NestJS+TypeScript+TypeORM迁移报错：无法在模块外使用import语句

报错信息 #

执行迁移时出现如下错误，仅能创建迁移，无法生成或运行：

> @punch-list-api/source@0.0.0 migration:run
> npm run typeorm migration:run


> @punch-list-api/source@0.0.0 typeorm
> typeorm-ts-node-commonjs -d ./ormconfig.ts migration:run

Error during migration run:
Error: Unable to open file: "path of the ormconfig". Cannot use import statement outside a module
    at Function.loadDataSource (/home/snuc/Documents/IOET_TT_Projects/punch-list-api/node_modules/src/commands/CommandUtils.ts:22:19)
    at async Object.handler (/home/snuc/Documents/IOET_TT_Projects/punch-list-api/node_modules/src/commands/MigrationRunCommand.ts:42:26)

当前配置文件 #

ormconfig.ts #

import { DataSource } from 'typeorm';

const connectionSource = new DataSource({
  type: 'postgres',
  host: process.env.RDS_HOSTNAME,
  port: parseInt(process.env.RDS_PORT || '5432'),
  username: process.env.RDS_USERNAME,
  password: process.env.RDS_PASSWORD,
  database: process.env.RDS_DB_NAME,
  entities: [__dirname + '/dist/**/*.entity.js'],
  migrations: [__dirname + '/dist/database/migrations/*.js'],
});

export default connectionSource;

package.json 脚本 #

"typeorm": "typeorm-ts-node-commonjs -d ./ormconfig.ts",
"migration:create": "typeorm-ts-node-commonjs migration:create",
"migration:generate": "npm run typeorm migration:generate",
"migration:run": "npm run typeorm migration:run"

tsconfig.json #

{
  "compilerOptions": {
    "rootDir": ".",
    "sourceMap": true,
    "declaration": false,
    "moduleResolution": "node",
    "emitDecoratorMetadata": true,
    "experimentalDecorators": true,
    "importHelpers": true,
    "target": "es2015",
    "module": "esnext",
    "lib": [
      "es2020",
      "dom"
    ],
    "skipLibCheck": true,
    "skipDefaultLibCheck": true,
    "baseUrl": ".",
    "paths": {},
    "esModuleInterop": true,
    "resolveJsonModule": true
  },
  "files": [],
  "include": [],
  "references": [
    {
      "path": "./tsconfig.app.json"
    },
    {
      "path": "./tsconfig.spec.json"
    }
  ],
  "exclude": [
    "node_modules",
    "tmp"
  ]
}

问题原因 #

核心错误Cannot use import statement outside a module是因为：

• 使用的typeorm-ts-node-commonjs命令强制以CommonJS模块模式加载代码
• 但ormconfig.ts使用了ES模块的import/export语法，同时主tsconfig.json的module设置为esnext，导致模块加载机制冲突

解决方案 #

方案一：修改ormconfig.ts为CommonJS导出 #

将ormconfig.ts的导出方式替换为CommonJS格式，ts-node会自动编译ES模块语法为CommonJS：

import { DataSource } from 'typeorm';

const connectionSource = new DataSource({
  type: 'postgres',
  host: process.env.RDS_HOSTNAME,
  port: parseInt(process.env.RDS_PORT || '5432'),
  username: process.env.RDS_USERNAME,
  password: process.env.RDS_PASSWORD,
  database: process.env.RDS_DB_NAME,
  entities: [__dirname + '/dist/**/*.entity.js'],
  migrations: [__dirname + '/dist/database/migrations/*.js'],
});

// 替换export default为module.exports
module.exports = connectionSource;

方案二：切换为ES模块模式运行TypeORM #

如果希望保留ES模块语法，按以下步骤调整：

1. 在package.json中添加"type": "module"声明
2. 修改ormconfig.ts，手动获取__dirname（ES模块中默认不提供）：

import { DataSource } from 'typeorm';
import { fileURLToPath } from 'url';
import { dirname } from 'path';

const __filename = fileURLToPath(import.meta.url);
const __dirname = dirname(__filename);

const connectionSource = new DataSource({
  type: 'postgres',
  host: process.env.RDS_HOSTNAME,
  port: parseInt(process.env.RDS_PORT || '5432'),
  username: process.env.RDS_USERNAME,
  password: process.env.RDS_PASSWORD,
  database: process.env.RDS_DB_NAME,
  entities: [__dirname + '/dist/**/*.entity.js'],
  migrations: [__dirname + '/dist/database/migrations/*.js'],
});

export default connectionSource;

3. 更新package.json中的脚本，使用ES模块版本的命令：

"typeorm": "typeorm-ts-node-esm -d ./ormconfig.ts",
"migration:create": "typeorm-ts-node-esm migration:create",
"migration:generate": "npm run typeorm migration:generate",
"migration:run": "npm run typeorm migration:run"

方案三：为TypeORM命令单独配置tsconfig #

创建tsconfig-cli.json文件，继承主配置并指定CommonJS模块：

{
  "extends": "./tsconfig.json",
  "compilerOptions": {
    "module": "commonjs",
    "target": "es2017"
  },
  "include": ["ormconfig.ts"]
}

然后更新package.json中的TypeORM脚本，指定使用该配置文件：

"typeorm": "typeorm-ts-node-commonjs -d ./ormconfig.ts --tsconfig ./tsconfig-cli.json",

内容的提问来源于stack exchange，提问作者Freddy Valverde Gallardo