React，获取无法代理请求错误

Question

有一个应用程序。安装的模块和依赖项。但是当我尝试启动应用程序时，API 不起作用 - 它会写入代理错误。 (

Proxy error: Could not proxy request

).

我在网上翻遍了一堆东西，en.stackover上有一篇文章，但是该死的，我似乎一切都做对了，但结果是一样的。我无法理解。

我的package.json文件：

{
  "name": "app",
  "version": "0.1.0",
  "private": true,
  "dependencies": {
    "@babel/core": "7.12.3",
    "@pmmmwh/react-refresh-webpack-plugin": "0.4.2",
    "@svgr/webpack": "5.4.0",
    "@testing-library/jest-dom": "^5.11.6",
    "@testing-library/react": "^11.2.2",
    "@testing-library/user-event": "^12.2.2",
    "@typescript-eslint/eslint-plugin": "^4.5.0",
    "@typescript-eslint/parser": "^4.5.0",
    "babel-eslint": "^10.1.0",
    "babel-jest": "^26.6.0",
    "babel-loader": "8.1.0",
    "babel-plugin-named-asset-import": "^0.3.7",
    "babel-preset-react-app": "^10.0.0",
    "bfj": "^7.0.2",
    "camelcase": "^6.1.0",
    "case-sensitive-paths-webpack-plugin": "2.3.0",
    "chokidar": "^3.5.2",
    "css-loader": "4.3.0",
    "datatables.net": "^1.10.23",
    "datatables.net-dt": "^1.10.23",
    "dotenv": "8.2.0",
    "dotenv-expand": "5.1.0",
    "eslint": "^7.11.0",
    "eslint-config-react-app": "^6.0.0",
    "eslint-plugin-flowtype": "^5.2.0",
    "eslint-plugin-import": "^2.22.1",
    "eslint-plugin-jest": "^24.1.0",
    "eslint-plugin-jsx-a11y": "^6.3.1",
    "eslint-plugin-react": "^7.21.5",
    "eslint-plugin-react-hooks": "^4.2.0",
    "eslint-plugin-testing-library": "^3.9.2",
    "eslint-webpack-plugin": "^2.1.0",
    "express": "^4.17.1",
    "file-loader": "6.1.1",
    "fs-extra": "^9.0.1",
    "html-webpack-plugin": "4.5.0",
    "identity-obj-proxy": "3.0.0",
    "inputmask": "^5.0.5",
    "jest": "26.6.0",
    "jest-circus": "26.6.0",
    "jest-resolve": "26.6.0",
    "jest-watch-typeahead": "0.6.1",
    "jquery": "^3.5.1",
    "lightbox2": "^2.11.3",
    "mini-css-extract-plugin": "0.11.3",
    "optimize-css-assets-webpack-plugin": "5.0.4",
    "pnp-webpack-plugin": "1.6.4",
    "postcss-flexbugs-fixes": "4.2.1",
    "postcss-loader": "3.0.0",
    "postcss-normalize": "8.0.1",
    "postcss-preset-env": "6.7.0",
    "postcss-safe-parser": "5.0.2",
    "prompts": "2.4.0",
    "react": "^17.0.2",
    "react-app-polyfill": "^2.0.0",
    "react-data-table-component": "^7.0.0-alpha-5",
    "react-dev-utils": "^11.0.1",
    "react-dom": "^17.0.2",
    "react-input-mask": "^2.0.4",
    "react-input-range": "^1.3.0",
    "react-refresh": "^0.8.3",
    "react-router-dom": "^5.2.0",
    "resolve": "1.18.1",
    "resolve-url-loader": "^3.1.2",
    "sass-loader": "8.0.2",
    "semver": "7.3.2",
    "slick-carousel": "^1.8.1",
    "style-loader": "1.3.0",
    "styled-components": "^5.3.0",
    "terser-webpack-plugin": "4.2.3",
    "ts-pnp": "1.2.0",
    "url-loader": "4.1.1",
    "webpack": "4.44.2",
    "webpack-dev-server": "3.11.0",
    "webpack-manifest-plugin": "2.2.0",
    "workbox-webpack-plugin": "5.1.4"
  },
  "scripts": {
    "start": "node --max-http-header-size=14120024 --max-old-space-size=20096 scripts/start.js",
    "build": "node scripts/build.js",
    "test": "node scripts/test.js"
  },
  "eslintConfig": {
    "extends": [
      "react-app",
      "react-app/jest"
    ]
  },
  "browserslist": {
    "production": [
      ">0.2%",
      "not dead",
      "not op_mini all"
    ],
    "development": [
      "last 1 chrome version",
      "last 1 firefox version",
      "last 1 safari version"
    ]
  },
  "proxy": "http://localhost:3000/",
  "jest": {
    "roots": [
      "<rootDir>/src"
    ],
    "collectCoverageFrom": [
      "src/**/*.{js,jsx,ts,tsx}",
      "!src/**/*.d.ts"
    ],
    "setupFiles": [
      "react-app-polyfill/jsdom"
    ],
    "setupFilesAfterEnv": [],
    "testMatch": [
      "<rootDir>/src/**/__tests__/**/*.{js,jsx,ts,tsx}",
      "<rootDir>/src/**/*.{spec,test}.{js,jsx,ts,tsx}"
    ],
    "testEnvironment": "jsdom",
    "testRunner": "/Users/user/Downloads/goroskop2/node_modules/jest-circus/runner.js",
    "transform": {
      "^.+\\.(js|jsx|mjs|cjs|ts|tsx)$": "<rootDir>/node_modules/babel-jest",
      "^.+\\.css$": "<rootDir>/config/jest/cssTransform.js",
      "^(?!.*\\.(js|jsx|mjs|cjs|ts|tsx|css|json)$)": "<rootDir>/config/jest/fileTransform.js"
    },
    "transformIgnorePatterns": [
      "[/\\\\]node_modules[/\\\\].+\\.(js|jsx|mjs|cjs|ts|tsx)$",
      "^.+\\.module\\.(css|sass|scss)$"
    ],
    "modulePaths": [],
    "moduleNameMapper": {
      "^react-native$": "react-native-web",
      "^.+\\.module\\.(css|sass|scss)$": "identity-obj-proxy"
    },
    "moduleFileExtensions": [
      "web.js",
      "js",
      "web.ts",
      "ts",
      "web.tsx",
      "tsx",
      "json",
      "web.jsx",
      "jsx",
      "node"
    ],
    "watchPlugins": [
      "jest-watch-typeahead/filename",
      "jest-watch-typeahead/testname"
    ],
    "resetMocks": true
  },
  "babel": {
    "presets": [
      "react-app"
    ]
  }
}

项目结构：

-api
-config 
-node_modules 
-public
-scripts 
-src 
-upload
-vendor
package.json 
package-lock.json

如果有人可以建议我将非常感激。到目前为止我尝试过的：

放入代理
http:// 本地主机
http:// 本地主机 /
http:// 本地主机: 3000
http:// 本地主机: 3000 /

运行serve -s build。

在本例中，它在端口 3000 上运行，当应用程序启动时，通过 API 访问时，它会发出一个 html 页面（来自构建目录）

我还尝试分别运行nodescripts/start.js和npmstart。
按计划 - 结果是无稽之谈，但我已经尝试了一切。

Answer 1

对于处理请求的代理，您调用的端点不应由您的 React 开发服务器处理。例如，您的 API 应该类似于

fetch('/')

，而不是发送 React

index.html

文件的端点

fetch('/api/')

。

就像医生说：

要告诉开发服务器将任何未知请求代理到开发中的 API 服务器，请在

proxy

中添加

package.json

字段，例如：

"proxy": "http://localhost:8080"

。

这样，当您

fetch('/api/todos')

进行开发时，开发服务器会识别出它不是静态资产，并将您的请求代理到

http://localhost:8080/api/todos

作为后备。开发服务器只会尝试将其

text/html

标头中没有

Accept

的请求发送到代理。

如果还是不行，你可以切换到手动配置代理，这是创建React App谈到的第二种设置代理的方法。

为此，首先，删除

proxy

中的

package.json

，保留它，因为这是我上面谈到的端点的规则，然后：

npm install http-proxy-middleware --save-dev

最后，创建一个

src/setupProxy.js

文件：

const { createProxyMiddleware } = require('http-proxy-middleware');

module.exports = function(app) {
  app.use(
    '/api', // 👈🏽 your API endpoint goes here.
    createProxyMiddleware({
      target: 'http://localhost:8080', // 👈🏽 your API URL goes here.
      changeOrigin: true,
    })
  );
};