獲取錯誤org.neo4j.rest.graphdb.entity.RestNode無法轉換爲java.lang.Iterable

Question

我試圖過濾包含用戶實體的提要。我正在使用@QueryResult對象來檢索結果。我需要訂閱源和用戶喜歡的訂閱源的關係信息。但是，當檢索提供的錯誤時：org.neo4j.rest.graphdb.entity.RestNode不能轉換爲java.lang.Iterable。 （我使用SDN 3.3.0.RELEASE和Neo4j的2.1.7）

@QueryResult 
public interface FeedsIterableResult { 
     @ResultColumn("f") 
     Collection<Feed> getFeeds(); 

     @ResultColumn("r") 
     Collection<UserInspiredByFeed> getPaths(); 
    } 

@Query("match (feed:Feed)-[:FEED_CONTAINS_TAG]->(t:Tag)<-[:USER_FAVORITED_TAG]-(u:User{username:{1}}) " 
      + "where feed.feedType in {0} " 
      + "with u, feed " 
      + "optional match (u)-[rel:USER_LIKED_FEED]->(feed) " 
      + "return feed as f, rel as r " 
      + "union match (u:User{username:{1}})-[:USER_FAVORITED_USER]->(u2:User)-[:USER_LIKED_FEED|:USER_CREATED_FEED]->(feed:Feed) " 
      + "where feed.feedType in {0} " 
      + "with u2, feed " 
      + "optional match (u2)-[rel:USER_LIKED_FEED]->(feed) " 
      + "return feed as f, rel as r "   
      + "order by f.timeAdded desc " 
      + "skip {2} limit {3}") 
FeedsIterableResult getAllFavoriteFeeds(String[] typeFilter, String userName, int skip, int limit); 

如果我轉換查詢通過盧安妮的建議，我收到以下錯誤： 類型不匹配：預計地圖，節點或關係，但是集合。

新查詢：

@QueryResult 
    public interface FeedsIterableResult { 
     @ResultColumn("f") 
     List<Feed> getFeeds(); 

     @ResultColumn("r") 
     List<UserInspiredByFeed> getPaths(); 
    } 

@Query("match (feed:Feed)-[:FEED_CONTAINS_TAG]->(t:Tag)<-[:USER_FAVORITED_TAG]-(u:User{username:{1}}) " 
      + "where feed.feedType in {0} " 
      + "with u, feed " 
      + "optional match (u)-[rel:USER_INSPIREDBY_FEED]->(feed) " 
      + "return collect(feed) as f, collect(rel) as r " 
      + "union match (u:User{username:{1}})-[:USER_FAVORITED_USER]->(u2:User)-[:USER_INSPIREDBY_FEED|:USER_CREATED_FEED]->(feed:Feed) " 
      + "where feed.feedType in {0} " 
      + "with u2, feed " 
      + "optional match (u2)-[rel:USER_INSPIREDBY_FEED]->(feed) " 
      + "return collect(feed) as f, collect(rel) as r "   
      + "order by f.timeAdded desc " 
      + "skip {2} limit {3}") 
FeedsIterableResult getAllFavoriteFeeds(String[] typeFilter, String userName, int skip, int limit); 

Answer 1

你的查詢返回feed as f，節點和rel as r有關係。 但FeedsIterableResult期望它們是集合。該查詢返回的每個「行」將包含一個feed節點和一個rel關係。

要匹配您的QueryResult，您將不得不更改您的Cypher查詢以返回Feed和rels的集合。或者更改FeedsIterableResult以期望單個節點和關係，並且getAllFavoriteFeeds返回FeedsIterableResult的集合。