From neo4j-skills
Configures Spring Boot apps with Neo4j using Spring Data Neo4j: @Node entities, @Relationship mappings, Neo4jRepository, @Query Cypher, application.yml, Neo4jClient, transactions, auditing, and Spring AI Neo4jVectorStore.
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- Configuring Spring Boot with Neo4j (`spring-boot-starter-data-neo4j`)
Provides Spring Data Neo4j integration patterns for Spring Boot apps, including @Node entities, @Relationship, Cypher @Query, imperative/reactive repositories, graph traversals, and embedded testing.
Guides Neo4j Java Driver v6 usage in Java/Kotlin: Maven/Gradle setup, driver lifecycle, sessions/transactions (executeRead/Write, executableQuery), async/reactive, errors, pooling, bookmarks.
Designs Spring Data JPA repositories, projections, query patterns, custom repos, CQRS read models, entity relationships, and persistence fixes for Java Spring Boot projects.
Share bugs, ideas, or general feedback.
spring-boot-starter-data-neo4j)@Node entity classes and @Relationship/@RelationshipProperties mappingsNeo4jRepository or ReactiveNeo4jRepository interfaces@Query annotations with Cypher on repository methodsapplication.yml for Neo4j connectionNeo4jClient or Neo4jTemplateNeo4jVectorStore for vector search in Spring appsneo4j-driver-java-skillneo4j-cypher-skillneo4j-migration-skillneo4j-gds-skill| SDN | Spring Boot | Spring Framework | Java | Neo4j |
|---|---|---|---|---|
| 8.0.x | 3.3.x / 3.4.x | 6.2.x | 17+ | 5.15+ |
| 8.1.x | 3.4.x+ | 7.0.x | 17+ | 5.15+ |
| 7.5.x | 3.2.x | 6.1.x | 17+ | 4.4+ |
Use spring-boot-starter-data-neo4j — it pulls SDN + driver. No explicit SDN version needed when using Spring Boot BOM.
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-neo4j</artifactId>
</dependency>
implementation 'org.springframework.boot:spring-boot-starter-data-neo4j'
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-webflux</artifactId>
</dependency>
spring:
neo4j:
uri: ${NEO4J_URI:bolt://localhost:7687}
authentication:
username: ${NEO4J_USERNAME:neo4j}
password: ${NEO4J_PASSWORD}
data:
neo4j:
database: ${NEO4J_DATABASE:neo4j}
spring:
neo4j:
uri: ${NEO4J_URI} # neo4j+s://xxxx.databases.neo4j.io
authentication:
username: ${NEO4J_USERNAME:neo4j}
password: ${NEO4J_PASSWORD}
data:
neo4j:
database: ${NEO4J_DATABASE:neo4j}
Credentials: store in .env; never hardcode. Verify .env is in .gitignore.
import org.springframework.data.neo4j.core.schema.*;
// Internal generated ID (default for most cases)
@Node("Person")
public class PersonEntity {
@Id @GeneratedValue private Long id; // element ID (Long)
private String name;
@Property("birth_year") private Integer birthYear; // custom property name
@Relationship(type = "KNOWS", direction = Relationship.Direction.OUTGOING)
private List<PersonEntity> friends = new ArrayList<>();
}
// UUID business key
@Node("Product")
public class ProductEntity {
@Id @GeneratedValue(generatorClass = GeneratedValue.UUIDStringGenerator.class)
private String id;
@Version private Long version; // optimistic locking; required with business key
}
// User-assigned key (caller sets value; no @GeneratedValue)
@Node("Country")
public class CountryEntity {
@Id private String isoCode;
private String name;
}
// Multiple static labels
@Node(primaryLabel = "Vehicle", labels = {"Car", "Auditable"})
public class CarEntity { ... }
// Runtime labels
@Node("Content")
public class ContentEntity {
@Id @GeneratedValue private Long id;
@DynamicLabels private Set<String> tags = new HashSet<>(); // labels added at runtime
}
Use @RelationshipProperties when the relationship itself carries data.
@RelationshipProperties
public class RolesRelationship {
@RelationshipId // internal relationship ID; required
private Long id;
private List<String> roles;
@TargetNode // marks the other end of the relationship
private PersonEntity person;
}
@Node("Movie")
public class MovieEntity {
@Id @GeneratedValue
private Long id;
private String title;
@Relationship(type = "ACTED_IN", direction = Relationship.Direction.INCOMING)
private List<RolesRelationship> actorsAndRoles = new ArrayList<>();
}
import org.springframework.data.neo4j.repository.Neo4jRepository;
public interface PersonRepository extends Neo4jRepository<PersonEntity, Long> {
Optional<PersonEntity> findByName(String name);
List<PersonEntity> findByBirthYearBetween(int from, int to);
List<PersonEntity> findByNameContainingIgnoreCase(String fragment);
long countByBirthYearGreaterThan(int year);
void deleteByName(String name);
}
// CORRECT: $param bound parameter
@Query("MATCH (p:Person {name: $name})-[:KNOWS]->(f:Person) RETURN f")
List<PersonEntity> findFriendsOf(String name);
// With pagination
@Query(value = "MATCH (p:Person) RETURN p ORDER BY p.name",
countQuery = "MATCH (p:Person) RETURN count(p)")
Page<PersonEntity> findAllPaged(Pageable pageable);
// Return relationship-rich entity; map target via @Node return
@Query("MATCH (m:Movie)<-[r:ACTED_IN]-(p:Person {name: $name}) RETURN m, collect(r), collect(p)")
List<MovieEntity> findMoviesActedInBy(String name);
Security rule: NEVER string-concatenate user input into Cypher. Always use $paramName.
Page<PersonEntity> findByBirthYearGreaterThan(int year, Pageable pageable);
List<PersonEntity> findTop10ByOrderByNameAsc();
List<PersonEntity> findByName(String name, Sort sort);
Usage:
Pageable page = PageRequest.of(0, 20, Sort.by("name").ascending());
Page<PersonEntity> result = repo.findByBirthYearGreaterThan(1980, page);
public interface PersonSummary {
String getName();
Integer getBirthYear();
}
List<PersonSummary> findByBirthYearLessThan(int year);
public record PersonDto(String name, Integer birthYear) {}
List<PersonDto> findByName(String name);
<T> List<T> findByName(String name, Class<T> type);
// Usage
repo.findByName("Alice", PersonSummary.class);
repo.findByName("Alice", PersonEntity.class);
public interface FullName {
@Value("#{target.name + ' (' + target.birthYear + ')'}") String getDisplayName();
}
import org.springframework.data.neo4j.repository.ReactiveNeo4jRepository;
import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;
public interface ReactivePersonRepository extends ReactiveNeo4jRepository<PersonEntity, Long> {
Mono<PersonEntity> findByName(String name);
@Query("MATCH (p:Person {name: $name})-[:KNOWS]->(f) RETURN f")
Flux<PersonEntity> findFriendsOf(String name);
}
Do NOT mix imperative and reactive database access in the same application context.
Fragment pattern — use when @Query is not enough.
// 1. Fragment interface
public interface PersonRepositoryCustom {
List<PersonEntity> findByComplexCriteria(String criteria);
}
// 2. Impl — must end with "Impl"
public class PersonRepositoryCustomImpl implements PersonRepositoryCustom {
private final Neo4jClient neo4jClient;
PersonRepositoryCustomImpl(Neo4jClient c) { this.neo4jClient = c; }
@Override
public List<PersonEntity> findByComplexCriteria(String c) {
return new ArrayList<>(neo4jClient
.query("MATCH (p:Person) WHERE p.name CONTAINS $c RETURN p").bind(c).to("c")
.fetchAs(PersonEntity.class)
.mappedBy((t, r) -> { var e = new PersonEntity(); e.setName(r.get("p").asNode().get("name").asString()); return e; })
.all());
}
}
// 3. Compose
public interface PersonRepository extends Neo4jRepository<PersonEntity, Long>, PersonRepositoryCustom {}
Use when @Query is insufficient or you need full control over Cypher execution.
// Bind params + fetch single scalar
neo4jClient.query("MATCH (p:Person {name: $name}) RETURN count(*) AS cnt")
.bind("Alice").to("name")
.fetchAs(Long.class)
.mappedBy((t, r) -> r.get("cnt").asLong())
.one();
// Bind + run write (no result)
neo4jClient.query("MERGE (p:Person {name: $name})")
.bind(personName).to("name")
.run();
// Custom object mapping
neo4jClient.query("MATCH (p:Person)-[:DIRECTED]->(m:Movie) WHERE p.name=$n RETURN p, collect(m) AS movies")
.bind("Lilly Wachowski").to("n")
.fetchAs(Director.class)
.mappedBy((typeSystem, record) -> new Director(
record.get("p").asNode().get("name").asString(),
record.get("movies").asList(v -> new Movie(v.get("title").asString()))
)).one();
Full API: references/neo4j-client.md
@Service
@Transactional // class-level: all methods transactional
public class PersonService {
@Transactional(readOnly = true) // read-only hint
public Optional<PersonEntity> findByName(String name) { ... }
@Transactional // explicit write
public PersonEntity save(PersonEntity p) { return repository.save(p); }
}
Neo4jTransactionManager auto-configured. Do NOT mix with JPA PlatformTransactionManager without explicit qualifier. Use @Transactional on concrete class, not interface.
<dependency>
<groupId>org.springframework.ai</groupId>
<artifactId>spring-ai-starter-vector-store-neo4j</artifactId>
</dependency>
spring:
ai:
vectorstore:
neo4j:
initialize-schema: true # creates vector index on first run
index-name: my-index
embedding-dimension: 1536 # must match your embedding model
distance-type: cosine # cosine (default) or euclidean
label: Document # node label for stored chunks
embedding-property: embedding # property for the vector
Requires Neo4j 5.15+. Reuses spring.neo4j.* connection config.
@Autowired VectorStore vectorStore;
// Store
vectorStore.add(List.of(new Document("text", Map.of("author", "alice"))));
// Similarity search
List<Document> results = vectorStore.similaritySearch(
SearchRequest.builder().query("spring neo4j").topK(5).similarityThreshold(0.75).build()
);
// With metadata filter
vectorStore.similaritySearch(
SearchRequest.builder().query("spring neo4j").topK(5)
.filterExpression("author == 'alice'").build()
);
| Error | Cause | Fix |
|---|---|---|
MappingException: Could not find entity | Entity not scanned | Check @EnableNeo4jRepositories base package |
| Relationships null after load | Default depth may skip deep rels | Use @Query with RETURN m, collect(r), collect(p) |
| N+1 queries | Per-entity relationship fetch | Rewrite with single @Query; use projections |
OptimisticLockingFailureException | Stale @Version on concurrent write | Retry in service layer |
IllegalStateException: Cannot mix reactive/imperative | Both repo types in same context | Pick one stack |
| Projection null fields | Getter name mismatch | Match getter to property name; check @Property alias |
@Query empty with rels | Missing collect(r), collect(p) | Return root node + rels + related nodes together |
Cannot delete node, node has relationships | deleteById without detach | Use @Query with DETACH DELETE |
| Transaction not rolling back | @Transactional on interface | Apply on concrete service class |
SDN loads related entities eagerly up to a configured depth (default: 1 hop). For deeper graphs:
// Explicit @Query to control what gets loaded
@Query("""
MATCH (m:Movie)<-[r:ACTED_IN]-(p:Person)
WHERE m.title = $title
RETURN m, collect(r), collect(p)
""")
Optional<MovieEntity> findByTitleWithCast(String title);
collect(r), collect(p) in RETURN is required for SDN to map @RelationshipProperties correctly.
@Node uses explicit label string, not default class name@Id @GeneratedValue (or @Id + @Version for business key with optimistic lock)@RelationshipProperties class has @RelationshipId and @TargetNode@Relationship direction is explicit (OUTGOING / INCOMING)@Query Cypher uses $paramName — no string concatenation@Query returns collect(r), collect(p) alongside root nodeapplication.yml (avoids default DB ambiguity)@Transactional on concrete service class (not interface).env in .gitignorespring.ai.vectorstore.neo4j.initialize-schema: true for first run (Spring AI)