地图结构。通过表达式映射列表元素的字段

Question

下午好！有一个对象包含类型为 List 的字段，是否可以通过表达式参数在注释中生成的值来设置类型 T 的每个（某些）字段？

例如：

目标对象：

public class CustomList<T extends CustomEntity> extends CustomEntity {
    
    private List<T> field;
    
    public CustomList() {
        field = new ArrayList();
    }
}

映射器接口：

@Mapper
public interface Mapper {
    @Mapping(target = "java(field.foreach(f -> f.getId))", expression = "java(UUID.randomUUID().toString())")
    CustomList<SomeObject> map (Object object);
}

如何实现这样的想法？在文档中，我只找到了带有 1:1 映射的示例。

已编辑：

此外，我尝试使用这个：

public class IterableNonIntegrableUtil {

  @SetElements
  public CustomList<SomeObject> map(Object object) {
    CustomList<SomeObject> customList= new CustomList<>();
    customList.getField()
        .forEach(item -> item.setUid(UUID.randomUUID().toString()));
    return customList;
  }}




@Qualifier
@Target(ElementType.METHOD)
@Retention(RetentionPolicy.CLASS)
public @interface SetElements{}



Mapper interface:
@Mapper(uses = IterableNonIntegrableUtil.class)
    public interface Mapper {
        @Mapping(target = "field", souce = "object", 
qualifiedBy=SetElements.class)
        CustomList<SomeObject> map (Object object);}

但在这种情况下，我对限定符有一些错误。

Answer 1

可以通过将对象映射到相同的类型：

CustomList<SomeObject> map(CustomList<SomeObject> src);

// in case you only want to set the ones that are null.
@Mapping(target = "someField1", default = "someValue")
@Mapping(target = "someField2", defaultExpression = "java(someMethod())")
// in case you always want to set the value.
@Mapping(target = "someField3", constant = "someValue")
@Mapping(target = "someField4", expression = "java(someMethod())")
SomeObject map(SomeObject src);

我自己会考虑在您构造对象时设置默认值。

例如：

class SomeObject {
    private String someField;

    /**
      * When called with a null or a blank value, the default value will be restored.
      */
    void setSomeField(String value) {
        // there is probably an utility out there which can make this a one-liner.
        if (value != null && !value.isBlank()){
            someField = value;
        } else {
            someField = "defaultValue";
        }
    }
}

地图结构。通过表达式映射列表元素的字段

MapStruct. Mapping fields of list element by expression

java

mapping

mapstruct