如何在创建新节点之前检查节点是否已存在neo4j

Question

我正在处理一个Spring BootNeo4j应用程序

在保存新密码之前，如何编写自定义密码来检查Priviledge是否存在

UserRole域：@NodeEntity公共类UserRole{

public UserRole(User user, Role role) {
    this.user = user;
    this.role = role;
}

/**
 For Jackson Parsing
 **/
public UserRole() {
}

@GraphId
private Long id;

public UserRole(User user, Role role, Unit unit) {
    this.user = user;
    this.role = role;
    this.unit = unit;
}



public long getId() {
    return id;
}

@Relationship(type = HAS_USERROLE,direction = "OUTGOING")
User user;
public User getUser() {
    return user;
}

@Relationship (type = HAS_ROLE_OF,direction = "OUTGOING")
Role role;
public Role getRole() {
    return role;
}


@Relationship(type = "WORKS_IN",direction = "OUTGOING")
Unit unit;

public Unit getUnit() {
    return unit;
}

public void setUnit(Unit unit) {
    this.unit = unit;
}

@Relationship(type = "HAS_PRIVILEDGE", direction = "OUTGOING")
List<Priviledge> priviledgeList;

public List<Priviledge> getPriviledgeList() {
    return priviledgeList;
}

public void setPriviledgeList(List<Priviledge> priviledgeList) {
    this.priviledgeList = priviledgeList;
}
}

特权域：

public class Priviledge {

@GraphId
Long id;


private String priviledge;

private String priviledgeOn;
private Long priviledgeOnId;

public Priviledge() {
}

public Priviledge(String priviledge, String priviledgeOn) {
    this.priviledge = priviledge;
    this.priviledgeOn = priviledgeOn;
}

public Long getId() {
    return id;
}

public void setId(Long id) {
    this.id = id;
}

public String getPriviledge() {
    return priviledge;
}

public void setPriviledge(String priviledge) {
    this.priviledge = priviledge;
}

public String getPriviledgeOn() {
    return priviledgeOn;
}

public void setPriviledgeOn(String priviledgeOn) {
    this.priviledgeOn = priviledgeOn;
}

public Long getPriviledgeOnId() {
    return priviledgeOnId;
}

  public void setPriviledgeOnId(Long priviledgeOnId) {
    this.priviledgeOnId = priviledgeOnId;
  }
}

Answer 1

在这个问题的答案中可以找到，要更新（而不是创建新实例），在调用save方法时，必须使用节点的ID。

或者（如上述问题的注释所示），您应该基于此文档创建自己的查询。