Question

使用Spring Neo4编写一个带有Spring Neo4j的poc时，我遇到了Bolt驱动程序和Http驱动程序之间似乎不一致的行为。基本上在保存2个节点之间的丰富关系后，测试无法在使用Bolt驱动程序时加载它，但是在尝试使用Http驱动程序时，完全相同的测试成功。

可以从github

下载示例项目

这是一项非常基本/直接的测试，唯一的先决条件是您需要在启用Bolt连接器的情况下安装Neo4j 3。

正如Andrej所建议，请在下面的代码的相关部分找到：

@NodeEntity(label = "Person")
public class Person {
    private Long id;
    private String firstname;
    private String lastname;

    @Relationship(type = "HAS_CONTACT", direction = Relationship.INCOMING)
    private Contact contact;

    // getters and setters here ......... 
}

@NodeEntity(label = "BankAccount")
public class BankAccount {

    private Long id;
    private Integer balance;

    @Relationship(type = "HAS_CONTACT")
    private List<Contact> contacts = new ArrayList<>();

    // getters and setters here ......... 
}

@RelationshipEntity(type = "HAS_CONTACT")
public class Contact {

    public Contact() {
    }

    public Contact(BankAccount bankAccount, Person person) {
        this.bankAccount = bankAccount;
        this.person = person;

        this.bankAccount.getContacts().add(this);
        this.person.setContact(this);
    }

    private Long id;

    @StartNode
    private BankAccount bankAccount;

    @EndNode
    private Person person;

    private String email;
    private String phoneNumber;

    // getters and setters here .........
}

@Repository
public interface ContactRepository extends GraphRepository<Contact> {

    @Query("MATCH (a:BankAccount)-[r:HAS_CONTACT]->(:Person) " +
            "WHERE ID(a)={accountId} " +
            "RETURN r")
    Iterable<Contact> findByAccountId(@Param("accountId") Long accountId);
}

保存1个帐户，1个人和1个人之间的联系关系后，下面的查询是失败的：

Iterable<Contact> contacts = contactRepository.findByAccountId(accountId);

// this assertion will Fail for the BOLT driver, however, it will Succeed for the HTTP driver
// if the accountRepository.findOne(accountId) statement is executed before calling
// contactRepository.findByAccountId(accountId) then the test will also succeed for the BOLT driver
assertThat(size(contacts), is(1));

Answer 1

请参阅以下neo4j小组关于issue：

的回复

无法映射关系实体的原因是因为此查询无法使用开始和结束节点：
 @Query("MATCH (a:BankAccount)-[r:HAS_CONTACT]->(p:Person) " +
            "WHERE ID(a)={accountId} " +
            "RETURN r,")
    Iterable<Contact> findByAccountId(@Param("accountId") Long accountId);
您需要返回这些节点才能构造有效的节点关系实体，像这样：
 @Query("MATCH (a:BankAccount)-[r:HAS_CONTACT]->(p:Person) " +
            "WHERE ID(a)={accountId} " +
            "RETURN r,a,p")
    Iterable<Contact> findByAccountId(@Param("accountId") Long accountId);
HTTP端点的副作用是允许它传递无论如何，此端点都会返回开始和结束节点。请参阅 http://graphaware.com/neo4j/2016/04/06/mapping-query-entities-sdn.html 了解更多信息。

Spring Neo4j - Bolt驱动程序无法加载关系，而Http驱动程序成功完成

1 个答案: