TypeORM在AWS Lambda中解决实体元数据未找到错误：初始化策略优化

// src/db/data-source.ts (或您的TypeORM数据源定义文件)
import { DataSource } from "typeorm";
import { Silo, SiloLevel, SiloSecondaryKeyword, SiloLevelSiloLevel } from "../classes/Entities"; // 假设您的实体都在这个文件或被正确导出
import { SnakeNamingStrategy } from "typeorm-naming-strategies"; // 如果您使用了命名策略

export const AppDataSource = new DataSource({
    type: "postgres",
    username: process.env.DB_USER,
    host: process.env.DB_HOST,
    database: process.env.DB_NAME,
    password: process.env.DB_PASSWORD,
    port: parseInt(process.env.DB_PORT || "5432", 10),
    entities: [Silo, SiloLevel, SiloSecondaryKeyword, SiloLevelSiloLevel], // 直接引用实体类
    // 如果实体文件是动态加载的，可以考虑使用 glob 模式，但需要确保打包工具正确处理
    // entities: [__dirname + "/../classes/*.ts", __dirname + "/../classes/*.js"],
    namingStrategy: new SnakeNamingStrategy(),
    synchronize: false, // 生产环境通常设置为 false
    logging: false, // 生产环境通常设置为 false
});

// 注意：这里不再立即调用 AppDataSource.initialize()
// 而是将初始化逻辑放到 Lambda handler 中

// src/handlers/my-lambda-handler.ts (您的Lambda主处理函数)
import { APIGatewayProxyEvent, APIGatewayProxyResult, Context } from 'aws-lambda';
import { AppDataSource } from '../db/data-source'; // 导入您的数据源
// import serverlessExpress from '@vendia/serverless-express'; // 如果您使用 serverless-express

// 假设您的业务逻辑函数
async function getSilosService() {
    // 确保数据源已初始化
    if (!AppDataSource.isInitialized) {
        await AppDataSource.initialize();
        console.log("Data Source has been initialized!");
    }
    const siloRepository = AppDataSource.getRepository(Silo); // 假设 Silo 是一个已导入的实体
    return siloRepository.find();
}

export const handler = async (event: APIGatewayProxyEvent, context: Context): Promise<APIGatewayProxyResult> => {
    // 确保数据源已初始化
    if (!AppDataSource.isInitialized) {
        await AppDataSource.initialize();
        console.log("Data Source has been initialized!");
    }

    try {
        // 示例：调用您的业务逻辑
        const silos = await getSilosService(); // 或者直接在这里执行数据库操作
        // const silos = await AppDataSource.getRepository(Silo).find();

        return {
            statusCode: 200,
            headers: { "Content-Type": "application/json" },
            body: JSON.stringify(silos),
        };
    } catch (error) {
        console.error("Error during Lambda execution:", error);
        return {
            statusCode: 500,
            headers: { "Content-Type": "application/json" },
            body: JSON.stringify({ message: "Internal Server Error", error: error.message }),
        };
    }
};

// 如果您使用 serverless-express 或类似框架，可能需要这样封装
// let serverlessExpressInstance;
// async function setup() {
//     const app = require('../app'); // 您的 Express 应用
//     serverlessExpressInstance = serverlessExpress({ app });
// }

// exports.handler = async (event: any, context: any) => {
//     if (!AppDataSource.isInitialized) {
//         await AppDataSource.initialize();
//         console.log("Data Source has been initialized!");
//     }
//     if (!serverlessExpressInstance) {
//         await setup();
//     }
//     return serverlessExpressInstance.proxy(event, context);
// };