Getting Neo4j cypher queries to work in java GraphRepository

**MichaelJaniak** · Aug 5th, 2012, 10:58 PM

I'm using a Neo4j database with various node classes and would like to search through the parameter strings of one particular node class. For example, if I have three nodes in class.MyNode, one with String name = "foo", another with name = "bar" and a third with name = "car", if I search for "ar", I would like to return a list containing nodes "bar" and "car".

The following cypher query works perfectly well in Neo4j's data browser :

Code:

START n=node:__types__(className='com.myapp.MyNode')
WHERE n.name=~ /(?i).*xyz.*/
RETURN n

However, when I add it to my repository, it returns all the nodes of class.MyNode and not the subset I need. Here is the code I've been using for the repository:

Code:

public interface MyNodeRepository extends GraphRepository<MyNode>,
	RelationshipOperationsRepository<MyNode>,
	NamedIndexRepository<MyNode>{
	
	@Query(	"START n=node:__types__(className='com.myapp.MyNode')"+ 
			"WHERE n.name=~ /(?i).*{0}.*/"+
			"RETURN n")
        Set<MyNode> getNodes(String search);	
}

And here is the node:

Code:

@NodeEntity
public class MyNode {
	@Indexed(indexType=IndexType.FULLTEXT, indexName="name") 
	@Fetch private String name;

        etc
}

I'm passing parameters just like the bible suggests and I've been pulling my hair out trying to figure out why this doesn't work.

Any thoughts on how to fix this would be much appreciated!!!

**lassewesth** · Aug 6th, 2012, 03:15 AM

Michael,

I'd suggest taking advantage of SDN's auto-repo-foo: http://static.springsource.org/sprin.../html/#d5e1308

Code:

@NodeEntity
class MyNode {
    @GraphId
    private Long id;

    @Indexed(indexType = IndexType.FULLTEXT, indexName = "name")
    private String name;

    MyNode() {
    }

    public MyNode(String name) {
        this.name = name;
    }
}

interface MyNodeRepository extends GraphRepository<MyNode> {
    Page<MyNode> findByNameLike(String name, Pageable page);
}

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration
public class FullTextSearchTests {
    @Autowired
    private MyNodeRepository myNodeRepository;

    @Configuration
    @EnableNeo4jRepositories
    static class Config extends Neo4jConfiguration {
        @Bean
        public GraphDatabaseService graphDatabaseService() {
            return new ImpermanentGraphDatabase();
        }
    }

    @Test
    public void shouldFindBySubstring() throws Exception {
        myNodeRepository.save(new MyNode("foo"));
        myNodeRepository.save(new MyNode("bar"));
        myNodeRepository.save(new MyNode("car"));

        assertThat(myNodeRepository.findByNameLike("*ar*", new PageRequest(0, 20)).getNumberOfElements(), is(2));
        assertThat(myNodeRepository.findByNameLike("*o", new PageRequest(0, 20)).getNumberOfElements(), is(1));
        assertThat(myNodeRepository.findByNameLike("ca?", new PageRequest(0, 20)).getNumberOfElements(), is(1));
    }
}

**MichaelJaniak** · Aug 6th, 2012, 01:47 PM

Thank you for the prompt reply! That is working for me now.

**MichaelJaniak** · Aug 7th, 2012, 01:33 PM

Sorry but I have to get back to this problem. Although the auto-repo is good for simple queries, I still need to use the regular expression for more complicated queries.

For example:

Code:

public interface MyRepository extends GraphRepository<User>,
	RelationshipOperationsRepository<User>,
	NamedIndexRepository<User>{
	
	@Query(	"START user=node({0}) "+
	"MATCH user-[:FRIENDS*1..2]-friends "+
	"WITH user, friends "+
	"MATCH friends-[:REL*1]->relatives "+
	"WHERE relatives.name=~ /(?i).*{1}.*/ "+
	"RETURN relatives")	
	Set<User> findRelativesOfFriends(long userId, String search);
}

This works in the data browser, it returns a subset of relatives, but in java regardless of what search parameter I pass, it always returns the whole set.

Am I doing something wrong?

**lassewesth** · Aug 8th, 2012, 05:58 AM

Originally Posted by MichaelJaniak

Code:

public interface MyRepository extends GraphRepository<User>,
	RelationshipOperationsRepository<User>,
	NamedIndexRepository<User>{
	
	@Query(	"START user=node({0}) "+
	"MATCH user-[:FRIENDS*1..2]-friends "+
	"WITH user, friends "+
	"MATCH friends-[:REL*1]->relatives "+
	"WHERE relatives.name=~ /(?i).*{1}.*/ "+
	"RETURN relatives")	
	Set<User> findRelativesOfFriends(long userId, String search);
}

This works in the data browser, it returns a subset of relatives, but in java regardless of what search parameter I pass, it always returns the whole set.

Well, it actually does what you ask it; so it interprets that regex as

Code:

match .* one time, then match .* a bunch of times

- the {1} is not substituted, it is taken literally

Instead, do

Code:

@Query(	"START user=node({0}) "+
	"MATCH user-[:FRIENDS*1..2]-friends "+
	"WITH user, friends "+
	"MATCH friends-[:REL*1]->relatives "+
	"WHERE relatives.name=~ {1} "+
	"RETURN relatives")	
	Set<User> findRelativesOfFriends(long userId, String regex);

...

myRepo.findRelativesOfFriends(42, "(?i).*my search string.*");

Let me know if it works.

Regards,

Lasse

**MichaelJaniak** · Aug 8th, 2012, 09:52 AM

That's perfect, works exactly like that, thank you for your help!

**MichaelJaniak** · Aug 21st, 2012, 10:44 PM

Sorry to flog a dead horse but getting cypher to work in the repository is often frustrating.

This code works exactly as expected:

Code:

Set<Note> query =  repo.search(id, "(?i).*"+search+".*");
....

@Query(
 "START user=node({0}) "
 "MATCH user-[:FRIEND*0..3]-friends, "+
 "friends-[:NOTE*1]->notes "+
 "WHERE notes.note=~ {1} "+
 "RETURN notes")
Set<Note> search(long id, String search);

But once I add more complexity, things start going tits up. This works in webadmin:

Code:

START user=node(548)
MATCH user-[:FRIEND*0..3]-friends
WITH distinct(friends) AS group, user
MATCH group-[:NOTE*1]->notes
WHERE notes.note=~ /(?i).*steve.*/
OR notes.tags=~ /(?i).*steve.*/
WITH notes, group, user
MATCH path=shortestPath(user-[:FRIEND*]-group)
RETURN notes, group, length(path)
ORDER BY length(path) ASC

If I hard code the regular expressions, this works in my repository:

Code:

Iterable<HashMap<String, Object>> query = repo.search2(id, "(?i).*"+search+".*");
....

    @Query(
    	"START user=node({0}) "+
    	"MATCH user-[:FRIEND*0..3]-friends "+
    	"WITH distinct(friends) AS group, user "+
    	"MATCH group-[:NOTE*1]->notes "+
    	"WHERE notes.note=~ /(?i).*steve.*/ "+
    	"OR notes.tags=~ /(?i).*steve.*/ "+
    	"WITH notes, group, user "+
    	"MATCH path=shortestPath(user-[:FRIEND*]-group) "+
    	"RETURN notes, group, length(path) "+
    	"ORDER BY length(path) ASC " )
    Iterable<HashMap<String, Object>> search2(long id, String search);

But the moment I pass in the search variable...

Code:

    @Query(
    	"START user=node({0}) "+
    	"MATCH user-[:FRIEND*0..3]-friends "+
    	"WITH distinct(friends) AS group, user "+
    	"MATCH group-[:NOTE*1]->notes "+
    	"WHERE notes.note=~ {1} "+
    	"OR notes.tags=~ {1} "+
    	"WITH notes, group, user "+
    	"MATCH path=shortestPath(user-[:FRIEND*]-group) "+
    	"RETURN notes, group, length(path) "+
    	"ORDER BY length(path) ASC " )
    Iterable<HashMap<String, Object>> search2(long id, String search);

The query fails and I get a BadInputException, which makes no sense since the query works in webadmin, it works in java with a fixed regex, and works in java with a parameter, albeit for a smaller query.

Again, any help would be much appreciated. Here is the stack trace if it's of any use

Code:

    Expected a parameter named 1 at
BadInputException
   org.neo4j.server.rest.repr.RepresentationExceptionHandlingIterable.exceptionOnHasNext(RepresentationExceptionHandlingIterable.java:51)
   org.neo4j.helpers.collection.ExceptionHandlingIterable$1.hasNext(ExceptionHandlingIterable.java:61)
   org.neo4j.helpers.collection.IteratorWrapper.hasNext(IteratorWrapper.java:42)
   org.neo4j.server.rest.repr.ListRepresentation.serialize(ListRepresentation.java:58)
   org.neo4j.server.rest.repr.Serializer.serialize(Serializer.java:75)
   org.neo4j.server.rest.repr.MappingSerializer.putList(MappingSerializer.java:61)
   org.neo4j.server.rest.repr.CypherResultRepresentation.serialize(CypherResultRepresentation.java:50)
   org.neo4j.server.rest.repr.MappingRepresentation.serialize(MappingRepresentation.java:42)
   org.neo4j.server.rest.repr.OutputFormat.format(OutputFormat.java:170)
   org.neo4j.server.rest.repr.OutputFormat.formatRepresentation(OutputFormat.java:120)
   org.neo4j.server.rest.repr.OutputFormat.response(OutputFormat.java:107)
   org.neo4j.server.rest.repr.OutputFormat.ok(OutputFormat.java:55)
   org.neo4j.server.rest.web.CypherService.cypher(CypherService.java:68)
   java.lang.reflect.Method.invoke(Method.java:601)
   org.neo4j.server.statistic.StatisticFilter.doFilter(StatisticFilter.java:62)
Caused by:

org.neo4j.rest.graphdb.RestResultException: Expected a parameter named 1 at
BadInputException

**MichaelHunger** · Aug 22nd, 2012, 07:58 AM

Sorry, you ran into a cypher problem, which will be fixed in this pull request: https://github.com/neo4j/community/pull/796

So it will be available in Neo4j snapshot or in the next milestone or RC.

Sorry for that.

Michael

**MichaelJaniak** · Aug 22nd, 2012, 05:17 PM

Ok, good to know. I can change my approach.

**pedro.abalo** · Jan 3rd, 2013, 06:43 AM

Originally Posted by MichaelJaniak

Ok, good to know. I can change my approach.

I need the same thing, how I can change my approach to the problem?, This remains unresolved: (

thank you very much

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