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- ExpressJS 教程
- ExpressJS - 首页
- ExpressJS - 概述
- ExpressJS - 环境
- ExpressJS - Hello World
- ExpressJS - 路由
- ExpressJS - HTTP 方法
- ExpressJS - URL 构建
- ExpressJS - 中间件
- ExpressJS - 模板引擎
- ExpressJS - 静态文件
- ExpressJS - 表单数据
- ExpressJS - 数据库
- ExpressJS - Cookie
- ExpressJS - Session
- ExpressJS - 身份验证
- ExpressJS - RESTful API
- ExpressJS - 脚手架
- ExpressJS - 错误处理
- ExpressJS - 调试
- ExpressJS - 最佳实践
- ExpressJS - 资源
- ExpressJS 有用资源
- ExpressJS - 快速指南
- ExpressJS - 有用资源
- ExpressJS - 讨论
ExpressJS - RESTful API
创建移动应用程序、单页应用程序、使用 AJAX 调用以及向客户端提供数据时,始终需要 API。一种关于如何构建和命名这些 API 及其端点的流行架构风格称为 **REST(具象状态传输)**。**HTTP 1.1** 的设计就考虑了 REST 原则。REST 由 **Roy Fielding** 于 2000 年在其论文 Fielding Dissertations 中提出。
RESTful URI 和方法为我们提供了处理请求所需的大部分信息。下表总结了如何使用各种动词以及如何命名 URI。我们将在最后创建一个电影 API;现在让我们讨论一下它的结构。
方法 | URI | 细节 | 功能 |
---|---|---|---|
GET | /movies | 安全,可缓存 | 获取所有电影及其详细信息的列表 |
GET | /movies/1234 | 安全,可缓存 | 获取电影 ID 1234 的详细信息 |
POST | /movies | N/A | 使用提供的详细信息创建一个新的电影。响应包含此新创建资源的 URI。 |
PUT | /movies/1234 | 幂等 | 修改电影 ID 1234(如果不存在则创建一个)。响应包含此新创建资源的 URI。 |
DELETE | /movies/1234 | 幂等 | 如果存在,则应删除电影 ID 1234。响应应包含请求的状态。 |
DELETE 或 PUT | /movies | 无效 | 应为无效。**DELETE** 和 **PUT** 应指定它们正在处理的资源。 |
现在让我们在 Express 中创建此 API。我们将使用 JSON 作为我们的传输数据格式,因为它易于在 JavaScript 中使用并且具有其他优点。将您的 **index.js** 文件替换为以下程序中的 **movies.js** 文件。
index.js
var express = require('express'); var bodyParser = require('body-parser'); var multer = require('multer'); var upload = multer(); var app = express(); app.use(cookieParser()); app.use(bodyParser.json()); app.use(bodyParser.urlencoded({ extended: true })); app.use(upload.array()); //Require the Router we defined in movies.js var movies = require('./movies.js'); //Use the Router on the sub route /movies app.use('/movies', movies); app.listen(3000);
现在我们已经设置了应用程序,让我们专注于创建 API。
首先设置 movies.js 文件。我们没有使用数据库来存储电影,而是将它们存储在内存中;因此,每次服务器重启时,我们添加的电影都会消失。这可以通过使用数据库或文件(使用 node fs 模块)轻松模拟。
导入 Express 后,创建一个路由器并使用module.exports导出它 -
var express = require('express'); var router = express.Router(); var movies = [ {id: 101, name: "Fight Club", year: 1999, rating: 8.1}, {id: 102, name: "Inception", year: 2010, rating: 8.7}, {id: 103, name: "The Dark Knight", year: 2008, rating: 9}, {id: 104, name: "12 Angry Men", year: 1957, rating: 8.9} ]; //Routes will go here module.exports = router;
GET 路由
让我们定义获取所有电影的 GET 路由 -
router.get('/', function(req, res){ res.json(movies); });
要测试这是否正常工作,请运行您的应用程序,然后打开您的终端并输入 -
curl -i -H "Accept: application/json" -H "Content-Type: application/json" -X GET localhost:3000/movies
将显示以下响应 -
[{"id":101,"name":"Fight Club","year":1999,"rating":8.1}, {"id":102,"name":"Inception","year":2010,"rating":8.7}, {"id":103,"name":"The Dark Knight","year":2008,"rating":9}, {"id":104,"name":"12 Angry Men","year":1957,"rating":8.9}]
我们有一个获取所有电影的路由。现在让我们创建一个通过其 ID 获取特定电影的路由。
router.get('/:id([0-9]{3,})', function(req, res){ var currMovie = movies.filter(function(movie){ if(movie.id == req.params.id){ return true; } }); if(currMovie.length == 1){ res.json(currMovie[0]) } else { res.status(404);//Set status to 404 as movie was not found res.json({message: "Not Found"}); } });
这将根据我们提供的 ID 获取电影。要检查输出,请在您的终端中使用以下命令 -
curl -i -H "Accept: application/json" -H "Content-Type: application/json" -X GET localhost:3000/movies/101
您将获得以下响应 -
{"id":101,"name":"Fight Club","year":1999,"rating":8.1}
如果您访问无效路由,它将产生一个 **无法获取错误**,而如果您访问具有不存在 ID 的有效路由,它将产生一个 404 错误。
我们完成了 GET 路由,现在让我们继续 **POST** 路由。
POST 路由
使用以下路由处理 **POST** 的数据 -
router.post('/', function(req, res){ //Check if all fields are provided and are valid: if(!req.body.name || !req.body.year.toString().match(/^[0-9]{4}$/g) || !req.body.rating.toString().match(/^[0-9]\.[0-9]$/g)){ res.status(400); res.json({message: "Bad Request"}); } else { var newId = movies[movies.length-1].id+1; movies.push({ id: newId, name: req.body.name, year: req.body.year, rating: req.body.rating }); res.json({message: "New movie created.", location: "/movies/" + newId}); } });
这将创建一个新的电影并将其存储在 movies 变量中。要检查此路由,请在您的终端中输入以下代码 -
curl -X POST --data "name = Toy%20story&year = 1995&rating = 8.5" https://127.0.0.1:3000/movies
将显示以下响应 -
{"message":"New movie created.","location":"/movies/105"}
要测试这是否已添加到 movies 对象中,请再次运行 ** /movies/105** 的 get 请求。将显示以下响应 -
{"id":105,"name":"Toy story","year":"1995","rating":"8.5"}
让我们继续创建 PUT 和 DELETE 路由。
PUT 路由
PUT 路由与 POST 路由几乎相同。我们将为要更新/创建的对象指定 ID。以以下方式创建路由。
router.put('/:id', function(req, res){ //Check if all fields are provided and are valid: if(!req.body.name || !req.body.year.toString().match(/^[0-9]{4}$/g) || !req.body.rating.toString().match(/^[0-9]\.[0-9]$/g) || !req.params.id.toString().match(/^[0-9]{3,}$/g)){ res.status(400); res.json({message: "Bad Request"}); } else { //Gets us the index of movie with given id. var updateIndex = movies.map(function(movie){ return movie.id; }).indexOf(parseInt(req.params.id)); if(updateIndex === -1){ //Movie not found, create new movies.push({ id: req.params.id, name: req.body.name, year: req.body.year, rating: req.body.rating }); res.json({message: "New movie created.", location: "/movies/" + req.params.id}); } else { //Update existing movie movies[updateIndex] = { id: req.params.id, name: req.body.name, year: req.body.year, rating: req.body.rating }; res.json({message: "Movie id " + req.params.id + " updated.", location: "/movies/" + req.params.id}); } } });
此路由将执行上表中指定的功能。如果对象存在,它将使用新详细信息更新对象。如果不存在,它将创建一个新对象。要检查路由,请使用以下 curl 命令。这将更新现有的电影。要创建新的电影,只需将 ID 更改为不存在的 ID。
curl -X PUT --data "name = Toy%20story&year = 1995&rating = 8.5" https://127.0.0.1:3000/movies/101
响应
{"message":"Movie id 101 updated.","location":"/movies/101"}
DELETE 路由
使用以下代码创建一个删除路由。-
router.delete('/:id', function(req, res){ var removeIndex = movies.map(function(movie){ return movie.id; }).indexOf(req.params.id); //Gets us the index of movie with given id. if(removeIndex === -1){ res.json({message: "Not found"}); } else { movies.splice(removeIndex, 1); res.send({message: "Movie id " + req.params.id + " removed."}); } });
以与我们检查其他路由相同的方式检查路由。成功删除(例如 ID 105)后,您将获得以下输出 -
{message: "Movie id 105 removed."}
最后,我们的 **movies.js** 文件将如下所示。
var express = require('express'); var router = express.Router(); var movies = [ {id: 101, name: "Fight Club", year: 1999, rating: 8.1}, {id: 102, name: "Inception", year: 2010, rating: 8.7}, {id: 103, name: "The Dark Knight", year: 2008, rating: 9}, {id: 104, name: "12 Angry Men", year: 1957, rating: 8.9} ]; router.get('/:id([0-9]{3,})', function(req, res){ var currMovie = movies.filter(function(movie){ if(movie.id == req.params.id){ return true; } }); if(currMovie.length == 1){ res.json(currMovie[0]) } else { res.status(404); //Set status to 404 as movie was not found res.json({message: "Not Found"}); } }); router.post('/', function(req, res){ //Check if all fields are provided and are valid: if(!req.body.name || !req.body.year.toString().match(/^[0-9]{4}$/g) || !req.body.rating.toString().match(/^[0-9]\.[0-9]$/g)){ res.status(400); res.json({message: "Bad Request"}); } else { var newId = movies[movies.length-1].id+1; movies.push({ id: newId, name: req.body.name, year: req.body.year, rating: req.body.rating }); res.json({message: "New movie created.", location: "/movies/" + newId}); } }); router.put('/:id', function(req, res) { //Check if all fields are provided and are valid: if(!req.body.name || !req.body.year.toString().match(/^[0-9]{4}$/g) || !req.body.rating.toString().match(/^[0-9]\.[0-9]$/g) || !req.params.id.toString().match(/^[0-9]{3,}$/g)){ res.status(400); res.json({message: "Bad Request"}); } else { //Gets us the index of movie with given id. var updateIndex = movies.map(function(movie){ return movie.id; }).indexOf(parseInt(req.params.id)); if(updateIndex === -1){ //Movie not found, create new movies.push({ id: req.params.id, name: req.body.name, year: req.body.year, rating: req.body.rating }); res.json({ message: "New movie created.", location: "/movies/" + req.params.id}); } else { //Update existing movie movies[updateIndex] = { id: req.params.id, name: req.body.name, year: req.body.year, rating: req.body.rating }; res.json({message: "Movie id " + req.params.id + " updated.", location: "/movies/" + req.params.id}); } } }); router.delete('/:id', function(req, res){ var removeIndex = movies.map(function(movie){ return movie.id; }).indexOf(req.params.id); //Gets us the index of movie with given id. if(removeIndex === -1){ res.json({message: "Not found"}); } else { movies.splice(removeIndex, 1); res.send({message: "Movie id " + req.params.id + " removed."}); } }); module.exports = router;
这完成了我们的 REST API。现在您可以使用这种简单的架构风格和 Express 创建更复杂的应用程序。