ExpressJS - RESTful API

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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始终需要 API。关于如何构建和命名这些 API 和端点的流行架构风格称为REST（表述性传输状态）。HTTP 1.1的设计牢记 REST 原则。REST 是由Roy Fielding于 2000 年在他的 Paper Fielding 论文中引入的。

RESTful URI 和方法为我们提供了处理请求所需的几乎所有信息。下表总结了各种动词的使用方式以及 URI 的命名方式。我们将在最后创建一个电影 API；现在让我们讨论如何构建它。

现在让我们在 Express 中创建这个 API。我们将使用 JSON 作为传输数据格式，因为它很容易在 JavaScript 中使用，并且具有其他优点。将您的index.js文件替换为movies.js文件，如以下程序所示。

索引.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，让我们集中精力创建 API。

首先设置 movie.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；所以每次服务器重启时，我们添加的电影就会消失。这可以很容易地使用数据库或文件（使用节点 fs 模块）来模仿。

导入 Express 后，创建一个 Router 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;

获取路线

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}]

我们有一条获取所有电影的路线。现在让我们创建一个路由来通过 ID 获取特定电影。

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 为我们获取电影。要检查输出，请在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

您将得到以下响应 -

{"id":101,"name":"Fight Club","year":1999,"rating":8.1}

如果您访问无效的路由，则会产生“cannot GET”错误，而如果您访问 ID 不存在的有效路由，则会产生 404 错误。

我们已经完成了 GET 路由，现在让我们继续讨论POST路由。

邮政路线

使用以下路由来处理POSTed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});
   }
});

这将创建一部新电影并将其存储在电影变量中。要检查此路线，请在终端中输入以下代码 -

curl -X POST --data "name = Toy%20story&year = 1995&rating = 8.5" http://localhost:3000/movies

将显示以下响应 -

{"message":"New movie created.","location":"/movies/105"}

要测试是否已将其添加到 movie 对象，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。

放置路线

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。按照以下方式创建路线。

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});
      }
   }
});

该路由将执行上表中指定的功能。如果对象存在，它将用新的详细信息更新该对象。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。要创建新电影，只需将 id 更改为不存在的 id 即可。

curl -X PUT --data "name = Toy%20story&year = 1995&rating = 8.5" 
http://localhost:3000/movies/101

回复

{"message":"Movie id 101 updated.","location":"/movies/101"}

删除路线

使用以下代码创建删除路由。-

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."});
   }
});

以与检查其他路线相同的方式检查该路线。成功删除后（例如 id 105），您将得到以下输出 -

{message: "Movie id 105 removed."}

最后，我们的movie.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;

这样就完成了我们的 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。