MapStruct：如何使用映射器使用复合键 JPA 映射视图对象？答案

【问题标题】：MapStruct: How to use mapper to map View Objects with Composite Key JPA?MapStruct：如何使用映射器使用复合键 JPA 映射视图对象？
【发布时间】：2020-05-08 11:13:59
【问题描述】：

我有如下目标实体：

public class ApplicationUsage {
    @Id
    private ApplicationUsagePK appUsage;    //Guid  No documentation available.
    private String name;
    .
    .
    public ApplicationUsage(String id, Integer compId) {
       this.appUsage = new ApplicationUsagePK(id, compId); //This is present in ApplicationUsagePK initiated here which acts are composite key
    }

源对象如下：

public class ApplicationUsage {

    @SerializedName("id")
    @Expose
    private String id;
    @SerializedName("name")
    @Expose
    private String name;

我需要将源对象的 ID 映射到 applicationUsage(String id 并且 CompID 来自其他变量，它需要映射到 applicationUsage(.., Integer compId) em>

上述类或映射器需要进行哪些更改才能实现相同的效果？

以下是当前映射器：

@Mapper
public interface ApplicationUsageMapper {
    ApplicationUsageMapper MAPPER = Mappers.getMapper( ApplicationUsageMapper.class );

    ApplicationUsage entityToDao(com.inte.meow.vo.computer.ApplicationUsage source);
}

不好的方式：

我使用了不好的方法来解决这个问题，你可以理解以下内容：

ApplicationUsage aUsage = ApplicationUsageMapper.MAPPER.entityToDao(agreement.getBody());
aUsage.initiateApplicationUsage(agreement.getBody().getId(), compId);

【问题讨论】：

标签： jpa mapstruct

【解决方案1】：

您可以使用@Context 注释来做到这一点

@Mapper
public interface ApplicationUsageMapper {
    ApplicationUsageMapper MAPPER = Mappers.getMapper( ApplicationUsageMapper.class );

    @Mapping(target = "appUsage", source = "source", qualifiedByName = "getAppUsage")
    ApplicationUsage entityToDao(com.inte.meow.vo.computer.ApplicationUsage source, @Context Integer compId);

    @Named("getAppUsage")
    default ApplicationUsagePK toAppUsage(com.inte.meow.vo.computer.ApplicationUsage source, @Context Integer compId) {
        return new ApplicationUsagePK (source.getId(), compId));
    }
}

【讨论】：