Spring 数据 Neo4j 父子过滤

Question

我的节点关系如上图

我的类

@NodeEntity
public class User 
{


    @GraphId
    private Long id;

    @Property(name="name")
    private String name;


    @Relationship(type = "CAN_ACCESS", direction = Relationship.OUTGOING)
    private List<Library> libraries;


    // is this necessary ?????
    @Relationship(type = "CAN_ACCESS", direction = Relationship.OUTGOING)
    private List<Book> books;


    public User() 
    {

    }

    // getters
    // setters  
}


@NodeEntity
public class Library 
{
    @GraphId
    private Long id;

    @Property(name="name")
    private String name;


    @Relationship(type = "CONTAINS", direction = Relationship.OUTGOING)
    private List<Book> books;

    // is this necessary ?????
    @Relationship(type = "CAN_ACCESS", direction = Relationship.INCOMING)
    private List<User> users;


    public Library() 
    {

    }

    // getters
    // setters  
}

@NodeEntity
public class Book 
{
    @GraphId
    private Long id;

    @Property(name="name")
    private String name;

    // is this necessary ?????
    @Relationship(type = "CONTAINS", direction = Relationship.INCOMING)
    private Library library;

    // is this necessary ?????
    @Relationship(type = "CAN_ACCESS", direction = Relationship.INCOMING)
    private List<User> users;


    public Book() 
    {

    }

    // getters
    // setters  
}

我有用户节点 ID = 21 和图书馆节点 ID = 32.I 想查询属于图书馆 32 但只有用户 21 可以访问的图书。

注意 - 虽然用户 21 "CAN_ACCESS" 图书馆 32，但这并不意味着他 "CAN_ACCESS" 图书馆 32"CONTAINS" 中的所有图书 "CONTAINS"

我目前的服务方式class是

@Autowired
private LibraryRepository libraryRepository;

@Autowired
private UserRepository userRepository;

@Autowired
private BookRepository bookRepository;

@Autowired
private Session session;


public void testGraph()
{
    Long userId = 21;
    Long libId = 32;
    int depth = 1;

    Library library = libraryRepository.findOne(32,depth);
    List<Book> books = library.getBooks();
    List<Book> userAccessibleBooks = getUserAccessibleBooks(books,userId);
}

public List<Book> getUserAccessibleBooks(List<Book> books,Long userId)
{
    // Loop over book list and get List<User> users;
    // check this user "CAN_ACCESS" the book
    // return accessible book list
}

我认为这不是最好的方法。假设您的图书馆中有数百万本书

有什么解决办法吗？或者我在 Spring 数据 neo4j（过滤器）中遗漏了什么？

总结

我想获取图书馆 32，并将过滤后的图书列表作为子用户 21 "CAN_ACCESS"

Answer 1

您想对此类查询使用存储库查找器。你想要 return List<Book> 所以这将进入 BookRepository。

最简单的方法是定义密码查询：

MATCH (u:User), (l:Library)
WHERE 
ID(u) = {userId} AND ID(u) = {libraryId}
MATCH 
(u)-[:CAN_ACCESS]->(b:Book),
(l)-[:CONTAINS]-(b)
RETURN b

不真正推荐使用原生图形 ID，因此如果您引入例如uuid 查询可能如下所示：

MATCH 
(u:User {uuid:{userUuid}}),
(l:Library {uuid:{libraryUuid}}),
(u)-[:CAN_ACCESS]->(b:Book),
(l)-[:CONTAINS]-(b)
RETURN b

然后将带有此查询的查找器方法添加到 BookRepository 接口中：

@Query("MATCH 
(u:User {uuid:{userUuid}}),
(l:Library {uuid:{libraryUuid}}),
(u)-[:CAN_ACCESS]->(b:Book),
(l)-[:CONTAINS]-(b)
RETURN b")
List<Book> findBooksByUserAndLibrary(@Param("userUuid") String userUuid, @Param("libraryUuid) String libraryUuid);

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