用户定义的过程

package example;

import org.junit.jupiter.api.AfterAll;
import org.junit.jupiter.api.AfterEach;
import org.junit.jupiter.api.BeforeAll;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.TestInstance;
import org.neo4j.driver.Driver;
import org.neo4j.driver.GraphDatabase;
import org.neo4j.driver.Record;
import org.neo4j.driver.Result;
import org.neo4j.driver.Session;
import org.neo4j.driver.Value;
import org.neo4j.harness.Neo4j;
import org.neo4j.harness.Neo4jBuilders;

import static org.assertj.core.api.Assertions.assertThat;

@TestInstance(TestInstance.Lifecycle.PER_CLASS)
public class GetRelationshipTypesTests {

    private Driver driver;
    private Neo4j embeddedDatabaseServer;

    @BeforeAll
    void initializeNeo4j() {
        this.embeddedDatabaseServer = Neo4jBuilders.newInProcessBuilder()
                .withDisabledServer()
                .withProcedure(GetRelationshipTypes.class)
                .build();

        this.driver = GraphDatabase.driver(embeddedDatabaseServer.boltURI());
    }

    @AfterAll
    void closeDriver(){
        this.driver.close();
        this.embeddedDatabaseServer.close();
    }

    @AfterEach
    void cleanDb(){
        try(Session session = driver.session()) {
            session.run("MATCH (n) DETACH DELETE n");
        }
    }

    /**
     * We should be getting the correct values when there is only one type in each direction
     */
    @Test
    public void shouldReturnTheTypesWhenThereIsOneEachWay() {
        final String expectedIncoming = "INCOMING";
        final String expectedOutgoing = "OUTGOING";

        // In a try-block, to make sure we close the session after the test
        try(Session session = driver.session()) {

            //Create our data in the database.
            session.run(String.format("CREATE (:Person)-[:%s]->(:Movie {id:1})-[:%s]->(:Person)", expectedIncoming, expectedOutgoing));

            //Execute our procedure against it.
            Record record = session.run("MATCH (u:Movie {id:1}) CALL example.getRelationshipTypes(u) YIELD outgoing, incoming RETURN outgoing, incoming").single();

            //Get the incoming / outgoing relationships from the result
            assertThat(record.get("incoming").asList(Value::asString)).containsOnly(expectedIncoming);
            assertThat(record.get("outgoing").asList(Value::asString)).containsOnly(expectedOutgoing);
        }
    }
}

package org.example;

import org.neo4j.procedure.Context;
import org.neo4j.procedure.Name;
import org.neo4j.procedure.Procedure;
import org.neo4j.procedure.memory.ProcedureMemory;

import java.util.Arrays;
import java.util.stream.Stream;

public class MyProcedures {

    @Context
    public ProcedureMemory memory;

    record Output(Long value) {}

    @Procedure("org.example.memoryHungryRange")
    public Stream<Output> memoryHungryRange(@Name("size") int size) {
        final var tracker = memory.newTracker();

        // Register the allocation of the long array below
        tracker.allocateHeap(memory.heapEstimator().sizeOfLongArray(size));
        // The actual allocation
        final var result = new long[size];

        for (int i = 0; i < size; i++) result[i] = i;

        return Arrays.stream(result)
                .mapToObj(Output::new)
                // Release all registered allocations when the stream is closed
                .onClose(tracker::close);
    }
}