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。

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