncludeProperties.Value(Collections.emptySet(), false));
Set included = v.getIncluded();
assertEquals(0, included.size());
}
@@ -78,7 +78,7 @@ public void testWithOverridesEmpty() {
@Test
public void testWithOverridesMerge() {
JsonIncludeProperties.Value v = JsonIncludeProperties.Value.from(Bogus.class.getAnnotation(JsonIncludeProperties.class));
- v = v.withOverrides(new JsonIncludeProperties.Value(_set("foo")));
+ v = v.withOverrides(new JsonIncludeProperties.Value(_set("foo"), false));
Set included = v.getIncluded();
assertEquals(1, included.size());
assertEquals(_set("foo"), included);
diff --git a/src/test/java/com/fasterxml/jackson/annotation/JsonTypeInfoTest.java b/src/test/java/com/fasterxml/jackson/annotation/JsonTypeInfoTest.java
index 6c8a2bfa..32862640 100644
--- a/src/test/java/com/fasterxml/jackson/annotation/JsonTypeInfoTest.java
+++ b/src/test/java/com/fasterxml/jackson/annotation/JsonTypeInfoTest.java
@@ -23,6 +23,15 @@ private final static class Anno2 { }
defaultImpl = Void.class)
private final static class Anno3 { }
+ @JsonTypeInfo(use = JsonTypeInfo.Id.CLASS, visible = true,
+ defaultImpl = Void.class,
+ writeTypeIdForDefaultImpl = OptBoolean.FALSE)
+ private final static class Anno4 { }
+
+ @JsonTypeInfo(use = JsonTypeInfo.Id.CLASS,
+ writeTypeIdForDefaultImpl = OptBoolean.TRUE)
+ private final static class Anno5 { }
+
@Test
public void testEmpty() {
// 07-Mar-2017, tatu: Important to distinguish "none" from 'empty' value...
@@ -56,8 +65,8 @@ public void testFromAnnotation() throws Exception
assertFalse(v1.equals(v2));
assertFalse(v2.equals(v1));
- assertEquals("JsonTypeInfo.Value(idType=CLASS,includeAs=PROPERTY,propertyName=@class,defaultImpl=NULL,idVisible=true,requireTypeIdForSubtypes=true)", v1.toString());
- assertEquals("JsonTypeInfo.Value(idType=NAME,includeAs=EXTERNAL_PROPERTY,propertyName=ext,defaultImpl=java.lang.Void,idVisible=false,requireTypeIdForSubtypes=false)", v2.toString());
+ assertEquals("JsonTypeInfo.Value(idType=CLASS,includeAs=PROPERTY,propertyName=@class,defaultImpl=NULL,idVisible=true,requireTypeIdForSubtypes=true,writeTypeIdForDefaultImpl=null)", v1.toString());
+ assertEquals("JsonTypeInfo.Value(idType=NAME,includeAs=EXTERNAL_PROPERTY,propertyName=ext,defaultImpl=java.lang.Void,idVisible=false,requireTypeIdForSubtypes=false,writeTypeIdForDefaultImpl=null)", v2.toString());
// Let's also verify JDK serializability
byte[] b = jdkSerialize(v1);
@@ -115,7 +124,100 @@ public void testDefaultValueForRequireTypeIdForSubtypes() {
assertNull(v3.getRequireTypeIdForSubtypes());
// toString()
- assertEquals("JsonTypeInfo.Value(idType=NAME,includeAs=EXTERNAL_PROPERTY,propertyName=ext,"
- + "defaultImpl=java.lang.Void,idVisible=false,requireTypeIdForSubtypes=null)", v3.toString());
+ assertEquals("JsonTypeInfo.Value(idType=NAME,includeAs=EXTERNAL_PROPERTY,propertyName=ext,"
+ + "defaultImpl=java.lang.Void,idVisible=false,requireTypeIdForSubtypes=null,writeTypeIdForDefaultImpl=null)", v3.toString());
+ }
+
+ // [annotations#342]
+ @Test
+ public void testWriteTypeIdForDefaultImplFromAnnotation() {
+ // Anno4: writeTypeIdForDefaultImpl = FALSE
+ JsonTypeInfo.Value v4 = JsonTypeInfo.Value.from(Anno4.class.getAnnotation(JsonTypeInfo.class));
+ assertEquals(Boolean.FALSE, v4.getWriteTypeIdForDefaultImpl());
+ assertFalse(v4.shouldWriteTypeIdForDefaultImpl());
+
+ // Anno5: writeTypeIdForDefaultImpl = TRUE
+ JsonTypeInfo.Value v5 = JsonTypeInfo.Value.from(Anno5.class.getAnnotation(JsonTypeInfo.class));
+ assertEquals(Boolean.TRUE, v5.getWriteTypeIdForDefaultImpl());
+ assertTrue(v5.shouldWriteTypeIdForDefaultImpl());
+
+ // Anno3: writeTypeIdForDefaultImpl not set (DEFAULT -> null)
+ JsonTypeInfo.Value v3 = JsonTypeInfo.Value.from(Anno3.class.getAnnotation(JsonTypeInfo.class));
+ assertNull(v3.getWriteTypeIdForDefaultImpl());
+ // default should be treated as "write" (true)
+ assertTrue(v3.shouldWriteTypeIdForDefaultImpl());
+ }
+
+ // [annotations#342]
+ @Test
+ public void testWithWriteTypeIdForDefaultImpl() {
+ JsonTypeInfo.Value empty = JsonTypeInfo.Value.EMPTY;
+ assertNull(empty.getWriteTypeIdForDefaultImpl());
+ assertTrue(empty.shouldWriteTypeIdForDefaultImpl());
+
+ // Mutate to FALSE
+ JsonTypeInfo.Value vFalse = empty.withWriteTypeIdForDefaultImpl(Boolean.FALSE);
+ assertEquals(Boolean.FALSE, vFalse.getWriteTypeIdForDefaultImpl());
+ assertFalse(vFalse.shouldWriteTypeIdForDefaultImpl());
+
+ // Mutate to TRUE
+ JsonTypeInfo.Value vTrue = empty.withWriteTypeIdForDefaultImpl(Boolean.TRUE);
+ assertEquals(Boolean.TRUE, vTrue.getWriteTypeIdForDefaultImpl());
+ assertTrue(vTrue.shouldWriteTypeIdForDefaultImpl());
+
+ // Mutate back to null
+ JsonTypeInfo.Value vNull = vFalse.withWriteTypeIdForDefaultImpl(null);
+ assertNull(vNull.getWriteTypeIdForDefaultImpl());
+ assertTrue(vNull.shouldWriteTypeIdForDefaultImpl());
+
+ // Same value returns same instance
+ assertSame(vFalse, vFalse.withWriteTypeIdForDefaultImpl(Boolean.FALSE));
+ assertSame(vTrue, vTrue.withWriteTypeIdForDefaultImpl(Boolean.TRUE));
+ }
+
+ // [annotations#342]
+ @Test
+ public void testWriteTypeIdForDefaultImplEqualsAndHashCode() {
+ JsonTypeInfo.Value v1 = JsonTypeInfo.Value.EMPTY.withWriteTypeIdForDefaultImpl(Boolean.TRUE);
+ JsonTypeInfo.Value v2 = JsonTypeInfo.Value.EMPTY.withWriteTypeIdForDefaultImpl(Boolean.TRUE);
+ JsonTypeInfo.Value v3 = JsonTypeInfo.Value.EMPTY.withWriteTypeIdForDefaultImpl(Boolean.FALSE);
+ JsonTypeInfo.Value vNull = JsonTypeInfo.Value.EMPTY.withWriteTypeIdForDefaultImpl(null);
+
+ assertEquals(v1, v2);
+ assertEquals(v1.hashCode(), v2.hashCode());
+
+ assertNotEquals(v1, v3);
+ assertNotEquals(v1, vNull);
+ assertNotEquals(v3, vNull);
+ }
+
+ // [annotations#342]
+ @Test
+ public void testWriteTypeIdForDefaultImplToString() {
+ JsonTypeInfo.Value vFalse = JsonTypeInfo.Value.EMPTY.withWriteTypeIdForDefaultImpl(Boolean.FALSE);
+ assertTrue(vFalse.toString().contains("writeTypeIdForDefaultImpl=false"));
+
+ JsonTypeInfo.Value vTrue = JsonTypeInfo.Value.EMPTY.withWriteTypeIdForDefaultImpl(Boolean.TRUE);
+ assertTrue(vTrue.toString().contains("writeTypeIdForDefaultImpl=true"));
+ }
+
+ // [annotations#342]
+ @Test
+ public void testWriteTypeIdForDefaultImplConstruct() {
+ JsonTypeInfo.Value v = JsonTypeInfo.Value.construct(
+ JsonTypeInfo.Id.CLASS, JsonTypeInfo.As.PROPERTY,
+ null, Void.class, false, null, Boolean.FALSE);
+ assertEquals(Boolean.FALSE, v.getWriteTypeIdForDefaultImpl());
+ assertFalse(v.shouldWriteTypeIdForDefaultImpl());
+ }
+
+ // [annotations#342]
+ @Test
+ public void testWriteTypeIdForDefaultImplSerialization() throws Exception {
+ JsonTypeInfo.Value v = JsonTypeInfo.Value.EMPTY.withWriteTypeIdForDefaultImpl(Boolean.FALSE);
+ byte[] b = jdkSerialize(v);
+ JsonTypeInfo.Value deser = jdkDeserialize(b);
+ assertEquals(v, deser);
+ assertEquals(Boolean.FALSE, deser.getWriteTypeIdForDefaultImpl());
}
}