将 Neo4j Javascript 驱动程序导入 Angular 2 CLI 时出错

Question

你好， 在我的 Angular 2 CLI 应用程序中尝试使用 Neo4j 驱动程序时，我遇到了一些 module not found 错误。

我可能在尝试导入它时遗漏了一些东西。

• 我安装了它：ng install neo4j-driver
• 在我的服务中.ts：import 'neo4j-driver/lib/browser/neo4j-web';

• 尝试在服务中调用此示例代码：

  getFromDB(): void {
     var neo4j = require('neo4j-driver').v1;
     var driver = neo4j.driver("bolt://localhost", neo4j.auth.basic("neo4j", "pisikopat"));
  
     // Create a session to run Cypher statements in.
     // Note: Always make sure to close sessions when you are done using them!
     var session = driver.session();
  
     // Run a Cypher statement, reading the result in a streaming manner as records arrive:
     session
       .run("OPTIONAL MATCH (source)-[r]-(target) WHERE r is not null RETURN (source)")
       .subscribe({
         onNext: function (record) {
           console.log(record._fields);
         },
         onCompleted: function () {
           // Completed!
           session.close();
         },
         onError: function (error) {
           console.log(error);
         }
       });
   }
  

当我ng serve我的应用程序时，我收到以下错误：

ERROR in ./~/neo4j-driver/lib/v1/internal/ch-node.js
Module not found: Error: Can't resolve 'net' in 'E:\emek\node_modules\neo4j-driver\lib\v1\internal'
 @ ./~/neo4j-driver/lib/v1/internal/ch-node.js 32:11-25 364:2-24
 @ ./~/neo4j-driver/lib/v1/internal/connector.js
 @ ./~/neo4j-driver/lib/v1/driver.js
 @ ./~/neo4j-driver/lib/v1/index.js
 @ ./~/neo4j-driver/lib/index.js
 @ ./src/app/services/heroes.service.ts
 @ ./src/app/app.component.ts
 @ ./src/app/index.ts
 @ ./src/main.ts
 @ multi main

ERROR in ./~/neo4j-driver/lib/v1/internal/ch-node.js
Module not found: Error: Can't resolve 'tls' in 'E:\emek\node_modules\neo4j-driver\lib\v1\internal'
 @ ./~/neo4j-driver/lib/v1/internal/ch-node.js 36:11-25
 @ ./~/neo4j-driver/lib/v1/internal/connector.js
 @ ./~/neo4j-driver/lib/v1/driver.js
 @ ./~/neo4j-driver/lib/v1/index.js
 @ ./~/neo4j-driver/lib/index.js
 @ ./src/app/services/heroes.service.ts
 @ ./src/app/app.component.ts
 @ ./src/app/index.ts
 @ ./src/main.ts
 @ multi main

ERROR in ./~/neo4j-driver/lib/v1/internal/ch-node.js
Module not found: Error: Can't resolve 'readline' in 'E:\emek\node_modules\neo4j-driver\lib\v1\internal'
 @ ./~/neo4j-driver/lib/v1/internal/ch-node.js 92:2-21
 @ ./~/neo4j-driver/lib/v1/internal/connector.js
 @ ./~/neo4j-driver/lib/v1/driver.js
 @ ./~/neo4j-driver/lib/v1/index.js
 @ ./~/neo4j-driver/lib/index.js
 @ ./src/app/services/heroes.service.ts
 @ ./src/app/app.component.ts
 @ ./src/app/index.ts
 @ ./src/main.ts
 @ multi main

angular-cli: 1.0.0-beta.15 节点：4.5.0 操作系统：win32 x64

Answer 1

这可能有点晚了，但无论如何。

首先，您需要更改导入和分配驱动程序的方式。 变化：

import 'neo4j-driver/lib/browser/neo4j-web';

收件人：

import * as neo4j_driver from 'neo4j-driver/lib/browser/neo4j-web.min.js';

然后更改节点查找语法：

var neo4j = require('neo4j-driver').v1;

收件人：

const neo4j = neo4j_driver.v1;

这将消除您遇到的错误。

那么您实际上可能会因为未在 uri 中分配端口而收到错误消息。为了获得正确的端口（7474 对我不起作用），我启动了数据库并在 localhost:7474 访问 Neo4j 浏览器。然后，您必须查看显示“您以用户 neo4j 身份连接的页面” 到服务器 bolt://localhost:7687" 我不确定这是默认设置还是已分配，但无论如何。

然后我在我的 uri 中使用了该端口，现在一切都在 Angular 内部工作了（尽管如果使用远程连接（例如 Graphene）并且我能找到的唯一文档不适用于 JS 驱动程序，我无法让它工作)。

这是我的完整解决方案：

import {Component, OnInit} from '@angular/core';
import * as neo4j_driver from 'neo4j-driver/lib/browser/neo4j-web.min.js';

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent implements OnInit {
  title = 'app works!';

  constructor() {
  }

  ngOnInit() {
    const neo4j = neo4j_driver.v1;
    const uri = 'bolt://localhost:7687';
    const user = 'neo4j';
    const password = '<your password>';
    const driver = neo4j.driver(uri, neo4j.auth.basic(user, password), {maxTransactionRetryTime: 15000});

    // Register a callback to know if driver creation was successful:
    driver.onCompleted = function () {
    // proceed with using the driver, it was successfully instantiated
    };
    // Register a callback to know if driver creation failed.
    // This could happen due to wrong credentials or database unavailability:
    driver.onError = function (error) {
      console.log('Driver instantiation failed', error);
    };

    const session = driver.session();
    const result = session.run('MATCH (a:Person) RETURN a.name ORDER BY a.name');
    const people = [];

    result.subscribe({
      onNext: record => {
        const name = record.get(0);
        people.push(name);
      },
      onCompleted: () => {
        session.close();
        console.log(people);
      },
      onError: error => {
        console.log(error);
      }
    });
  }
}