Question

好吧，我在MapStruct中有以下Mapper：

 @Mapping(source = "payload.after", target = "payload")
 TargetEntity toTarget(SourceEntity source);

有时payload.after为空，我需要填充另一个名为payload.before的属性。像这样：

 @Mapping(source = "payload.after", target = "payload")
   //OR, if payload.after is null
 @Mapping(source = "payload.before", target = "payload")
 TargetEntity toTarget(SourceEntity source);

我尝试过以这种方式使用，但没有用：

 @Mapping(source = "payload.after", target = "payload", defaultValue = "payload.before")
 TargetEntity toTarget(SourceEntity source);

有办法吗？

Answer 1

从MapStruct文档中，我看到只有您可以使用预定义的值：https://mapstruct.org/documentation/stable/reference/html/#default-values-and-constants

但是您可以通过在MapStruct文档示例中使用@AfterMapping或@BeforeMapping之类的注释来轻松实现：）

编辑：

@Mapping(target = "otherTargetField", source = "otherSrcField")
TargetEntity toTarget(SourceEntity source);

@AfterMapping
void toTargetAfterMapping(@MappingTarget TargetEntity, SourceEntity source) {
   // Your after mapping logic with payload.before and payload.after
}

MapStruct自动解析在最后一个return语句之前的映射方法的末尾调用此方法。如果您想了解更多信息，请参见MapStruct docs - customising mappings with before and after。

您可以使用的另一种方法是defaultExpression

@Mapping(target = "payload", source = "payload.after", defaultExpression = "java(source.getPayload().getBefore())")
TargetEntity toTarget(SourceEntity source);

当Source为null时，另一个bean属性的默认值。MapStruct

1 个答案: