Neo4j TimeTree REST API上一导航和下一导航

时间：2015-05-22 12:38:46

标签： neo4j graph-databases spring-data-neo4j-4 graphaware

我目前正在使用Neo4j TimeTree REST API，有没有办法导航到给定时间戳之前和之后的时间？我的决议是第二，我只是意识到，如果分钟发生了变化，那么就没有“下一步”。关系将前一分钟的前一秒连接到当前的第二分钟。这使得密码查询非常复杂，如果它已经可用，我只是不想再次重新发明轮子。 在此先感谢您的回复，我们非常感谢！

修改

我必须再次重现丢失的NEXT关系问题，如下图所示。这是从我第三次添加新的第二次瞬间开始发生的。

enter image description here

我实际创建了一个NodeEntity来操作第二个节点。课程如下。

@NodeEntity(label = "Second")
public class TimeTreeSecond {
    @GraphId
    private Long id;

    private Integer value;

    @Relationship(type = "CREATED_ON", direction = Relationship.INCOMING)
    private FilterVersionChange relatedFilterVersionChange;

    @Relationship(type = "NEXT", direction = Relationship.OUTGOING)
    private TimeTreeSecond nextTimeTreeSecond;

    @Relationship(type = "NEXT", direction = Relationship.INCOMING)
    private TimeTreeSecond prevTimeTreeSecond;

    public TimeTreeSecond() {
    }

    public Long getId() {
        return id;
    }

    public void next(TimeTreeSecond nextTimeTreeSecond) {
        this.nextTimeTreeSecond = nextTimeTreeSecond;
    }

    public FilterVersionChange getRelatedFilterVersionChange() {
        return relatedFilterVersionChange;
    }
}

这里的问题是Incoming NEXT关系。当我省略它时，一切正常。 有时候，当我在短时间内重复创建时间时，我甚至会在控制台中遇到这种异常。

Exception in thread "main" org.neo4j.ogm.session.result.ResultProcessingException: Could not initialise response
    at org.neo4j.ogm.session.response.GraphModelResponse.<init>(GraphModelResponse.java:38)
    at org.neo4j.ogm.session.request.SessionRequestHandler.execute(SessionRequestHandler.java:55)
    at org.neo4j.ogm.session.Neo4jSession.load(Neo4jSession.java:108)
    at org.neo4j.ogm.session.Neo4jSession.load(Neo4jSession.java:100)
    at org.springframework.data.neo4j.repository.GraphRepositoryImpl.findOne(GraphRepositoryImpl.java:50)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.executeMethodOn(RepositoryFactorySupport.java:452)
    at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.doInvoke(RepositoryFactorySupport.java:437)
    at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.invoke(RepositoryFactorySupport.java:409)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:99)
    at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:281)
    at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:136)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:207)
    at com.sun.proxy.$Proxy32.findOne(Unknown Source)
    at de.rwthaachen.service.core.FilterDefinitionServiceImpl.createNewFilterVersionChange(FilterDefinitionServiceImpl.java:100)
    at sampleapp.FilterLauncher.main(FilterLauncher.java:50)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:140)
Caused by: org.neo4j.ogm.session.result.ResultProcessingException: "errors":[{"code":"Neo.ClientError.Statement.InvalidType","message":"Expected a numeric value for empty iterator, but got null"}]}
    at org.neo4j.ogm.session.response.JsonResponse.parseErrors(JsonResponse.java:128)
    at org.neo4j.ogm.session.response.JsonResponse.parseColumns(JsonResponse.java:102)
    at org.neo4j.ogm.session.response.JsonResponse.initialiseScan(JsonResponse.java:46)
    at org.neo4j.ogm.session.response.GraphModelResponse.initialiseScan(GraphModelResponse.java:66)
    at org.neo4j.ogm.session.response.GraphModelResponse.<init>(GraphModelResponse.java:36)
    ... 27 more
2015-05-23 01:30:46,204  INFO ork.data.neo4j.config.Neo4jConfiguration:  62 - Intercepted exception

下面是一个用于创建临时节点的REST调用示例： http://localhost:7474/graphaware/timetree/1202/single/1432337658713?resolution=Second&timezone=Europe/Amsterdam

我用来创建数据的方法：

public FilterVersionChange createNewFilterVersionChange(String projectName,
                                                            String filterVersionName,
                                                            String filterVersionChangeDescription,
                                                            Set<FilterState> filterStates)
    {
        Long filterVersionNodeId = filterVersionRepository.findFilterVersionByName(projectName, filterVersionName);
        FilterVersion newFilterVersion = filterVersionRepository.findOne(filterVersionNodeId, 2);

        // Populate all the existing filters in the current project
        Map<String, Filter> existingFilters = new HashMap<String, Filter>();
        try
        {
            for(Filter filter : newFilterVersion.getProject().getFilters())
            {
                existingFilters.put(filter.getMatchingString(), filter);
            }
        }
        catch(Exception e) {}

        // Map the filter states to the populated filters, if any. Otherwise, create new filter for it.
        for(FilterState filterState : filterStates)
        {
            Filter filter = existingFilters.get(filterState.getMatchingString());
            if(filter == null)
            {
                filter = new Filter(filterState.getMatchingString(), filterState.getMatchingType(), newFilterVersion.getProject());
            }
            filterState.stateOf(filter);
        }

        Long now = System.currentTimeMillis();
        TimeTreeSecond timeInstantNode = timeTreeSecondRepository.findOne(timeTreeService.getFilterTimeInstantNodeId(projectName, now));
        FilterVersionChange filterVersionChange = new FilterVersionChange(filterVersionChangeDescription, now, filterStates, filterStates, newFilterVersion, timeInstantNode);
        FilterVersionChange addedFilterVersionChange = filterVersionChangeRepository.save(filterVersionChange);

        return addedFilterVersionChange;
    }

2 个答案:

答案 0 :(得分：4)

秒数通过NEXT关系相互链接，即使在几分钟内也是如此。

希望这就是你的意思 enter image description here

答案 1 :(得分：3)

暂时搁置一下TimeTree的具体用法，我想描述一下如何使用SDN 4来管理双向链表，特别是对于底层图在节点之间使用单一关系类型的情况，例如

(post:Post)-[:NEXT]->(post:Post)

你不能做什么

由于映射框架的限制，无法在对象模型中的两个不同方向上可靠地声明两次相同的关系类型，即此（当前）不起作用：

class Post {
   @Relationship(type="NEXT", direction=Relationship.OUTGOING)
   Post next;

   @Relationship(type="NEXT", direction=Relationship.INCOMING)
   Post previous;
}

你能做什么

相反，我们可以将@Transient注释与使用带注释的setter方法结合起来，以获得所需的结果：

class Post {
   Post next;

   @Transient Post previous;

   @Relationship(type="NEXT", direction=Relationship.OUTGOING)
   public void setNext(Post next) {
      this.next = next;
      if (next != null) {
          next.previous = this;
      }
   }
}

最后一点，如果您希望能够从任何起始帖子向前和向后浏览帖子的整个列表而无需从数据库中不断重新获取它们，则可以将获取深度设置为-1你加载帖子，例如：

findOne(post.getId(), -1);

请记住，无限深度查询将从匹配的对象中获取图中的每个可到达对象，因此请小心使用它！

希望这是有帮助的

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