无法通过PHP Client连接Neo4j 4.1.12的问题排查求助

运行Neo4j 4.1.12版本，可通过浏览器使用登录凭证经Bolt连接成功。使用neo4j-php-client编写代码如下：

public function __construct($table = null){
    $config = config('Database')->neo4j;

    if (!empty($config['Username'])){
        $auth = Authenticate::basic($config['Username'],$config['Password']);
    } else {
        $auth = null;
    }

    $this->transact = $config['Transact']; // 配置是否启用事务功能

    $this->client = ClientBuilder::create()->withDriver('bolt','bolt://neo4j:PW_THAT_WORKS@localhost:7687')->build();

    $this->table = $table;
}

public function query($query,$params = []){
    $client = $this->client;
    $statement = new Statement($query,$params);

    if ($this->transact){
        $result = $client->writeTransaction(static function (TransactionInterface $tsx) use ($statement) {
            return $tsx->runStatement($statement);
        });
    } else {
        $result = $client->runStatement($statement);
    }

    return $result;
}

public function insert($data = null, bool $returnID = true){
    if (empty($this->table)){
        return false;
    }

    $result = $this->query('CREATE ('.$this->table. ')');

    print'<pre>';print_r($result);print'</pre>';
}

调用以下代码时：

$neo4j = new \App\Models\Neo4jModel('n:Test');
$neo4j->insert(array('Hello'=>'World','Foobar'=>'Baz'));

出现连接错误：Cannot connect to any server on alias: bolt with Uris: ('bolt://neo4j:PW_THAT_WORKS@localhost:7687')。

但在Neo4j命令行执行CREATE (n:Test)可正常完成，返回Added 1 label, created 1 node, completed after 408 ms.。尝试改用HTTP驱动时，抛出Http\Discovery\Exception\DiscoveryFailedException异常。通过curl访问localhost:7474可正常获取服务信息：

curl localhost:7474 { "bolt_routing" : "neo4j://localhost:7687", "transaction" : "http://localhost:7474/db/{databaseName}/tx", "bolt_direct" : "bolt://localhost:7687", "neo4j_version" : "4.1.12", "neo4j_edition" : "community" }

1. Bolt连接认证方式错误 #

代码中已构建$auth认证对象，但创建Client时未传入，而是直接在URI内嵌用户名密码。Neo4j 4.x版本配合neo4j-php-client时，推荐通过withDriver的第三个参数传入认证对象，而非URI内嵌。

修改Client初始化代码：

$this->client = ClientBuilder::create()
    ->withDriver('bolt', 'bolt://localhost:7687', $auth)
    ->build();

2. HTTP驱动依赖缺失 #

Http\Discovery\Exception\DiscoveryFailedException异常通常是因为缺少PHP HTTP客户端适配器。执行以下命令安装所需依赖：

composer require php-http/guzzle6-adapter

3. 未使用传入的节点属性数据 #

insert方法接收了$data参数，但实际执行的Cypher语句未使用该参数，导致创建节点时无法设置属性。同时应使用参数化查询避免注入风险，修改insert方法：

public function insert($data = null, bool $returnID = true){
    if (empty($this->table) || empty($data)){
        return false;
    }

    // 拆分变量名与标签，处理传入的'n:Test'格式
    preg_match('/^(\w+):(\w+)$/', $this->table, $matches);
    $varName = $matches[1] ?? 'n';
    $label = $matches[2] ?? '';
    if (empty($label)) return false;

    // 构造参数化Cypher语句
    $query = "CREATE ($varName:$label) SET $varName = \$data";
    if ($returnID) {
        $query .= " RETURN ID($varName) as nodeId";
    }
    $result = $this->query($query, ['data' => $data]);

    print'<pre>';print_r($result);print'</pre>';
}

4. 检查PHP环境的Bolt依赖扩展 #

neo4j-php-client的Bolt驱动依赖ext-sockets扩展。通过php -m命令查看是否已安装，若未安装，需在php.ini中添加extension=sockets并重启PHP服务。

内容的提问来源于stack exchange，提问作者Antony