Question

使用spring-data-neo4j，我无法在具有相同标签的同一个类中设置两个关系属性。

以下代码可以在我的分支https://github.com/spencerhrob/gs-accessing-data-neo4j/tree/same-name-relationships中找到。

Person.java：

@NodeEntity
public class Person {

    @GraphId Long id;
    public String name;

    public Person() {}
    public Person(String name) { this.name = name; }

    @RelatedTo(type="MEMBER_OF", direction=Direction.OUTGOING)
    Dojo dojo;

    @RelatedTo(type="MEMBER_OF", direction=Direction.OUTGOING)
    MailingList mailingList;

    public void setDojo(Dojo dojo) {
        this.dojo = dojo;
    }
    public void setMailingList(MailingList mailingList) {
        this.mailingList = mailingList;
    }

    @Override
    public String toString() {
        return "Person [name=" + name + "]";
    }
}

Dojo.java：

@NodeEntity
public class Dojo {

    @GraphId Long id;
    public String name;

    public Dojo() { }
    public Dojo(String name) { this.name = name; }

    @Override
    public String toString() {
        return "Dojo [name=" + name + "]";
    }
}

MailingList.java：

@NodeEntity
public class MailingList {

    @GraphId Long id;
    public String name;

    public MailingList() { }
    public MailingList(String name) { this.name = name; }

    @Override
    public String toString() {
        return "MailingList [name=" + name + "]";
    }

}

Application.java：

@Configuration
@EnableNeo4jRepositories(basePackages = "hello")
public class Application extends Neo4jConfiguration implements CommandLineRunner {

    public Application() {
        setBasePackage("hello");
    }

    @Bean
    GraphDatabaseService graphDatabaseService() {
        return new GraphDatabaseFactory().newEmbeddedDatabase("accessingdataneo4j.db");
    }

    @Autowired
    PersonRepository personRepository;

    @Autowired
    GraphDatabase graphDatabase;

    public void run(String... args) throws Exception {
        Transaction tx = graphDatabase.beginTx();
        try {
            Person linus = new Person("Linus");
            linus.setDojo(new Dojo("Coding Dojo"));
            linus.setMailingList(new MailingList("Kernel Mailing List"));

            personRepository.save(linus);

            tx.success();
        } finally {
            tx.close();
        }
    }

    public static void main(String[] args) throws Exception {
        FileUtils.deleteRecursively(new File("accessingdataneo4j.db"));

        SpringApplication.run(Application.class, args);
    }
}

当我运行此代码时，我得到以下异常：

java.lang.IllegalStateException：无法执行CommandLineRunner 在 org.springframework.boot.SpringApplication.runCommandLineRunners（SpringApplication.java:680）在 org.springframework.boot.SpringApplication.afterRefresh（SpringApplication.java:695）在 org.springframework.boot.SpringApplication.run（SpringApplication.java:321）在 org.springframework.boot.SpringApplication.run（SpringApplication.java:952）在 org.springframework.boot.SpringApplication.run（SpringApplication.java:941） at hello.Application.main（Application.java:56）引起： org.springframework.data.mapping.model.MappingException：设置属性mailingList到Person [name = Linus] at的Dojo [name = null] org.springframework.data.neo4j.support.mapping.SourceStateTransmitter.setProperty（SourceStateTransmitter.java:85）在 org.springframework.data.neo4j.support.mapping.SourceStateTransmitter.copyEntityStatePropertyValue（SourceStateTransmitter.java:91）在 org.springframework.data.neo4j.support.mapping.SourceStateTransmitter.access $ 000（SourceStateTransmitter.java:40）在 org.springframework.data.neo4j.support.mapping.SourceStateTransmitter $ 2.doWithAssociation（SourceStateTransmitter.java:61）在 org.springframework.data.mapping.model.BasicPersistentEntity.doWithAssociations（BasicPersistentEntity.java:324）在 org.springframework.data.neo4j.support.mapping.SourceStateTransmitter.copyPropertiesFrom（SourceStateTransmitter.java:57）在 org.springframework.data.neo4j.support.mapping.Neo4jEntityConverterImpl.loadEntity（Neo4jEntityConverterImpl.java:112）在 org.springframework.data.neo4j.support.mapping.Neo4jEntityConverterImpl.read（Neo4jEntityConverterImpl.java:104）在 org.springframework.data.neo4j.support.mapping.Neo4jEntityPersister $ CachedConverter.read（Neo4jEntityPersister.java:170）在 org.springframework.data.neo4j.support.mapping.Neo4jEntityPersister.createEntityFromState（Neo4jEntityPersister.java:189）在 org.springframework.data.neo4j.support.mapping.Neo4jEntityPersister.persist（Neo4jEntityPersister.java:244）在 org.springframework.data.neo4j.support.mapping.Neo4jEntityPersister.persist（Neo4jEntityPersister.java:231）在 org.springframework.data.neo4j.support.Neo4jTemplate.save（Neo4jTemplate.java:356）在 org.springframework.data.neo4j.support.Neo4jTemplate.save（Neo4jTemplate.java:350）在 org.springframework.data.neo4j.repository.AbstractGraphRepository.save（AbstractGraphRepository.java:91） at sun.reflect.NativeMethodAccessorImpl.invoke0（Native Method）at sun.reflect.NativeMethodAccessorImpl.invoke（NativeMethodAccessorImpl.java:57）在 sun.reflect.DelegatingMethodAccessorImpl.invoke（DelegatingMethodAccessorImpl.java:43）在java.lang.reflect.Method.invoke（Method.java:606）at org.springframework.data.repository.core.support.RepositoryFactorySupport $ QueryExecutorMethodInterceptor.executeMethodOn（RepositoryFactorySupport.java:405）在 org.springframework.data.repository.core.support.RepositoryFactorySupport $ QueryExecutorMethodInterceptor.doInvoke（RepositoryFactorySupport.java:390）在 org.springframework.data.repository.core.support.RepositoryFactorySupport $ QueryExecutorMethodInterceptor.invoke（RepositoryFactorySupport.java:344）在 org.springframework.aop.framework.ReflectiveMethodInvocation.proceed（ReflectiveMethodInvocation.java:179）在 org.springframework.transaction.interceptor.TransactionInterceptor $ 1.proceedWithInvocation（TransactionInterceptor.java:98）在 org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction（TransactionAspectSupport.java:262）在 org.springframework.transaction.interceptor.TransactionInterceptor.invoke（TransactionInterceptor.java:95）在 org.springframework.aop.framework.ReflectiveMethodInvocation.proceed（ReflectiveMethodInvocation.java:179）在 org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke（PersistenceExceptionTranslationInterceptor.java:136）在 org.springframework.aop.framework.ReflectiveMethodInvocation.proceed（ReflectiveMethodInvocation.java:179）在 org.springframework.aop.framework.JdkDynamicAopProxy.invoke（JdkDynamicAopProxy.java:207）在com.sun.proxy。$ Proxy43.save（未知来源）at hello.Application.run（Application.java:44）at org.springframework.boot.SpringApplication.runCommandLineRunners（SpringApplication.java:677） ...省略了5个常见帧引起的： org.springframework.core.convert.ConverterNotFoundException：没有转换器发现能够从类型hello.Dojo转换为类型 hello.MailingList at org.springframework.core.convert.support.GenericConversionService.handleConverterNotFound（GenericConversionService.java:291）在 org.springframework.core.convert.support.GenericConversionService.convert（GenericConversionService.java:177）在 org.springframework.core.convert.support.GenericConversionService.convert（GenericConversionService.java:158）在 org.springframework.data.mapping.model.BeanWrapper.getPotentiallyConvertedValue（BeanWrapper.java:155）在 org.springframework.data.mapping.model.BeanWrapper.setProperty（BeanWrapper.java:75）在 org.springframework.data.neo4j.support.mapping.SourceStateTransmitter.setProperty（SourceStateTransmitter.java:83） ...省略了37个常见帧

那里有很多，但真正的错误是Spring试图将Dojo转换为MailingList。

同时，如果我用不同的名称命名关系（如在我的分支https://github.com/spencerhrob/gs-accessing-data-neo4j/tree/different-name-relationships中），则此代码有效。 Person.java：

@NodeEntity
public class Person {

    @GraphId Long id;
    public String name;

    public Person() {}
    public Person(String name) { this.name = name; }

    @RelatedTo(type="MEMBER_OF_DOJO", direction=Direction.OUTGOING)
    Dojo dojo;

    @RelatedTo(type="MEMBER_OF_LIST", direction=Direction.OUTGOING)
    MailingList mailingList;

    public void setDojo(Dojo dojo) {
        this.dojo = dojo;
    }
    public void setMailingList(MailingList mailingList) {
        this.mailingList = mailingList;
    }

    @Override
    public String toString() {
        return "Person [name=" + name + "]";
    }
}

对Application.java（或Dojo.java或MailingList.java）没有任何更改，此代码成功执行。

我从这个例子中理解，spring-data-neo4j不允许类具有两个具有相同标签的属性。在某些情况下，不同的关系需要具有相同的标签 - 例如，符合建模标准。是否可以在spring-data-neo4j中设置多个具有相同名称的关系？如果是这样，怎么样？

Answer 1

我找到了这个问题的答案。我所寻找的是“enforceTargetType”属性described in the documentation。

我已经使用此修复程序创建了一个存储库的分支。它位于https://github.com/spencerhrob/gs-accessing-data-neo4j/tree/same-name-enforce-target。

Person.java：

@NodeEntity
public class Person {

    @GraphId Long id;
    public String name;

    public Person() {}
    public Person(String name) { this.name = name; }

    @RelatedTo(type="MEMBER_OF", direction=Direction.OUTGOING, enforceTargetType=true)
    Dojo dojo;

    @RelatedTo(type="MEMBER_OF", direction=Direction.OUTGOING, enforceTargetType=true)
    MailingList mailingList;

    public void setDojo(Dojo dojo) {
        this.dojo = dojo;
    }
    public void setMailingList(MailingList mailingList) {
        this.mailingList = mailingList;
    }

    @Override
    public String toString() {
        return "Person [name=" + name + "]";
    }
}

在没有对存储库进行其他更改的情况下，此代码运行时没有任何错误，并且检查创建的Neo4j数据库显示它的行为符合预期。

spring-data-neo4j：无法使用相同的标签创建两个关系属性

1 个答案: