Missing converter from `java.util.Map` to `org.neo4j.driver.Value`.

[Bhavinpanchal20]

The below query works fine in SDN 5, But in SDN 6 they throw error.

UNWIND {0} AS row
MATCH (student:Student{guid:row.stuGuid}), (college:College{guid:row.collegeGuid})
CREATE (student)<-[:STUDENT_OF]-(college)
RETURN student.guid
public List addOwnerOfActvities(List<Map<String,String>> data);

Can anyone tell me How I resolve that issue?

[michael-simons]

Please tell us the error thrown.

[Bhavinpanchal20]

Sorry, My mistake. My problem is, that the above query does not throw any error but also they don't create a relationship and also do not return any value.

[michael-simons]

SDN does a lot of logging. If you set org.springframework.data.neo4j.cypher to trace, we can see the query and the parameters to it being logged.

The query here is correct, and depending on the parameters, it should create a relation.
However, SDN 6 is conceptionally different from SDN5 and it won't map arbitrary things back to you.

[Bhavinpanchal20]

i got this type error.
Caused by: org.springframework.core.convert.ConverterNotFoundException: No converter found capable of converting from type [java.util.HashMap] to type [org.neo4j.driver.Value]
at org.springframework.core.convert.support.GenericConversionService.handleConverterNotFound(GenericConversionService.java:322)
at org.springframework.core.convert.support.GenericConversionService.convert(GenericConversionService.java:195)
at org.springframework.core.convert.support.GenericConversionService.convert(GenericConversionService.java:175)
at org.springframework.data.neo4j.core.mapping.DefaultNeo4jConversionService.lambda$writeValue$3(DefaultNeo4jConversionService.java:117)
at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:195)
at java.base/java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1655)
at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484)
at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474)
at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:550)
at java.base/java.util.stream.AbstractPipeline.evaluateToArrayNode(AbstractPipeline.java:260)
at java.base/java.util.stream.ReferencePipeline.toArray(ReferencePipeline.java:517)
at java.base/java.util.stream.ReferencePipeline.toArray(ReferencePipeline.java:523)
at org.springframework.data.neo4j.core.mapping.DefaultNeo4jConversionService.writeValueImpl(DefaultNeo4jConversionService.java:143)
at org.springframework.data.neo4j.core.mapping.DefaultNeo4jConversionService.writeValue(DefaultNeo4jConversionService.java:126)
at org.springframework.data.neo4j.repository.query.Neo4jQuerySupport.convertParameter(Neo4jQuerySupport.java:204)
at org.springframework.data.neo4j.repository.query.Neo4jQuerySupport.convertParameter(Neo4jQuerySupport.java:154)
at org.springframework.data.neo4j.repository.query.StringBasedNeo4jQuery.lambda$bindParameters$8(StringBasedNeo4jQuery.java:221)
at java.base/java.lang.Iterable.forEach(Iterable.java:75)
at org.springframework.data.neo4j.repository.query.StringBasedNeo4jQuery.bindParameters(StringBasedNeo4jQuery.java:216)
at org.springframework.data.neo4j.repository.query.StringBasedNeo4jQuery.prepareQuery(StringBasedNeo4jQuery.java:183)
at org.springframework.data.neo4j.repository.query.AbstractNeo4jQuery.execute(AbstractNeo4jQuery.java:90)
at org.springframework.data.repository.core.support.RepositoryMethodInvoker.doInvoke(RepositoryMethodInvoker.java:137)
at org.springframework.data.repository.core.support.RepositoryMethodInvoker.invoke(RepositoryMethodInvoker.java:121)
at org.springframework.data.repository.core.support.QueryExecutorMethodInterceptor.doInvoke(QueryExecutorMethodInterceptor.java:159)
at org.springframework.data.repository.core.support.QueryExecutorMethodInterceptor.invoke(QueryExecutorMethodInterceptor.java:138)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
at org.springframework.data.projection.DefaultMethodInvokingMethodInterceptor.invoke(DefaultMethodInvokingMethodInterceptor.java:80)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:123)
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:388)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:119)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:137)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:97)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:215)
at com.sun.proxy.$Proxy166.addOwnerOfActvities(Unknown Source)

[michael-simons]

So you do get an error? I am confused.

[Bhavinpanchal20]

I apologize for this, but I got this type of error.

[Bhavinpanchal20]

Just tagging @michael-simons and @meistermeier as you would be more familiar.
Please suggest to me if the above query is having any defect. Thanks Team.

[michael-simons]

Your query is fine. But without your model, the repo and your call site I cannot reproduce it. Actual parameter values would help too. Thanks.

[Bhavinpanchal20]

Okay, Let me try to explain a bit.
First, I take

List<Map<String,String>> list = new ArrayList<>();
Map<String,String> map = new HashMap<>():
map.put("stuGuid",23232)
map.put("collegeGuid",87833)
list.add(map)

Now, This list passes to the below query.

The Query is :

@Query("""
	UNWIND {0} AS row
	MATCH (student:Student{guid:row.stuGuid}), (college:College{guid:row.collegeGuid})
	CREATE (student)<-[:STUDENT_OF]-(college) RETURN student.guid"""
)
List<String> addStudentToCollege(List<Map<String, String>> list);

Model:

@Node
class Student{
   private String guid;
   @Relationship(type = "STUDENT_OF", direction = Direction.OUTGOING)
    private College college;
}

@Node
class College{
 private String guid;
}

Here in this scenario, I get an Error that I already mention above.
Regards,
Bhavin Panchal

[michael-simons]

Thanks, @Bhavinpanchal20

This will be fixed and is an enhancement.

In the meantime you can use the following workaround.

import java.util.List;

import org.neo4j.driver.Value;
import org.springframework.data.neo4j.repository.Neo4jRepository;
import org.springframework.data.neo4j.repository.query.Query;

public interface CollegeRepository extends Neo4jRepository<College, String> {

	@Query("""
		UNWIND $0 AS row
		MATCH (student:Student{guid:row.stuGuid})
		MATCH (college:College{guid:row.collegeGuid})
		CREATE (student)<-[:STUDENT_OF]-(college) RETURN student.guid"""
	)
	List<String> addStudentToCollegeWorkaround(List<Value> list);
}

Note that I rewrote the query to use modern parameters ($whathever, the {} syntax is no longer supported in recent Neo4j databases).

The parameter is now of type List<org.neo4j.driver.Value>, call it like this

@Test
void listOfMapsShouldBeUsableAsArgumentsWithWorkaround(@Autowired Neo4jTemplate template,  @Autowired CollegeRepository collegeRepository) {

	var student = template.save(new Student("S1"));
	var college = template.save(new College("C1"));

	var pair = Map.of("stuGuid", student.getGuid(), "collegeGuid", college.getGuid());
	var listOfPairs = List.of(Values.value(pair));

	var uuids = collegeRepository.addStudentToCollegeWorkaround(listOfPairs);
	assertThat(uuids).containsExactly(student.getGuid());
}

Thanks again for reporting. One final advise, if you allow: Please use 3 consecutive tickmarks ` before and after a code snippet to format it proper. This really helps us a lot. I edited one of your answers to demonstrate.