如何在Java中将属性映射到整数Mapstruct

Question

我在mapstruct映射器上遇到了问题。当运行mvn clean install（或mvn clean compile）时，我会得到以下错误：

[ERROR] /mapper/EntityMapper.java:[28,7] Can't map property "java.util.List<com.socomec.tseselector.model.Source> architecture.sources
" to "java.lang.Integer architecture.sources". Consider to declare/implement a mapping method: "java.lang.Integer map(java.util.List<com.socomec.tseselector.model.Source> value)".
[ERROR] /mapper/command/TSEProjectCommandMapper.java:[21,16] Can't map property "java.lang.Integer architecture.loads" to "java.util.List<com.socomec.tseselector.model.Load> architecture.loads". Consider to declare/implement a mapping method: "java.util.List<com.socomec.tseselector.model.Load> map(java.lang.Integer value)".

问题是我不知道mapstruct从哪里获得这个“java.lang.Integer Architecture.Loads”。我不明白这个整数是从哪里来的，正如您在我的代码中看到的，没有整数。而且，到目前为止，我在使用类似的映射器时从未遇到过这个错误。

下面是我的实体架构：

public class Architecture {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String name;
    private String imagePath;

    @ManyToMany(cascade = CascadeType.ALL)
    @JoinTable(name="tse_architectures_loads",
            joinColumns = {@JoinColumn(table = "tse_architecture", name = "architecture_id")},
            inverseJoinColumns = {@JoinColumn(table = "tse_load", name = "load_id")}
    )
    private List<Load> loads;

    @ManyToMany(cascade = CascadeType.ALL)
    @JoinTable(name="tse_architectures_sources",
            joinColumns = {@JoinColumn(table = "tse_architecture", name = "architecture_id")},
            inverseJoinColumns = {@JoinColumn(table = "tse_source", name = "source_id")}
    )
    private List<Source> sources;

    private String techno;

    public Architecture() {
        this.loads = new ArrayList<>();
        this.sources = new ArrayList<>();
    }

DTO

public class ArchitectureDto {
    private Long id;
    private String name;
    private String imagePath;
    private List<LoadDto> loadDtos;
    private List<SourceDto> sourceDtos;
    private String techno;

    public ArchitectureDto() {
        this.loadDtos = new ArrayList<>();
        this.sourceDtos = new ArrayList<>();
    }
}

我的映射器：

@Mapper(componentModel = "spring")
public interface ArchitectureMapper extends EntityMapper<ArchitectureDto, Architecture> {

    @Mapping(source = "loads", target = "loadDtos")
    @Mapping(source = "sources", target = "sourceDtos")
    ArchitectureDto toDto(Architecture architecture);
}

public interface EntityMapper<D, E> {

    /**
     * Map a DTO to an Entity
     *
     * @param dto the dto to map
     * @return an Entity
     */
    E toEntity(D dto);

    /**
     * Map an Entity to a DTO
     *
     * @param entity to map to a DTO
     * @return a DTO
     */
    D toDto(E entity);

    /**
     * Map a List of DTOs to a List of Entities
     *
     * @param dtoList the list to map
     * @return a list of Entities
     */
    List<E> toEntity(List<D> dtoList);

    /**
     * Map a list of Entities to a list of DTOs
     *
     * @param entityList the list to map
     * @return a list of DTOs
     */
    List<D> toDto(List<E> entityList);
}

public class Load {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    private String name;
    private String type;
    private String unity;
    private Long sourcePriority1;
    private Long SourcePriority2;
    private Long SourcePriority3;
    private Long kvaValue;
    private Long kwValue;
    private Long pfValue;
    private Long aValue;
    private Long iccValue;

    @JsonIgnore
    @ManyToMany(mappedBy = "loads")
    private List<TSEProject> tseProjects;

    @JsonIgnore
    @ManyToMany(mappedBy = "loadList")
    private List<Architecture> architectures;

    public Load() {
        this.architectures = new ArrayList<>();
        this.tseProjects = new ArrayList<>();
    }

public class Source {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    private String name;
    private String type;
    private String unity;
    private Long quantity;
    private Long kvaValue;
    private Long kwValue;
    private Long pfValue;
    private Long aValue;

    @JsonIgnore
    @ManyToMany(mappedBy = "sources")
    private List<TSEProject> tseProjects;

    @JsonIgnore
    @ManyToMany(mappedBy = "sourceList")
    private List<Architecture> architectures;

    public Source() {
        this.architectures = new ArrayList<>();
        this.tseProjects = new ArrayList<>();
    }

}

@Data
public class LoadDto {
    private Long id;
    private String name;
    private String type;
    private String unity;
    private Long sourcePriority1;
    private Long SourcePriority2;
    private Long SourcePriority3;
    private Long kvaValue;
    private Long kwValue;
    private Long pfValue;
    private Long aValue;
    private Long iccValue;
    private List<Long> tseProjectsId;

    public LoadDto() {
        this.tseProjectsId = new ArrayList<>();
    }

}

@Data
public class SourceDto {

    private Long id;
    private String name;
    private String type;
    private String unity;
    private Long quantity;
    private Long kvaValue;
    private Long kwValue;
    private Long pfValue;
    private Long aValue;

}

Answer 1

我想你需要再排除一些故障。尝试帮助MapStruct并定义一个附加的映射方法，如下所示：

Mapper(componentModel = "spring")
public interface ArchitectureMapper extends EntityMapper<ArchitectureDto, Architecture> {

    @Mapping(source = "loads", target = "loadDtos")
    @Mapping(source = "sources", target = "sourceDtos")
    ArchitectureDto toDto(Architecture architecture);

    // first try with all properties ignored
    // @Mapping( target = "id", ignore = true ) etc.
    SourceDto toDto(Source source);

    // first try with all properties ignored
    // @Mapping( target = "id", ignore = true ) etc.
    LoadDto toDto(Load load);

}

问题是MapStruct试图基于属性名自动映射这些对象。如果它在某个地方发现了相同的名称，它会尝试进行类型转换或使用现有的映射方法来完成它的工作。它甚至尝试了两个步骤（转换，然后是一个方法），这有时会导致这些结果。

您可以提供MapStruct试图自己生成的一些映射，然后再次忽略所有属性，如上面的示例所示。逐个删除忽略行，然后查看MapStruct何时开始抱怨。

像这样的调试有点乏味，但可能在对象图的深处发现了问题。然后，您可以再次删除所有签名，除了解决问题的签名，从而最大限度地利用代码生成。