Mapper (MapStruct 1.4.2.Final)

@Target(value=TYPE)
 @Retention(value=CLASS)
public @interface Mapper

Marks an interface or abstract class as a mapper and activates the generation of a implementation of that type via MapStruct.

Example 1: Creating mapper


 @Mapper
 public interface CarMapper {
     CarDto toCarDto(Car source);
 }

Example 2: Use additional mappers with parameters uses(), componentModel() and injectionStrategy()


 // we have MarkMapper (map field "mark" to field "name" to upper case)
 @Mapper(componentModel = "spring")
 public class MarkMapper {
     public String mapMark(String mark) {
         return mark.toUpperCase();
     }
 }
 // we have CarMapper
 @Mapper(
      componentModel = "spring",
      uses = MarkMapper.class,
      injectionStrategy = InjectionStrategy.CONSTRUCTOR)
 public interface CarMapper {
     @Mapping(source = "mark", target = "name")
     CarDto convertMap(CarEntity carEntity);
 }


 // generates
 @Component
 public class CarMapperImpl implements CarMapper {
     private final MarkMapper markMapper;
     @Autowired
     public CarMapperImpl(MarkMapper markMapper) {
         this.markMapper = markMapper;
     }
     @Override
     public CarDto convertMap(CarEntity carEntity) {
         if ( carEntity == null ) {
             return null;
         }
         CarDto carDto = new CarDto();
         carDto.setName( markMapper.mapMark( carEntity.getMark() ) );
         return carDto;
     }
 }

Author:: Gunnar Morling

Optional Element Summary

Optional Elements
Modifier and Type	Optional Element and Description
`Builder`	`builder` The information that should be used for the builder mappings.
`CollectionMappingStrategy`	`collectionMappingStrategy` The strategy to be applied when propagating the value of collection-typed properties.
`String`	`componentModel` Specifies the component model to which the generated mapper should adhere.
`Class<?>`	`config` A class annotated with `MapperConfig` which should be used as configuration template.
`boolean`	`disableSubMappingMethodsGeneration` If MapStruct could not find another mapping method or apply an automatic conversion it will try to generate a sub-mapping method between the two beans.
`String`	`implementationName` Specifies the name of the implementation class.
`String`	`implementationPackage` Specifies the target package for the generated implementation.
`Class<?>[]`	`imports` Additional types for which an import statement is to be added to the generated mapper implementation class.
`InjectionStrategy`	`injectionStrategy` Determines whether to use field or constructor injection.
`Class<? extends Annotation>`	`mappingControl` Allows detailed control over the mapping process.
`MappingInheritanceStrategy`	`mappingInheritanceStrategy` The strategy to use for applying method-level configuration annotations of prototype methods in the interface specified with `config()`.
`NullValueCheckStrategy`	`nullValueCheckStrategy` Determines when to include a null check on the source property value of a bean mapping.
`NullValueMappingStrategy`	`nullValueMappingStrategy` The strategy to be applied when `null` is passed as source argument value to the methods of this mapper.
`NullValuePropertyMappingStrategy`	`nullValuePropertyMappingStrategy` The strategy to be applied when a source bean property is `null` or not present.
`ReportingPolicy`	`typeConversionPolicy` How lossy (narrowing) conversion, for instance long to integer should be reported.
`Class<? extends Exception>`	`unexpectedValueMappingException` Exception that should be thrown by the generated code if no mapping matches for enums.
`ReportingPolicy`	`unmappedSourcePolicy` How unmapped properties of the source type of a mapping should be reported.
`ReportingPolicy`	`unmappedTargetPolicy` How unmapped properties of the target type of a mapping should be reported.
`Class<?>[]`	`uses` Other mapper types used by this mapper.

- Element Detail
  - uses
```
public abstract Class<?>[] uses
```
    Other mapper types used by this mapper. May be hand-written classes or other mappers generated by MapStruct. No cycle between generated mapper classes must be created.
    
    Returns:
    
    The mapper types used by this mapper.
    
    Default:
    
    {}
- - imports
```
public abstract Class<?>[] imports
```
    Additional types for which an import statement is to be added to the generated mapper implementation class. This allows to refer to those types from within mapping expressions given via Mapping.expression(), Mapping.defaultExpression() or using their simple name rather than their fully-qualified name.
    
    Returns:
    
    classes to add in the imports of the generated implementation.
    
    Default:
    
    {}
- - unmappedSourcePolicy
```
public abstract ReportingPolicy unmappedSourcePolicy
```
    How unmapped properties of the source type of a mapping should be reported. The method overrides an unmappedSourcePolicy set in a central configuration set by config()
    
    Returns:
    
    The reporting policy for unmapped source properties.
    
    Since:
    
    1.3
    
    Default:
    
    org.mapstruct.ReportingPolicy.IGNORE
- - unmappedTargetPolicy
```
public abstract ReportingPolicy unmappedTargetPolicy
```
    How unmapped properties of the target type of a mapping should be reported. The method overrides an unmappedTargetPolicy set in a central configuration set by config()
    
    Returns:
    
    The reporting policy for unmapped target properties.
    
    Default:
    
    org.mapstruct.ReportingPolicy.WARN
- - typeConversionPolicy
```
public abstract ReportingPolicy typeConversionPolicy
```
    How lossy (narrowing) conversion, for instance long to integer should be reported. The method overrides an typeConversionPolicy set in a central configuration set by config()
    
    Returns:
    
    The reporting policy for unmapped target properties.
    
    Since:
    
    1.3
    
    Default:
    
    org.mapstruct.ReportingPolicy.IGNORE
- - componentModel
```
public abstract String componentModel
```
    Specifies the component model to which the generated mapper should adhere. Supported values are
    - default: the mapper uses no component model, instances are typically retrieved via Mappers.getMapper(Class)
    - cdi: the generated mapper is an application-scoped CDI bean and can be retrieved via @Inject
    - spring: the generated mapper is a Spring bean and can be retrieved via @Autowired
    - jsr330: the generated mapper is annotated with @javax.inject.Named and @Singleton, and can be retrieved via @Inject
    The method overrides an unmappedTargetPolicy set in a central configuration set by config()
    Returns:
    
    The component model for the generated mapper.
    
    Default:
    
    "default"
- - implementationName
```
public abstract String implementationName
```
    Specifies the name of the implementation class. The <CLASS_NAME> will be replaced by the interface/abstract class name.
    Defaults to postfixing the name with Impl: <CLASS_NAME>Impl
    
    Returns:
    
    The implementation name.
    
    See Also:
    
    implementationPackage()
    
    Default:
    
    "<CLASS_NAME>Impl"
- - implementationPackage
```
public abstract String implementationPackage
```
    Specifies the target package for the generated implementation. The <PACKAGE_NAME> will be replaced by the interface's or abstract class' package.
    Defaults to using the same package as the mapper interface/abstract class
    
    Returns:
    
    the implementation package.
    
    See Also:
    
    implementationName()
    
    Default:
    
    "<PACKAGE_NAME>"
- - config
```
public abstract Class<?> config
```
    A class annotated with MapperConfig which should be used as configuration template. Any settings given via Mapper will take precedence over the settings from the referenced configuration source. The list of referenced mappers will contain all mappers given via uses() and MapperConfig.uses().
    
    Returns:
    
    A class which should be used as configuration template.
    
    Default:
    
    void.class
- - collectionMappingStrategy
```
public abstract CollectionMappingStrategy collectionMappingStrategy
```
    The strategy to be applied when propagating the value of collection-typed properties. By default, only JavaBeans accessor methods (setters or getters) will be used, but it is also possible to invoke a corresponding adder method for each element of the source collection (e.g. orderDto.addOrderLine()).
    Any setting given for this attribute will take precedence over MapperConfig.collectionMappingStrategy(), if present.
    
    Returns:
    
    The strategy applied when propagating the value of collection-typed properties.
    
    Default:
    
    org.mapstruct.CollectionMappingStrategy.ACCESSOR_ONLY
- - nullValueMappingStrategy
```
public abstract NullValueMappingStrategy nullValueMappingStrategy
```
    The strategy to be applied when null is passed as source argument value to the methods of this mapper. If no strategy is configured, the strategy given via MapperConfig.nullValueMappingStrategy() will be applied, using NullValueMappingStrategy.RETURN_NULL by default.
    
    Returns:
    
    The strategy to be applied when null is passed as source value to the methods of this mapper.
    
    Default:
    
    org.mapstruct.NullValueMappingStrategy.RETURN_NULL
- - nullValuePropertyMappingStrategy
```
public abstract NullValuePropertyMappingStrategy nullValuePropertyMappingStrategy
```
    The strategy to be applied when a source bean property is null or not present. If no strategy is configured, the strategy given via MapperConfig.nullValuePropertyMappingStrategy() will be applied, NullValuePropertyMappingStrategy.SET_TO_NULL will be used by default.
    
    Returns:
    
    The strategy to be applied when null is passed as source property value or the source property is not present.
    
    Since:
    
    1.3
    
    Default:
    
    org.mapstruct.NullValuePropertyMappingStrategy.SET_TO_NULL
- - mappingInheritanceStrategy
```
public abstract MappingInheritanceStrategy mappingInheritanceStrategy
```
    The strategy to use for applying method-level configuration annotations of prototype methods in the interface specified with config(). Annotations that can be inherited are for example Mapping, IterableMapping, MapMapping, or BeanMapping.
    If no strategy is configured, the strategy given via MapperConfig.mappingInheritanceStrategy() will be applied, using MappingInheritanceStrategy.EXPLICIT as default.
    
    Returns:
    
    The strategy to use for applying @Mapping configurations of prototype methods in the interface specified with config().
    
    Default:
    
    org.mapstruct.MappingInheritanceStrategy.EXPLICIT
- - nullValueCheckStrategy
```
public abstract NullValueCheckStrategy nullValueCheckStrategy
```
    Determines when to include a null check on the source property value of a bean mapping. Can be overridden by the one on MapperConfig, BeanMapping or Mapping.
    
    Returns:
    
    strategy how to do null checking
    
    Default:
    
    org.mapstruct.NullValueCheckStrategy.ON_IMPLICIT_CONVERSION
- - injectionStrategy
```
public abstract InjectionStrategy injectionStrategy
```
    Determines whether to use field or constructor injection. This is only used on annotated based component models such as CDI, Spring and JSR 330. If no strategy is configured, InjectionStrategy.FIELD will be used as default.
    
    Returns:
    
    strategy how to inject
    
    Default:
    
    org.mapstruct.InjectionStrategy.FIELD
- - disableSubMappingMethodsGeneration
```
public abstract boolean disableSubMappingMethodsGeneration
```
    If MapStruct could not find another mapping method or apply an automatic conversion it will try to generate a sub-mapping method between the two beans. If this property is set to true MapStruct will not try to automatically generate sub-mapping methods.
    Can be configured by the MapperConfig.disableSubMappingMethodsGeneration() as well.
    Note: If you need to use disableSubMappingMethodsGeneration please contact the MapStruct team at mapstruct.org or github.com/mapstruct/mapstruct to share what problem you are facing with the automatic sub-mapping generation.
    
    Returns:
    
    whether the automatic generation of sub-mapping methods is disabled
    
    Since:
    
    1.2
    
    Default:
    
    false
- - builder
```
public abstract Builder builder
```
    The information that should be used for the builder mappings. This can be used to define custom build methods for the builder strategy that one uses. If no builder is defined the builder given via MapperConfig.builder() will be applied.
    NOTE: In case no builder is defined here, in BeanMapping or MapperConfig and there is a single build method, then that method would be used.
    If the builder is defined and there is a single method that does not match the name of the build method then a compile error will occur
    
    Returns:
    
    the builder information
    
    Since:
    
    1.3
    
    Default:
    
    @org.mapstruct.Builder
- - mappingControl
```
public abstract Class<? extends Annotation> mappingControl
```
    Allows detailed control over the mapping process.
    
    Returns:
    
    the mapping control
    
    Since:
    
    1.4
    
    See Also:
    
    DeepClone, NoComplexMapping, MappingControl
    
    Default:
    
    org.mapstruct.control.MappingControl.class
- - unexpectedValueMappingException
```
public abstract Class<? extends Exception> unexpectedValueMappingException
```
    Exception that should be thrown by the generated code if no mapping matches for enums. If no exception is configured, the exception given via MapperConfig.unexpectedValueMappingException() will be used, using IllegalArgumentException by default.
    Note:
    - The defined exception should at least have a constructor with a String parameter.
    - If the defined exception is a checked exception then the enum mapping methods should have that exception in the throws clause.
    Returns:
    
    the exception that should be used in the generated code
    
    Since:
    
    1.4
    
    Default:
    
    java.lang.IllegalArgumentException.class

Annotation Type Mapper

Optional Element Summary

Element Detail

uses

imports

unmappedSourcePolicy

unmappedTargetPolicy

typeConversionPolicy

componentModel

implementationName

implementationPackage

config

collectionMappingStrategy

nullValueMappingStrategy

nullValuePropertyMappingStrategy

mappingInheritanceStrategy

nullValueCheckStrategy

injectionStrategy

disableSubMappingMethodsGeneration

builder

mappingControl

unexpectedValueMappingException