当DTO中存在相同类型的对象列表时，如何使用ModelMapper

Question

我有以下型号。

组织模式

@Data
@Entity
@Table()
@JsonIdentityInfo( generator = ObjectIdGenerators.PropertyGenerator.class, property = "id" )
public class Organization implements Serializable {
     @Id
     @GeneratedValue( strategy = GenerationType.IDENTITY )
     private Long id;

     private String name;
     .
     .
     .

     @OneToMany( mappedBy = "organization", cascade = CascadeType.MERGE, targetEntity = User.class )
     private Set< User > users;
}

用户模型

@Data
@Entity
@DynamicUpdate
@Table( name = RelationsConstant.TBL_USER_AUTH )
public class User implements Serializable {

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

    private String name;
    .
    .
    .
    @ManyToOne( cascade = CascadeType.MERGE, targetEntity = Organization.class )
    @JoinColumn( nullable = false, foreignKey = @ForeignKey( name = org_usr_fk ) )
    private Organization organization;

    @ManyToMany( fetch = FetchType.EAGER, cascade = CascadeType.MERGE )
    @JoinTable( name = RelationsConstant.TBL_USER_AUTH_ROLE, //
        joinColumns = @JoinColumn( name = "base_user_id", referencedColumnName = "base_user_id", nullable = false ), //
        inverseJoinColumns = @JoinColumn( name = "role_id", referencedColumnName = "id", nullable = false ), //
        uniqueConstraints = { @UniqueConstraint( columnNames = { "base_user_id", "role_id" } ) } )
    private Set< Role > roles;

}

组织DTO

@Data
public class OrganizationDto implements Serializable {
     private Long id;
     private String name;
     private Set<UserDto> users;
}

用户DTO

@Data
public class UserDto implements Serializable {
     private Long id;
     private String name;
     private OrganizationDto organization;
     private Set<RoleDto> roles;
}

当我尝试将这些模型映射到DTO时，我得到以下错误。

处理请求时出错org.modelmapper.MappingException： ModelMapper映射错误：\r\n\r\n1）将组织映射到组织Dto时出错。

下面是我使用的转换器。

public class SetUserToSetUserDtoConverter implements Converter< Set< User >, Set< UserDto > > {

    @Override
    public Set< UserDto > convert( MappingContext< Set< User >, Set< UserDto > > context ) {
        ModelMapper mapper = new ModelMapper( );

        TypeMap< User, UserDto > propertyMapper = mapper.createTypeMap( User.class, UserDto.class );
        propertyMapper.addMappings( mpr -> {
            mpr.skip( User::getOrganization, UserDto::setOrganization );
            mpr.skip( User::getRoles, UserDto::setRoles );
            mpr.skip( User::getPrivileges, UserDto::setPrivileges );
            mpr.skip( User::getPassword, UserDto::setPassword );
        } );

        Set< User > source = context.getSource( );

        return source.stream( ).map( m -> mapper.map( m, UserDto.class ) ).collect( Collectors.toSet( ) );
    }

}

这就是映射器的配置方式。

public List< OrganizationDto > getAll() {
    ModelMapper mapper = new ModelMapper( );
    mapper.getConfiguration( ).setMatchingStrategy( MatchingStrategies.STRICT ).setFieldMatchingEnabled( true ).setFieldAccessLevel( Configuration.AccessLevel.PRIVATE );

    /** With Converter **/
    TypeMap< Organization, OrganizationDto > typeMap = mapper.createTypeMap( Organization.class, OrganizationDto.class );

    typeMap.addMappings( mpr -> mpr.using( new SetUserToSetUserDtoConverter( ) ).map( Organization::getUsers, OrganizationDto::setUsers ) );

    return orgRepo.findAll( ).stream( ).map( m -> mapper.map( m, OrganizationDto.class ) ).collect( Collectors.toList( ) );
}

我发现当我从UserDto类中删除组织字段并从Converter类中删除行mpr.skip（UserDto::setGroup）；时，这个模型映射工作正常。

转换器被定义为将User Object Set转换为UserDto Object Set并跳过组织Dto字段的转换。用户对象和UserDto对象有设置

任何纠正这一点的线索都非常感谢。提前感谢。




Answer 1

而不是我的自定义转换器类（SetUserToSetUserDtoConverter类）中的以下代码，

    TypeMap< UserAuth, UserAuthDto > propertyMapper = mapper.createTypeMap( UserAuth.class, UserAuthDto.class );
    propertyMapper.addMappings( mpr -> {
        mpr.skip( UserAuthDto::setOrganization );
        mpr.skip( UserAuth::getRoles, UserAuthDto::setRoles );
        mpr.skip( UserAuth::getPrivileges, UserAuthDto::setPrivileges );
        mpr.skip( UserAuth::getPassword, UserAuthDto::setPassword );
    } );

我使用下面的代码跳过了组织和不必要的字段以及其他字段。

PropertyMap< UserAuth, UserAuthDto > skipped = new PropertyMap< UserAuth, UserAuthDto >( ) {

                @Override
                protected void configure() {
                    skip( ).setOrganization( null );
                    skip( ).setRoles( null );
                    skip( ).setPrivileges( null );
                    skip( ).setPassword( null );
                }

            };

首先，我怀疑userdt中的组织字段是否会创建循环引用循环之类的东西。但我的跳场逻辑似乎不正确。

问题现已解决。

完全正确的转换器实现如下。

公共类SetUserToSetUserDtoConverter实现转换器

@Override
public Set< UserDto > convert( MappingContext< Set< User >, Set< UserDto > > context ) {
    ModelMapper mapper = new ModelMapper( );
    mapper.getConfiguration( ).setMatchingStrategy( MatchingStrategies.STRICT ).setFieldMatchingEnabled( true );

    PropertyMap< User, UserDto > skipped = new PropertyMap< User, UserDto >( ) {

        @Override
        protected void configure() {
            skip( ).setOrganization( null );
            skip( ).setRoles( null );
            skip( ).setPrivileges( null );
            skip( ).setPassword( null );
        }

    };

    mapper.addMappings( skipped );

    Set< User > source = context.getSource( );

    return source.stream( ).map( m -> mapper.map( m, UserDto.class ) ).collect( Collectors.toSet( ) );
}

}

从艾米·德雷戈里奥（Amy DeGregorio）2018年发布的以下nice博客中获得了想法和参考。https://amydegregorio.com/2018/05/23/skipping-fields-with-modelmapper/