Getting error org.neo4j.rest.graphdb.entity.RestNode cannot be cast to java.lang.Iterable

Question

I am trying to filter feeds which contains user actvitity. I am using @QueryResult object to retrieve the result. I need both the feeds and the relationship information of user Liked Feeds. But while retrieving the feeds getting error: org.neo4j.rest.graphdb.entity.RestNode cannot be cast to java.lang.Iterable. (I am using SDN 3.3.0.RELEASE and neo4j 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);

If I convert the query as suggested by Luanne, I am getting following error: Type mismatch: expected Map, Node or Relationship but was Collection.

New Query:

    @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 );

Luanne · Accepted Answer · 2015-06-16 07:50:07Z

2

Your query returns feed as f, a node, and rel as r, a relationship. But the FeedsIterableResult expects them to be collections. Each "row" returned by that query will contain a feed node and a rel relationship.

To match your QueryResult, you would have to change your Cypher query to return collections of feeds and rels. Or change FeedsIterableResult to expect single nodes and relationships and have getAllFavoriteFeeds return a Collection of FeedsIterableResult.

answered Jun 16, 2015 at 7:50

Luanne

19.4k1 gold badge42 silver badges52 bronze badges

Sign up to request clarification or add additional context in comments.

6 Comments

Anshul Goel Over a year ago

But can i send collect(feed) and collect(rel) in union? I tried this too, but it was not working.

Anshul Goel Over a year ago

It should return two columns for feeds and relation respectively but right now giving exception.

Luanne Over a year ago

I am not sure if this is the cause of your new exception, but the union will return two rows, one row from each union. But you're mapping onto a single FeedsIterableResult.

Anshul Goel Over a year ago

Its ok Luanne I have got the result using your other suggestion, by returning single nodes. But there is one minor problem in that too. The skip and limit I have applied is just working for the second union but I want it to work on whole result.

Luanne Over a year ago

That's not possible currently. You can apply it to each part of the union but not the entire resultset.

|

Collectives™ on Stack Overflow

Getting error org.neo4j.rest.graphdb.entity.RestNode cannot be cast to java.lang.Iterable

1 Answer 1

6 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

6 Comments

Your Answer

Sign up or log in

Post as a guest

Related