mybatis/mybatis-3 · error · UnsupportedOperationException

'" + this.getClass() + "' must override the default method '

Error message

'" + this.getClass() + "' must override the default method 'getGenericGetterType()'.

What it means

The getter-side twin of getGenericSetterType: ObjectWrapper.getGenericGetterType(String) is a default method whose body only throws UnsupportedOperationException naming the class that must override it. It resolves the full generic Type of a readable property for generic-aware TypeHandler selection; wrappers that don't implement it (e.g. CollectionWrapper) throw when it is called.

Source

Thrown at src/main/java/org/apache/ibatis/reflection/wrapper/ObjectWrapper.java:51

  void set(PropertyTokenizer prop, Object value);

  String findProperty(String name, boolean useCamelCaseMapping);

  String[] getGetterNames();

  String[] getSetterNames();

  Class<?> getSetterType(String name);

  Class<?> getGetterType(String name);

  default Entry<Type, Class<?>> getGenericSetterType(String name) {
    throw new UnsupportedOperationException(
        "'" + this.getClass() + "' must override the default method 'getGenericSetterType()'.");
  }

  default Entry<Type, Class<?>> getGenericGetterType(String name) {
    throw new UnsupportedOperationException(
        "'" + this.getClass() + "' must override the default method 'getGenericGetterType()'.");
  }

  boolean hasSetter(String name);

  boolean hasGetter(String name);

  MetaObject instantiatePropertyValue(String name, PropertyTokenizer prop, ObjectFactory objectFactory);

  boolean isCollection();

  void add(Object element);

  <E> void addAll(List<E> element);

}

View on GitHub (pinned to 008069adb1)

Solutions

1. Override getGenericGetterType(String name) in your custom ObjectWrapper (typically delegating to MetaClass/Reflector generic info)
2. Prefer BeanWrapper/MapWrapper, which override the method, when generic resolution is required
3. Do not call generic property type methods on collection wrappers that have no properties

Example fix

// before
class MyWrapper implements ObjectWrapper { /* no getGenericGetterType */ }

// after
@Override
public Entry<Type, Class<?>> getGenericGetterType(String name) {
  Class<?> raw = metaClass.getGetterType(name);
  return Map.Entry.entry(raw, raw);
}

ObjectWrapper w = metaObject.getObjectWrapper();
if (w instanceof org.apache.ibatis.reflection.wrapper.BeanWrapper
    || w instanceof org.apache.ibatis.reflection.wrapper.MapWrapper) {
  var t = w.getGenericGetterType(name);
}

When it happens

Trigger: metaObject.getObjectWrapper().getGenericGetterType(name) invoked on a wrapper without the override; MyBatis parameter/result resolution paths that need the generic element type of a property (e.g. List<Item> items) running against a custom or minimal ObjectWrapper.

Common situations: Custom ObjectWrapper implementations predating the 3.5.x generic-type APIs; upgrading MyBatis where the framework began calling getGenericGetterType during parameter handling; direct API use in reflection utilities.

Related errors

• '" + this.getClass() + "' must override the default method '
• The 2nd arg must be Class or ParameterizedType, but was: {}
• The DefaultObjectWrapperFactory should never be called to pr
• Error creating instance. Cause: {cause}
• Error in result map '{resultMapId}'. Failed to find a constr

AI-assisted analysis of mybatis/mybatis-3@008069adb1 (2026-08-14). Data as JSON: /api/errors/e1e21be2c9c11ce6. Report an issue: GitHub.