Neo4j OGM无法在保存时清除空值关系

编程问答 2022-10-31

问题描述

  • Neo4j社区4.0.3
  • Windows 10
    • 通过Java 11 OGM框架访问的
  • 螺栓驱动程序
  • 复制步骤...

我已经在下面创建了两个（helm package --dependency-update parent-chart 和Car）类，然后运行第三个（Person）类作为JUnit测试。我原以为最终的assertNull会通过，但是失败了：已经设置，保存，然后清除并再次保存的关系似乎并没有在最终保存中保留其清除/空值处理。

这对我来说似乎很奇怪，所以我想知道这是否是一个错误...但是接受它很可能是我所缺乏的知识。

（我想知道是否需要创建一个显式的关系类，然后使用其标识符将其删除，但是鉴于我可能不想要其他任何属性，我宁愿不要来。）

任何人都可以向我提供这方面的理解将是非常欢迎的。谢谢！

PocTest
import org.neo4j.ogm.annotation.GeneratedValue;
import org.neo4j.ogm.annotation.Id;
import org.neo4j.ogm.annotation.NodeEntity;
import org.neo4j.ogm.annotation.Relationship;

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

  @GeneratedValue
  @Id
  private Long id;

  @Relationship( type = "DRIVER",direction = Relationship.OUTGOING )
  private Person driver;

  public Long getId()
  {
    return this.id;
  }

  public Person getDriver()
  {
    return this.driver;
  }

  public void setDriver( final Person driver )
  {
    this.driver = driver;
  }
}

import org.neo4j.ogm.annotation.Id;
import org.neo4j.ogm.annotation.NodeEntity;

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

  @Id
  private String name;

  public String getName()
  {
    return this.name;
  }

  public void setName( final String name )
  {
    this.name = name;
  }
}

解决方法

完整的解决方法“解决方案”，来自我上面的评论：


import org.neo4j.ogm.annotation.GeneratedValue;
import org.neo4j.ogm.annotation.Id;
import org.neo4j.ogm.annotation.NodeEntity;
import org.neo4j.ogm.annotation.Relationship;

import com.fasterxml.jackson.annotation.JsonIgnoreProperties;

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

  @GeneratedValue
  @Id
  private Long id;

  @JsonIgnoreProperties( { "car" } )
  @Relationship( type = "DRIVEN_BY",direction = Relationship.OUTGOING )
  private CarDriver drivenBy;

  public Long getId()
  {
    return this.id;
  }

  public CarDriver getDrivenBy()
  {
    return this.drivenBy;
  }

  public void setDrivenBy( final CarDriver value )
  {
    if( this.drivenBy != null && this.drivenBy.getCar() != this )
    {
      this.drivenBy.setCar( null );
    }
    this.drivenBy = value;
    if( this.drivenBy != null && this.drivenBy.getCar() != this )
    {
      this.drivenBy.setCar( this );
    }
  }
}

import org.neo4j.ogm.annotation.Id;
import org.neo4j.ogm.annotation.NodeEntity;
import org.neo4j.ogm.annotation.Relationship;

import com.fasterxml.jackson.annotation.JsonIgnoreProperties;

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

  @Id
  private String name;

  @JsonIgnoreProperties( { "drivenBy" } )
  @Relationship( type = "DRIVEN_BY",direction = Relationship.INCOMING )
  private CarDriver drives;

  public String getName()
  {
    return this.name;
  }

  public void setName( final String name )
  {
    this.name = name;
  }

  public CarDriver getDrives()
  {
    return this.drives;
  }

  public void setDrives( final CarDriver value )
  {
    if( this.drives != null && this.drives.getDriver() != this )
    {
      this.drives.setDriver( null );
    }
    this.drives = value;
    if( this.drives != null && this.drives.getDriver() != this )
    {
      this.drives.setDriver( this );
    }
  }
}

import org.neo4j.ogm.annotation.EndNode;
import org.neo4j.ogm.annotation.GeneratedValue;
import org.neo4j.ogm.annotation.Id;
import org.neo4j.ogm.annotation.RelationshipEntity;
import org.neo4j.ogm.annotation.StartNode;

import com.fasterxml.jackson.annotation.JsonIgnoreProperties;

@RelationshipEntity( type = "DRIVEN_BY" )
public class CarDriver {
  @GeneratedValue
  @Id
  private Long id;
  @JsonIgnoreProperties( "drivenBy" )
  @StartNode
  private Car car;
  @JsonIgnoreProperties( "drives" )
  @EndNode
  private Person driver;

  public Long getId()
  {
    return this.id;
  }

  public Car getCar()
  {
    return this.car;
  }

  public void setCar( final Car car )
  {
    if( this.car != null && this.car.getDrivenBy() != this )
    {
      this.car.setDrivenBy( null );
    }
    this.car = car;
    if( this.car != null && car.getDrivenBy() != this )
    {
      car.setDrivenBy( this );
    }
  }

  public Person getDriver()
  {
    return this.driver;
  }

  public void setDriver( final Person driver )
  {
    if( this.driver != null && this.driver.getDrives() != this )
    {
      this.driver.setDrives( null );
    }
    this.driver = driver;
    if( this.driver != null && driver.getDrives() != this )
    {
      driver.setDrives( this );
    }
  }
}

import static org.junit.jupiter.api.Assertions.assertNull;

import org.junit.jupiter.api.BeforeAll;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import org.neo4j.ogm.config.Configuration;
import org.neo4j.ogm.session.Session;
import org.neo4j.ogm.session.SessionFactory;
import org.springframework.util.StringUtils;

public class PoCTest {

  private static SessionFactory ogmSessionFactory;

  @BeforeAll
  private static void createSessionFactory()
  {
    final Configuration config = new Configuration.Builder().uri( "bolt://localhost:7687" )
          .credentials( "neo4j",StringUtils.replace( "111","1","n304j" ) )
          .useNativeTypes()
          .verifyConnection( true )
          .build();
    ogmSessionFactory = new SessionFactory( config,PoCTest.class.getPackageName() );
  }

  private static Session getOgmSession()
  {
    return ogmSessionFactory.openSession();
  }

  @BeforeEach
  void setUp()
  {
    getOgmSession().deleteAll( CarDriver.class );
    getOgmSession().deleteAll( Car.class );
    getOgmSession().deleteAll( Person.class );
  }

  @Test
  void testCreateCarChangeDriver()
  {
    final Car car = new Car();
    final Person fred = new Person();
    fred.setName( "fred" );
    final CarDriver carDriver = new CarDriver();
    carDriver.setCar( car );
    carDriver.setDriver( fred );
    getOgmSession().save( car );
    getOgmSession().delete( carDriver );
    assertNull( getOgmSession().load( Car.class,car.getId() ).getDrivenBy() );
    assertNull( getOgmSession().load( Person.class,fred.getName() ).getDrives() );
  }
}
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