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meistermeiermeistermeier
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GH-2583 - Improve relationship mapping.
Accept maximum of two iterations for a relationship before it gets removed from the candidate list.
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‎src/main/java/org/springframework/data/neo4j/core/mapping/DefaultNeo4jEntityConverter.java

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@@ -615,6 +615,13 @@ private Optional<Object> createInstanceOfRelationships(Neo4jPersistentProperty p
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for (Relationship possibleRelationship : allMatchingTypeRelationshipsInResult) {
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if (targetIdSelector.apply(possibleRelationship) == targetNodeId) {
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// Reduce the amount of relationships in the candidate list.
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// If this relationship got processed twice (OUTGOING, INCOMING), it is never needed again
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// and therefor should not be in the list.
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// Otherwise, for highly linked data it could potentially cause a StackOverflowError.
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if (knownObjects.hasProcessedRelationshipCompletely(possibleRelationship.id())) {
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relationshipsFromResult.remove(possibleRelationship);
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}
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// If the target is the same(equal) node, get the related object from the cache.
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// Avoiding the call to the map method also breaks an endless cycle of trying to finish
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// the property population of _this_ object.
@@ -777,6 +784,8 @@ static class KnownObjects {
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private final Set<Long> previousRecords = new HashSet<>();
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private final Set<Long> idsInCreation = new HashSet<>();
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private final Map<Long, Integer> processedRelationships = new HashMap<>();
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private void storeObject(@Nullable Long internalId, Object object) {
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if (internalId == null) {
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return;
@@ -863,6 +872,25 @@ private boolean alreadyMappedInPreviousRecord(@Nullable Long internalId) {
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}
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}
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private boolean hasProcessedRelationshipCompletely(Long relationshipId) {
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try {
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write.lock();
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read.lock();
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int amount = processedRelationships.computeIfAbsent(relationshipId, s -> 0);
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if (amount == 2) {
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return true;
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}
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processedRelationships.put(relationshipId, amount + 1);
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return false;
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} finally {
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write.unlock();
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read.unlock();
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}
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}
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/**
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* Mark all currently existing objects as mapped.
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*/

‎src/test/java/org/springframework/data/neo4j/integration/issues/gh2583/GH2583IT.java

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package org.springframework.data.neo4j.integration.issues.gh2583;
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import org.junit.jupiter.api.BeforeEach;
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import org.junit.jupiter.api.Test;
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import org.neo4j.driver.Driver;
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import org.neo4j.driver.Session;
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import org.springframework.beans.factory.annotation.Autowired;
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import org.springframework.context.annotation.Bean;
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import org.springframework.context.annotation.Configuration;
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import org.springframework.data.domain.Page;
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import org.springframework.data.domain.PageRequest;
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import org.springframework.data.neo4j.core.DatabaseSelectionProvider;
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import org.springframework.data.neo4j.core.transaction.Neo4jBookmarkManager;
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import org.springframework.data.neo4j.core.transaction.Neo4jTransactionManager;
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import org.springframework.data.neo4j.repository.config.EnableNeo4jRepositories;
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import org.springframework.data.neo4j.test.BookmarkCapture;
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import org.springframework.data.neo4j.test.Neo4jExtension;
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import org.springframework.data.neo4j.test.Neo4jImperativeTestConfiguration;
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import org.springframework.data.neo4j.test.Neo4jIntegrationTest;
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import org.springframework.transaction.PlatformTransactionManager;
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import org.springframework.transaction.annotation.EnableTransactionManagement;
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import java.util.Collection;
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import java.util.Collections;
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import java.util.List;
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import static org.assertj.core.api.Assertions.assertThat;
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@Neo4jIntegrationTest
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public class GH2583IT {
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protected static Neo4jExtension.Neo4jConnectionSupport neo4jConnectionSupport;
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@BeforeEach
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void setupData(@Autowired Driver driver, @Autowired BookmarkCapture bookmarkCapture) {
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try (Session session = driver.session(bookmarkCapture.createSessionConfig())) {
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session.run("MATCH (n) DETACH DELETE n").consume();
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session.run("CREATE (n:GH2583Node)-[:LINKED]->(m:GH2583Node)-[:LINKED]->(n)-[:LINKED]->(m)" +
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"-[:LINKED]->(n)-[:LINKED]->(m)-[:LINKED]->(n)-[:LINKED]->(m)" +
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"-[:LINKED]->(n)-[:LINKED]->(m)-[:LINKED]->(n)-[:LINKED]->(m)" +
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"-[:LINKED]->(n)-[:LINKED]->(m)-[:LINKED]->(n)-[:LINKED]->(m)" +
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"-[:LINKED]->(n)-[:LINKED]->(m)-[:LINKED]->(n)-[:LINKED]->(m)" +
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"-[:LINKED]->(n)-[:LINKED]->(m)-[:LINKED]->(n)-[:LINKED]->(m)" +
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"-[:LINKED]->(n)-[:LINKED]->(m)-[:LINKED]->(n)-[:LINKED]->(m)" +
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"-[:LINKED]->(n)-[:LINKED]->(m)-[:LINKED]->(n)-[:LINKED]->(m)" +
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"-[:LINKED]->(n)-[:LINKED]->(m)-[:LINKED]->(n)-[:LINKED]->(m)" +
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"-[:LINKED]->(n)-[:LINKED]->(m)-[:LINKED]->(n)-[:LINKED]->(m)" +
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"-[:LINKED]->(n)-[:LINKED]->(m)-[:LINKED]->(n)-[:LINKED]->(m)").consume();
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bookmarkCapture.seedWith(session.lastBookmark());
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}
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}
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@Test
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void mapStandardCustomQueryWithLotsOfRelationshipsProperly(@Autowired GH2583Repository repository) {
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Page<GH2583Node> nodePage = repository.getNodesByCustomQuery(PageRequest.of(0, 300));
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List<GH2583Node> nodes = nodePage.getContent();
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assertThat(nodes).hasSize(2);
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}
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@Configuration
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@EnableTransactionManagement
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@EnableNeo4jRepositories(considerNestedRepositories = true)
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static class Config extends Neo4jImperativeTestConfiguration {
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@Bean
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public BookmarkCapture bookmarkCapture() {
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return new BookmarkCapture();
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}
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@Override
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public PlatformTransactionManager transactionManager(
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Driver driver, DatabaseSelectionProvider databaseNameProvider) {
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BookmarkCapture bookmarkCapture = bookmarkCapture();
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return new Neo4jTransactionManager(driver, databaseNameProvider,
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Neo4jBookmarkManager.create(bookmarkCapture));
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}
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@Override
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protected Collection<String> getMappingBasePackages() {
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return Collections.singleton(GH2583Node.class.getPackage().getName());
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}
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@Bean
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public Driver driver() {
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return neo4jConnectionSupport.getDriver();
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}
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@Override
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public boolean isCypher5Compatible() {
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return neo4jConnectionSupport.isCypher5SyntaxCompatible();
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}
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}
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}

‎src/test/java/org/springframework/data/neo4j/integration/issues/gh2583/GH2583Node.java

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package org.springframework.data.neo4j.integration.issues.gh2583;
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import org.springframework.data.neo4j.core.schema.GeneratedValue;
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import org.springframework.data.neo4j.core.schema.Id;
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import org.springframework.data.neo4j.core.schema.Node;
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import org.springframework.data.neo4j.core.schema.Relationship;
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import java.util.List;
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/**
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* A simple node with bidirectional relationship mapping to the very same type.
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*/
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@Node
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public class GH2583Node {
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@Id
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@GeneratedValue
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Long id;
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@Relationship(type = "LINKED", direction = Relationship.Direction.OUTGOING)
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public List<GH2583Node> outgoingNodes;
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@Relationship(type = "LINKED", direction = Relationship.Direction.INCOMING)
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public List<GH2583Node> incomingNodes;
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}

‎src/test/java/org/springframework/data/neo4j/integration/issues/gh2583/GH2583Repository.java

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package org.springframework.data.neo4j.integration.issues.gh2583;
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import org.springframework.data.domain.Page;
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import org.springframework.data.domain.Pageable;
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import org.springframework.data.neo4j.repository.Neo4jRepository;
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import org.springframework.data.neo4j.repository.query.Query;
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public interface GH2583Repository extends Neo4jRepository<GH2583Node, Long> {
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@Query(value = "MATCH (s:GH2583Node) " +
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"WITH s OPTIONAL MATCH (s)-[r:LINKED]->(t:GH2583Node) " +
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"RETURN s, collect(r), collect(t) " +
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":#{orderBy(#pageable)} SKIP $skip LIMIT $limit",
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countQuery = "MATCH (s:hktxjm) RETURN count(s)")
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Page<GH2583Node> getNodesByCustomQuery(Pageable pageable);
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}

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