nextjs 中未加载 dotenv 值

Question

我正在努力将我的 .env 文件加载到我的 NextJS 应用程序中。这是我的代码：

我的.env 在根目录/
我的index.js 在/pages/index.js

这是我的index.js：

require("dotenv").config({ path: __dirname + '/../.env' })

import React, {Component} from 'react'
import Layout from '../components/layout'
import axios from 'axios'

class Import extends Component{

    uploadCSV = (evt) => {
        evt.preventDefault();

        const uploadURL = process.env.MY_UPLOAD_URL

        let data = new FormData(evt.target)

        axios.post(uploadURL, data, {
            headers: {
                'Content-Type': 'multipart/form-data'
            }
        }).then((res) => {
            console.log(res)
        })
    }

    render() {
        return (
            <div>
                <Layout title="Import Chatbot Intents" description="Import Chatbot Intents">
                    <form onSubmit={this.uploadCSV} name="import_csv" className="import_csv">
                        <h2>Import CSV</h2>
                        <div className="form-group">
                            <label htmlFor="csv_file">Upload file here: </label>
                            <input type="file" name="csv_file" id="csv_file" ref="csv_file" />
                        </div>
                        <div className="form-group">
                            <input type="hidden" id="customer_id" name="customer_id" ref="customer_id" value="1"/>
                            <button className="btn btn-success">Submit</button>
                        </div>
                    </form>
                </Layout>
            </div>
        )
    }
}

export default Import

我观察到我可以在render() 函数中打印出.env 内容，但我不能在uploadCSV 函数中这样做。

供您参考：

• 仅使用 require("dotenv").config() 不起作用
• 使用require("dotenv").config({path: "../"}) 不起作用

更新

我的env-config.js：

module.exports = {
    'CSV_UPLOAD_URL': "http://localhost:3000/uploadcsv"
}

我的 babel.config.js：

const env = require('./env-config')
console.log(env)

module.exports = function(api){

  // console.log({"process": process.env})
  api.cache(false)

  const presets = [
    "next/babel",
    "@zeit/next-typescript/babel"
  ]

  const plugins = [

      "@babel/plugin-transform-runtime",
      [
        'transform-define',
        env
      ]
  ]

  return { presets, plugins }
}

我的package.json

{
  "name": "Botadmin",
  "scripts": {
    "dev": "next -p 3001",
    "build": "next build",
    "start": "next start"
  },
  "dependencies": {
    "@babel/runtime": "^7.1.5",
    "@zeit/next-less": "^1.0.1",
    "@zeit/next-typescript": "^1.1.1",
    "@zeit/next-workers": "^1.0.0",
    "axios": "^0.18.0",
    "forever": "^0.15.3",
    "less": "^3.8.1",
    "multer": "^1.4.1",
    "next": "7.0.2",
    "nprogress": "^0.2.0",
    "papaparse": "^4.6.2",
    "react": "16.6.3",
    "react-dom": "16.6.3",
    "typescript": "^3.1.6",
    "worker-loader": "^2.0.0"
  },
  "devDependencies": {
    "@babel/plugin-transform-runtime": "^7.1.0",
    "babel-plugin-transform-define": "^1.3.0",
    "dotenv": "^6.1.0",
    "fork-ts-checker-webpack-plugin": "^0.4.15"
  }
}

错误：

模块构建失败（来自 ./node_modules/next/dist/build/webpack/loaders/next-babel-loader.js）：

TypeError：MemberExpression 预期节点的属性属性为 ["Identifier","PrivateName"] 类型，但得到的是 "StringLiteral"

Answer 1

我知道我来晚了，但是，您可以安装 dotenv 并在您的 next.config.js 文件中使用它

require("dotenv").config();

const environment = process.env.NODE_ENV || "dev";

Answer 2

从 Next.js 9.4 开始，有一个用于设置环境变量的内置解决方案https://nextjs.org/docs/basic-features/environment-variables

Answer 3

感谢@Alex 的回答。解决相同问题的另一种方法是使用npm install -D dotenv-webpack 安装dotenv-webpack。

安装后。编辑next.config.js:

require('dotenv').config()
const Dotenv = require('dotenv-webpack')

const path = require('path')

const withTypescript = require('@zeit/next-typescript')
const withWorkers = require('@zeit/next-workers')
const withLess = require('@zeit/next-less')

module.exports = withWorkers(withLess(withTypescript({
    context: __dirname,
    generateEtags: false,
    entry: './pages/index.js',
    distDir: 'build',
    pageExtensions: ['js', 'jsx', 'ts', 'tsx'],

    cssModules: false,

    webpack: (config, options) => {

        config.plugins = config.plugins || []

        config.plugins = [
            ...config.plugins,

            // Read the .env file
            new Dotenv({
                path: path.join(__dirname, '.env'),
                systemvars: true
            })
        ]

        // Fixes npm packages that depend on `fs` module
        config.node = {
            fs: 'empty'
        }

        return config
    }
})))

Answer 4

如果你想使用env in Nextjs

1. 安装babel-plugin-transform-define

2. 创建 env-config.js 文件并定义变量

   const prod = process.env.NODE_ENV === 'production'
   module.exports = {
    'process.env.BACKEND_URL': prod ? 'https://api.example.com' : 'https://localhost:8080'
   }
   

3. 创建 .babelrc.js 文件

   const env = require('./env-config.js')
   
   module.exports = {
    presets: ['next/babel'],
    plugins: [['transform-define', env]] 
   }
   

4. 现在您可以访问代码中的环境

    process.env.BACKEND_URL
   

替代方案：next-env