如何将Apache Ignite与NestJS连接？遇构造函数错误求助

错误原因 #

你遇到的TypeError: apache_ignite_client_1.default is not a constructor是因为导入方式不正确。apache-ignite-client库采用命名导出而非默认导出，默认导入会导致无法正确获取构造函数。

修复步骤 #

1. 修正导入语句 #

将默认导入改为命名导入，同时加载所需的类：

import { Injectable } from '@nestjs/common';
import { IgniteClient, SqlFieldsQuery } from 'apache-ignite-client';

2. 修正SqlFieldsQuery实例化代码 #

原代码中new SqlFieldsQuery.query(...)是错误写法，SqlFieldsQuery本身就是构造函数，直接实例化即可：

async getData() {
    // 检查连接状态，避免重复发起连接请求
    if (!this.igniteClient.isConnected()) {
        await this.connect();
    }
    const query = new SqlFieldsQuery("SELECT * FROM alarms");
    const result = await this.igniteClient.query(query);
    return result.getAll();
}

3. 优化连接逻辑（可选） #

每次调用getData都触发connect会导致重复连接，建议在服务初始化时完成连接，或在connect方法中添加状态判断：

constructor() {
    this.igniteClient = new IgniteClient();
    // 初始化阶段自动尝试连接
    this.connect().catch(err => console.error('Ignite连接失败:', err));
}

async connect() {
    if (!this.igniteClient.isConnected()) {
        await this.igniteClient.connect('localhost:10800');
    }
}

完整修复后的代码 #

import { Injectable } from '@nestjs/common';
import { IgniteClient, SqlFieldsQuery } from 'apache-ignite-client';

@Injectable()
export class AlarmsService {

    private igniteClient: IgniteClient;

    constructor() {
        this.igniteClient = new IgniteClient();
        this.connect().catch(err => console.error('Ignite连接异常:', err));
    }
    
    async connect() {
        if (!this.igniteClient.isConnected()) {
            await this.igniteClient.connect('localhost:10800');
        }
    }

    async getData() {
        await this.connect();
        const query = new SqlFieldsQuery("SELECT * FROM alarms");
        const result = await this.igniteClient.query(query);
        return result.getAll();
    }
}

内容的提问来源于stack exchange，提问作者Ajay Kakde