在DBRef对象上使用Spring Data Projection

Question

我开始在使用MongoDB数据库的一个非常简单的项目上学习Spring Data，并且在使用DBRef时遇到了一些麻烦 - 并且可能在如何建模NoSQL db

说明

我的项目应组织与组织者（CD）和一个一对多参加一个简单的竞争。因为人们可以参加多项比赛，所以我为比赛和人员制作了资料库。

完整的代码可以看出在GitHub上：https://github.com/elkjaerit/rest-sample

这是基础类：

public class Competition { 

    @Id private String id; 

    private String name; 

    @DBRef 
    private Person organizer; 

    private List<Participant> participants = new ArrayList<>(); 

} 


public class Participant { 

    private String freq; 

    @DBRef 
    private Person person; 
} 


public class Person { 
    @Id 
    private String id; 

    private String name; 
} 

库：

@RepositoryRestResource(collectionResourceRel = "competition", path = "competition") 
public interface CompetitionRepository extends MongoRepository<Competition, String> { 

} 

@RepositoryRestResource(collectionResourceRel = "person", path = "person") 
public interface PersonRepository extends MongoRepository<Person, String> { 

} 

问题

当我请求竞争资源我没有得到足够的信息参与者 - 只显示“freq”字段。我试过使用@Projection并设法让它为组织者工作，但我不知道如何获取参与者的人员对象？

结果没有投影

{ 
"_links": { 
    "competition": { 
     "href": "http://localhost:8080/competition/5710b32b03641c32671f885a{?projection}", 
     "templated": true 
    }, 
    "organizer": { 
     "href": "http://localhost:8080/competition/5710b32b03641c32671f885a/organizer" 
    }, 
    "self": { 
     "href": "http://localhost:8080/competition/5710b32b03641c32671f885a" 
    } 
}, 
"name": "Competition #1", 
"participants": [ 
    { 
     "freq": "F0" 
    }, 
    { 
     "freq": "F1" 
    }, 
    { 
     "freq": "F2" 
    }, 
    { 
     "freq": "F3" 
    } 
] 
} 

而随着投影

{ 
"_links": { 
    "competition": { 
     "href": "http://localhost:8080/competition/5710b32b03641c32671f885a{?projection}", 
     "templated": true 
    }, 
    "organizer": { 
     "href": "http://localhost:8080/competition/5710b32b03641c32671f885a/organizer" 
    }, 
    "self": { 
     "href": "http://localhost:8080/competition/5710b32b03641c32671f885a" 
    } 
}, 
"name": "Competition #1", 
"organizer": { 
    "name": "Competition organizer" 
}, 
"participants": [ 
    { 
     "freq": "F0" 
    }, 
    { 
     "freq": "F1" 
    }, 
    { 
     "freq": "F2" 
    }, 
    { 
     "freq": "F3" 
    } 
] 
} 

有什么建议？

Answer 1

您可能可以使用SPEL来调用您的相关文档的getter。

您的凸起可以是这个样子 -

@Projection(name = "comp", types = {Competition.class}) 
public interface CompetitionProjection { 

    String getName(); 

    Person getOrganizer(); 

    @Value("#{target.getParticipants()}") 
    List<Participant> getParticipants(); 
}