Next.js + Mongoose(MongoDB)数据库填充报错求助

问题背景 #

在Next.js项目中编写Mongoose数据库填充脚本seeder.js，配置package.json命令后运行出现多次模块相关错误，以下是问题代码、配置及对应解决方法：

原始代码与配置 #

seeder.js 代码：

import Product from '/models/productModel';
import products from '/data/products';
import dbConnect from '/config/dbConnect';

dbConnect();

const seedProducts = async () => {
  try {
    await Product.deleteMany();
    console.log('Products are deleted');

    await Product.insertMany(products);
    console.log('All Products are added.');

    process.exit();
  } catch (error) {
    console.log(error.message);
    process.exit();
  }
};

seedProducts();

package.json 脚本配置：

"scripts": {
    "dev": "next dev",
    "build": "next build",
    "start": "next start",
    "lint": "next lint",
    "seeder": "node utils/seeder"
  },

错误1：ES模块语法错误 #

报错信息 #

(node:27824) Warning: To load an ES module, set "type": "module" in the package.json or use the .mjs extension.
(Use `node --trace-warnings ...` to show where the warning was created)
C:\Users\tarek\Desktop\Code\utils\seeder.js:1
import Product from '/models/productModel';
^^^^^^

SyntaxError: Cannot use import statement outside a module

解决方法 #

两种方案二选一：

1. 将seeder.js重命名为seeder.mjs（后续需同步更新命令）；
2. 在项目根目录的package.json中添加"type": "module"字段，使整个项目默认使用ES模块：

   {
     "type": "module",
     // 其他原有配置...
   }
   

错误2：模块路径找不到（文件后缀未更新） #

报错信息 #

node:internal/modules/cjs/loader:959
  throw err;
  ^

Error: Cannot find module 'C:\Users\tarek\Desktop\Code\utils\seeder'
    at Module._resolveFilename (node:internal/modules/cjs/loader:956:15)
    at Module._load (node:internal/modules/cjs/loader:804:27)
    at Function.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:81:12)
    at node:internal/main/run_main_module:17:47 {
  code: 'MODULE_NOT_FOUND',
  requireStack: []
}

解决方法 #

因为已经将文件改为seeder.mjs，需要更新package.json中的seeder命令，添加文件后缀：

"scripts": {
    // 其他命令...
    "seeder": "node utils/seeder.mjs"
  },

错误3：导入模块路径错误 #

报错信息 #

Error [ERR_MODULE_NOT_FOUND]: Cannot find module 'C:\models\productModel' imported from C:\Users\tarek\Desktop\Code\utils\seeder.mjs
at new NodeError (node:internal/errors:387:5)
at finalizeResolution (node:internal/modules/esm/resolve:404:11)
at moduleResolve (node:internal/modules/esm/resolve:965:10)
at defaultResolve (node:internal/modules/esm/resolve:1173:11)
at nextResolve (node:internal/modules/esm/loader:173:28)
at ESMLoader.resolve (node:internal/modules/esm/loader:852:30)    at ESMLoader.getModuleJob (node:internal/modules/esm/loader:439:18)
at ModuleWrap. (node:internal/modules/esm/module_job:76:40)
at link (node:internal/modules/esm/module_job:75:36) {
code: 'ERR_MODULE_NOT_FOUND'
}

解决方法 #

Node.js的ES模块中，/开头的路径会被解析为系统根目录（如C:\），而非项目根目录。需要将导入路径改为相对路径，并添加完整文件后缀：
假设项目目录结构为：

项目根目录/
├── models/
│   └── productModel.js
├── data/
│   └── products.js
├── config/
│   └── dbConnect.js
└── utils/
    └── seeder.mjs

修改seeder.mjs中的导入路径：

// 从utils目录往上一级到项目根目录，再指向对应文件
import Product from '../models/productModel.js';
import products from '../data/products.js';
import dbConnect from '../config/dbConnect.js';

完成以上修改后，运行npm run seeder即可正常执行数据库填充脚本。

内容的提问来源于stack exchange，提问作者User_T