使用 Orika 在包含列表的两个对象之间进行映射

Question

我正在尝试使用 Orika 在包含 List<...> 的两个对象之间进行映射，其中 List 类型是另一个对象，但是尽管在 mapperFactory.classMap(...) 中尝试了映射配置的各种排列，Orika 抛出了一个当我运行我的程序时出现异常。

查看 http://orika-mapper.github.io/orika-docs/mappings-via-classmapbuilder.html 似乎表明映射 List 的语法应该是 parentProperty{childProperty}.

为了这个问题的目的，我简化了我试图映射的对象。源对象是 ToDoTaskListEntity，目标对象是 ToDoTaskListDTO。源对象 ToDoItemEntity 包含定义为 List<ToDoItemEntity> 的列表，目标对象包含定义为 List<ToDoItemDTO>

的相应列表

我的问题是我应该如何在Orika中定义ToDoTaskListEntity和ToDoTaskListDTO之间的映射配置，以便子对象List<ToDoItemEntity>是也映射到各自父对象中的 List<ToDoItemDTO>?

我的映射配置代码如下：

MapperFactory mapperFactory = new DefaultMapperFactory.Builder().build();

mapperFactory.classMap(ToDoItemEntity.class, ToDoItemDTO.class)
    .field("id", "id")
    .field("description", "description")
    .field("status", "status")
    .byDefault()
    .register();

mapperFactory.classMap(ToDoTaskListEntity.class, ToDoTaskListDTO.class)
    .field("listName", "listName")
    .field("toDoItems{id}", "toDoItems{id}")
    .field("toDoItems{description}", "toDoItems{description}")
    .field("toDoItems{status}", "toDoItems{status}")
    .byDefault()
    .register();

调用映射的代码如下：

MapperFacade mapper = mapperFactory.getMapperFacade();
ToDoTaskListDTO toDoTaskListDTO = mapper.map(toDoTaskListEntity, ToDoTaskListDTO.class);

我的源对象代码如下：

public class ToDoTaskListEntity {

    private String ListName;
    private List<ToDoItemEntity> toDoItems;

    // Getters and setters
}

public class ToDoItemEntity {

    private int id;
    private String description;
    private Status status;

    // Getters and setters
}

我的目标对象代码如下：

public class ToDoTaskListDTO {

    private String listName;
    private List<ToDoItemDTO> toDoItems;

    public ToDoTaskListDTO(String listName, List<ToDoItemDTO> toDoItems) {
        this.listName = listName;
        this.toDoItems = toDoItems;
    }

    //Getters but no setters

}

public class ToDoItemDTO {

    private int id;
    private String description;
    private Status status;

    public ToDoItemDTO(int id, String description, Status status) {
        this.id = id;
        this.description = description;
        this.status = status;
    }

    // Getters but no setters
}

Orika抛出的异常如下：

Exception in thread "main" ma.glasnost.orika.MappingException: exception while creating object factory for test.orikademo.ToDoTaskListDTO
-----begin dump of current state-----------------------------
Registered object factories: 1 (approximate size: 25.4 kB)
  [ToDoTaskListDTO] : {}
-------------------------------------------------------------
Registered mappers: 2 (approximate size: 961.5 kB)
  [0] : GeneratedMapper<ToDoItemEntity, ToDoItemDTO> {usedConverters: [], usedMappers: [], usedMapperFacades: [], usedTypes: [] }
  [1] : GeneratedMapper<ToDoTaskListEntity, ToDoTaskListDTO> {usedConverters: [], usedMappers: [], usedMapperFacades: [DefaultBoundMapperFacade<ToDoItemEntity, ToDoItemDTO>], usedTypes: [List<ToDoItemEntity>, List<ToDoItemDTO>] }
-------------------------------------------------------------
Registered concrete types: 5 (approximate size: 122.4 kB)
  [interface java.util.List] : ArrayList<Object>
  [interface java.util.Set] : LinkedHashSet<Object>
  [interface java.util.Collection] : ArrayList<Object>
  [interface java.util.Map$Entry] : MapEntry<Object, Object>
  [interface java.util.Map] : LinkedHashMap<Object, Object>
-------------------------------------------------------------
Resolved strategies: 0 (approximate size: 0.8 kB)
-------------------------------------------------------------
Unenhance strategy: ma.glasnost.orika.unenhance.BaseUnenhancer@292a74d5
-----end dump of current state-------------------------------
    at ma.glasnost.orika.impl.generator.ObjectFactoryGenerator.build(ObjectFactoryGenerator.java:110)
    at ma.glasnost.orika.impl.DefaultMapperFactory.lookupObjectFactory(DefaultMapperFactory.java:1005)
    at ma.glasnost.orika.impl.DefaultMapperFactory.lookupObjectFactory(DefaultMapperFactory.java:925)
    at ma.glasnost.orika.impl.MapperFacadeImpl.resolveMappingStrategy(MapperFacadeImpl.java:218)
    at ma.glasnost.orika.impl.MapperFacadeImpl.map(MapperFacadeImpl.java:734)
    at ma.glasnost.orika.impl.MapperFacadeImpl.map(MapperFacadeImpl.java:714)
    at test.orikademo.App.main(App.java:54)
Caused by: java.lang.NullPointerException
    at ma.glasnost.orika.impl.generator.ObjectFactoryGenerator.addSourceClassConstructor(ObjectFactoryGenerator.java:173)
    at ma.glasnost.orika.impl.generator.ObjectFactoryGenerator.addCreateMethod(ObjectFactoryGenerator.java:124)
    at ma.glasnost.orika.impl.generator.ObjectFactoryGenerator.build(ObjectFactoryGenerator.java:95)
    ... 6 more

Answer 1

我在 Google 组的 Orika discussion group 中发布了相同的问题，并从 Sidi Mohamed 那里得到了以下答案，解决了我的问题。

You do not need any specific mappings for this example, the only issue I can see here is the non default constructor on the DTO side
MapperFactory mapperFactory = new DefaultMapperFactory.Builder().build();
// item class map
mapperFactory.classMap(ToDoItemEntity.class, ToDoItemDTO.class)
    .constrcutorB("id", "description", "status")
    .byDefault()
    .register();

mapperFactory.classMap(ToDoTaskListEntity.class, ToDoTaskListDTO.class)
    .constructorB("listName", "toDoItems")
    .byDefault()
    .register();
To answer your question the expression like toDoItems{id} is used only to project (or flatten) your objects, in this example what you want is to re use your previous mapping definitions (eg. reuse item class map when mapping toDoItems in the second class map) which why Orika is used : to reduce the boilerplate code.

使用 Orika 在包含列表的两个对象之间进行映射

Mapping between two objects that contain a List using Orika

java

mapping

list

orika