使用 Neo4j 和 JavaScript 构建应用程序

npm i neo4j-driver

var neo4j = require('neo4j-driver');
(async () => {
  // URI examples: 'neo4j://localhost', 'neo4j+s://xxx.databases.neo4j.io'
  const URI = '<URI to Neo4j database>'
  const USER = '<Username>'
  const PASSWORD = '<Password>'
  let driver

  try {
    driver = neo4j.driver(URI, neo4j.auth.basic(USER, PASSWORD))
    const serverInfo = await driver.getServerInfo()
    console.log('Connection established')
    console.log(serverInfo)
  } catch(err) {
    console.log(`Connection error\n${err}\nCause: ${err.cause}`)
  }
})();

const neo4j = require('neo4j-driver');

(async () => {
  const URI = '<URI for Neo4j database>'
  const USER = '<Username>'
  const PASSWORD = '<Password>'
  let driver, session
  let employeeThreshold = 10

  try {
    driver = neo4j.driver(URI, neo4j.auth.basic(USER, PASSWORD))
    await driver.verifyConnectivity()
  } catch(err) {
    console.log(`-- Connection error --\n${err}\n-- Cause --\n${err.cause}`)
    await driver.close()
    return
  }

  session = driver.session({ database: 'neo4j' })
  for(let i=0; i<100; i++) {
    const name = `Neo-${i.toString()}`
    const orgId = await session.executeWrite(async tx => {
      let result, orgInfo

      // Create new Person node with given name, if not already existing
      await tx.run(`
        MERGE (p:Person {name: $name})
        RETURN p.name AS name
        `, { name: name }
      )

      // Obtain most recent organization ID and number of people linked to it
      result = await tx.run(`
        MATCH (o:Organization)
        RETURN o.id AS id, COUNT{(p:Person)-[r:WORKS_FOR]->(o)} AS employeesN
        ORDER BY o.createdDate DESC
        LIMIT 1
      `)
      if(result.records.length > 0) {
        orgInfo = result.records[0]
      }

      if(orgInfo != undefined && orgInfo['employeesN'] == 0) {
        throw new Error('Most recent organization is empty.')
        // Transaction will roll back -> not even Person is created!
      }

      // If org does not have too many employees, add this Person to that
      if(orgInfo != undefined && orgInfo['employeesN'] < employeeThreshold) {
        result = await tx.run(`
          MATCH (o:Organization {id: $orgId})
          MATCH (p:Person {name: $name})
          MERGE (p)-[r:WORKS_FOR]->(o)
          RETURN $orgId AS id
          `, { orgId: orgInfo['id'], name: name }
        )

      // Otherwise, create a new Organization and link Person to it
      } else {
        result = await tx.run(`
          MATCH (p:Person {name: $name})
          CREATE (o:Organization {id: randomuuid(), createdDate: datetime()})
          MERGE (p)-[r:WORKS_FOR]->(o)
          RETURN o.id AS id
          `, { name: name }
        )
      }

      // Return the Organization ID to which the new Person ends up in
      return result.records[0].get('id')
    })
    console.log(`User ${name} added to organization ${orgId}`)
  }
  await session.close()
  await driver.close()
})()

const driver = neo4j.driver(URI, neo4j.auth.basic(USER, PASSWORD))
let session = driver.session({ database: 'neo4j' })

// session/driver usage

session.close()
driver.close()