如何返回关系属性(Neo4j + Spring数据)？
如何返回关系属性(Neo4j + Spring数据)？
提问于 2021-01-11 15:22:17
项目细节
我正在使用Kotlin跟踪这些文档弹簧数据Neo4j，并且很难从存储库查询中返回关系：
数据库布局
我有一个User节点和一个具有以下关系的Skill节点：
实体
技能
@Node
data class Skill(
@Id
val uid: UUID,
val title: String,
) {
constructor(title: String) : this(UidGenerator.makeOne(), title)
}用户
@Node
data class User(
@Id
var uid: UUID,
@Relationship(type = "DEMONSTRATES")
val demonstrates: List<Demonstrates>,
val firstName: String,
val lastName: String,
) {
constructor(demonstrates: List<Demonstrates>, firstName: String, lastName: String)
: this(UidGenerator.makeOne(), demonstrates, firstName, lastName)
}关系属性
@RelationshipProperties
data class Demonstrates(
@TargetNode
val skill: Skill,
val rating: Int,
)我遇到的问题
当我注入下面的存储库并调用getDemonstrationList时，我将得到下面的错误。
@Repository
interface MyRepository : Neo4jRepository<Skill, UUID> {
@Query("""
MATCH (:User)-[d:DEMONSTRATES]->(:Skill) RETURN d
""")
fun getDemonstrationList(): List<Demonstrates>
}Caused by: org.springframework.data.neo4j.core.mapping.NoRootNodeMappingException: Could not find mappable nodes or relationships inside Record<{d: relationship<4>}> for org.springframework.data.neo4j.core.mapping.DefaultNeo4jPersistentEntity@750a04ec
at org.springframework.data.neo4j.core.mapping.DefaultNeo4jEntityConverter.read(DefaultNeo4jEntityConverter.java:106) ~[spring-data-neo4j-6.0.2.jar:6.0.2]
at org.springframework.data.neo4j.core.mapping.DefaultNeo4jEntityConverter.read(DefaultNeo4jEntityConverter.java:67) ~[spring-data-neo4j-6.0.2.jar:6.0.2]
at org.springframework.data.neo4j.core.mapping.Schema.lambda$getRequiredMappingFunctionFor$0(Schema.java:96) ~[spring-data-neo4j-6.0.2.jar:6.0.2]
at org.springframework.data.neo4j.repository.query.Neo4jQuerySupport.lambda$getMappingFunction$0(Neo4jQuerySupport.java:105) ~[spring-data-neo4j-6.0.2.jar:6.0.2]
at org.springframework.data.neo4j.core.PreparedQuery$AggregatingMappingFunction.apply(PreparedQuery.java:218) ~[spring-data-neo4j-6.0.2.jar:6.0.2]
at org.springframework.data.neo4j.core.PreparedQuery$AggregatingMappingFunction.apply(PreparedQuery.java:154) ~[spring-data-neo4j-6.0.2.jar:6.0.2]
at org.springframework.data.neo4j.core.DelegatingMappingFunctionWithNullCheck.apply(DelegatingMappingFunctionWithNullCheck.java:45) ~[spring-data-neo4j-6.0.2.jar:6.0.2]
at org.springframework.data.neo4j.core.DelegatingMappingFunctionWithNullCheck.apply(DelegatingMappingFunctionWithNullCheck.java:35) ~[spring-data-neo4j-6.0.2.jar:6.0.2]
at org.springframework.data.neo4j.core.DefaultNeo4jClient$DefaultRecordFetchSpec.lambda$partialMappingFunction$0(DefaultNeo4jClient.java:325) ~[spring-data-neo4j-6.0.2.jar:6.0.2]
at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:195) ~[na:na]
at java.base/java.util.Iterator.forEachRemaining(Iterator.java:133) ~[na:na]
at java.base/java.util.Spliterators$IteratorSpliterator.forEachRemaining(Spliterators.java:1801) ~[na:na]
at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484) ~[na:na]
at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474) ~[na:na]
at java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:913) ~[na:na]
at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) ~[na:na]
at java.base/java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:578) ~[na:na]
at org.springframework.data.neo4j.core.DefaultNeo4jClient$DefaultRecordFetchSpec.all(DefaultNeo4jClient.java:312) ~[spring-data-neo4j-6.0.2.jar:6.0.2]
at org.springframework.data.neo4j.core.Neo4jTemplate$DefaultExecutableQuery.getResults(Neo4jTemplate.java:575) ~[spring-data-neo4j-6.0.2.jar:6.0.2]
at org.springframework.data.neo4j.repository.query.Neo4jQueryExecution$DefaultQueryExecution.execute(Neo4jQueryExecution.java:51) ~[spring-data-neo4j-6.0.2.jar:6.0.2]
at org.springframework.data.neo4j.repository.query.AbstractNeo4jQuery.execute(AbstractNeo4jQuery.java:85) ~[spring-data-neo4j-6.0.2.jar:6.0.2]
at org.springframework.data.repository.core.support.RepositoryMethodInvoker.doInvoke(RepositoryMethodInvoker.java:137) ~[spring-data-commons-2.4.2.jar:2.4.2]
at org.springframework.data.repository.core.support.RepositoryMethodInvoker.invoke(RepositoryMethodInvoker.java:121) ~[spring-data-commons-2.4.2.jar:2.4.2]
at org.springframework.data.repository.core.support.QueryExecutorMethodInterceptor.doInvoke(QueryExecutorMethodInterceptor.java:152) ~[spring-data-commons-2.4.2.jar:2.4.2]
at org.springframework.data.repository.core.support.QueryExecutorMethodInterceptor.invoke(QueryExecutorMethodInterceptor.java:131) ~[spring-data-commons-2.4.2.jar:2.4.2]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.3.2.jar:5.3.2]
at org.springframework.data.projection.DefaultMethodInvokingMethodInterceptor.invoke(DefaultMethodInvokingMethodInterceptor.java:80) ~[spring-data-commons-2.4.2.jar:2.4.2]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.3.2.jar:5.3.2]
at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:123) ~[spring-tx-5.3.2.jar:5.3.2]
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:388) ~[spring-tx-5.3.2.jar:5.3.2]
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:119) ~[spring-tx-5.3.2.jar:5.3.2]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.3.2.jar:5.3.2]
at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:137) ~[spring-tx-5.3.2.jar:5.3.2]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.3.2.jar:5.3.2]
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:97) ~[spring-aop-5.3.2.jar:5.3.2]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.3.2.jar:5.3.2]
at org.springframework.data.repository.core.support.MethodInvocationValidator.invoke(MethodInvocationValidator.java:98) ~[spring-data-commons-2.4.2.jar:2.4.2]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.3.2.jar:5.3.2]
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:215) ~[spring-aop-5.3.2.jar:5.3.2]
at com.sun.proxy.$Proxy68.getDemonstrationIds(Unknown Source) ~[na:na]
at com.ntr.neo4j.Neo4jApplication.run(Neo4jApplication.kt:44) ~[classes/:na]
at org.springframework.boot.SpringApplication.callRunner(SpringApplication.java:804) ~[spring-boot-2.4.1.jar:2.4.1]
... 5 common frames omitted我的问题
我对Kotlin和Neo4j非常陌生，但我确实理解Spring框架。据我所知，存储库无法解决它需要从查询结果中创建Demonstrates实例列表的问题。我感兴趣的是摆脱这种关系的rating属性，但对于如何做到这一点，本教程并不十分清楚。请让我知道我遗漏了什么，以便让我的查询返回一个Demonstrates列表
回答 2
Stack Overflow用户
回答已采纳
发布于 2021-01-11 19:33:29
从Spring Neo4j 6开始，关系不再是顶级实体了.
因此，存储库方法必须返回Skill、SomeCollection<Skill> (其中SomeCollection可以是List、Set、Flux、Page等)。您还可以基于Skill返回投影，但不能返回@RelationshipProperties-annotated类。
Stack Overflow用户
发布于 2022-08-30 11:01:29
到目前为止，使用Spring-Boot2.7.3与Java、Neo4J和Webflux启动器一起使用Spring-Boot2.7.3(使用正确注释的领域类型)对我来说是可行的。不过，我没有用非反应性的起动器试过这个。
public interface YourRelationDomainTypeRepository extends ReactiveNeo4jRepository<YourRelationDomainType, Long> {
@Query("MATCH (u:NodeLabel1 {name: $userName})-[r:Relation]->(m:NodeLabel2) RETURN properties(r)")
Flux<YourRelationDomainType> findPropertiesByUserName(@Param("userName") String userName);
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/65669613
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