Spring Boot Neo4J 没有 propertyKey="__type__" 的属性

Question

我正在使用 spring boot 1.2.3.RELEAE 和 spring-data-neo4j 3.2.2.RELEASE，它们使用 Neo4J 2.1.5。

我正在尝试构建一个通过“CONNECTED_TO”关系连接到其他站点的站点图。该关系具有“距离”作为属性。稍后我们计划在图上做 dijkstra 算法。但无论如何......这就是我们所拥有的：

@NodeEntity
@TypeAlias("Station")
public class Station {

    @GraphId
    private Long id;

    @Indexed
    public String name;

    @Indexed(unique = true)
    public String tlc;

    public double gps_x;
    public double gps_y;

    @RelatedTo(type = "CONNECTED_TO", direction = OUTGOING)
    public Set<Station> connectedTo = new HashSet<>();

    @Fetch
    @RelatedToVia(type = "CONNECTED_TO", direction = OUTGOING)
    public Set<ConnectedTo> connections = new HashSet<>();

    // getter + setters
}

@RelationshipEntity(type = "CONNECTED_TO")
public class ConnectedTo {

    @GraphId
    private Long id;

    @Fetch
    @StartNode
    private Station fromStation;

    @Fetch
    @EndNode
    private Station toStation;

    private double distance;

    // getter + setters
}

还有一个包含 2K 多个站点的stations.csv……这是一个示例：

name,tlc,gps_y,gps_x
Alexandra Palace,AAP,-0.120235219,51.59792231
Achanalt,AAT,-4.913851155,57.60959445
Aberdare,ABA,-3.443083402,51.71505622
Altnabreac,ABC,-3.706280166,58.38814697

然后对于关系船（5K 以上），我们有 station_connections.csv.. 这是一个示例：

name,from_tlc,to_tlc,distance
Alexandra Palace,AAP,BOP,0.7
Alexandra Palace,AAP,HRN,0.9
Alexandra Palace,AAP,NSG,1.5
Achanalt,AAT,ACN,6.5
Achanalt,AAT,LCC,4.2
Aberdare,ABA,CMH,0.8
Altnabreac,ABC,FRS,8.1
Altnabreac,ABC,SCT,9.1

然后我有一个导入服务来导入 CSV

首先，我从stations.csv 导入电台。这工作正常。这是导入它的代码：

@Transactional
public void importStations(CsvReader stationsFile) throws IOException {
    // id,terminalName,name,installed,locked,temporary,lat,lng
    while (stationsFile.readRecord()) {

        Station station = new Station()
                .setName(stationsFile.get("name").toUpperCase())
                .setTlc(stationsFile.get("tlc").toUpperCase())
                .setGps_y(asDouble(stationsFile.get("gps_y")))
                .setGps_x(asDouble(stationsFile.get("gps_x")));

        stationRepository.save(station);
    }
}

其次，我想从 station_connections.csv 导入站连接。使用以下代码：

@Transactional
public void importConnections(CsvReader stationsFile) throws IOException {
        // name,from_tlc,to_tlc,distance

        while (stationsFile.readRecord()) {

            String from_tlc = stationsFile.get("from_tlc").toUpperCase();
            String to_tlc = stationsFile.get("to_tlc").toUpperCase();
            String distance = stationsFile.get("distance");

            Station fromStation = stationRepository.findByTlc(from_tlc);
            Station toStation = stationRepository.findByTlc(to_tlc);

            if (fromStation != null && toStation != null) {

                // need to do this get the connected stations...!!!
                template.fetch(fromStation.getConnectedTo());
                template.fetch(toStation.getConnectedTo());

                fromStation.addStation(toStation);

                template.save(fromStation);

                System.out.println(from_tlc + " connected to: " + to_tlc);
            }
        }
    }

因此，当它尝试导入连接时，我收到以下错误：RELATIONSHIP[4434] has no property with propertyKey="__type__".

Exception in thread "main" org.neo4j.graphdb.NotFoundException: RELATIONSHIP[4434] has no property with propertyKey="__type__".
    at org.neo4j.kernel.impl.core.RelationshipProxy.getProperty(RelationshipProxy.java:195)
    at org.springframework.data.neo4j.support.typerepresentation.AbstractIndexBasedTypeRepresentationStrategy.readAliasFrom(AbstractIndexBasedTypeRepresentationStrategy.java:126)
    at org.springframework.data.neo4j.support.mapping.TRSTypeAliasAccessor.readAliasFrom(TRSTypeAliasAccessor.java:36)
    at 

所以我基本上对这个错误感到困惑，希望能得到一些帮助。

如果有更好的方法，请告诉我。

总经理

Answer 1

你能检查 id 为 4434 的关系吗？如果真的没有那个属性，又是什么关系。

这意味着 SDN 无法加载映射到 Java 类型的关系，因为不知何故类型信息未存储在其上。

您可以在事后通过template.postEntityCreation(rel, ConnectedTo.class); 做到这一点