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  ExpressJS RESTFul API

  • RESTFul API

    创建移动应用程序，单页应用程序，使用AJAX调用并向客户端提供数据始终需要API。关于如何构造和命名这些API和端点的一种流行的体系结构样式称为REST（代表性传输状态）。HTTP 1.1的设计考虑了REST原则。REST由Roy Fielding于2000年在他的Paper Fielding论文中介绍。RESTful URI和方法为我们提供了处理请求所需的几乎所有信息。下表列出了应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。现在让我们讨论它的结构。
    Method URI Details Function
    get /movies 安全，可携带 获取所有电影及其详细信息的列表
    get /movies/1234 安全，可携带 获取电影ID 1234的详细信息
    post /movies 不适用 使用提供的详细信息创建新电影。响应包含此新创建资源的URI。
    put /movies/1234 等幂的 修改电影ID 1234（如果尚不存在，则创建一个）。响应包含此新创建资源的URI。
    delete /movies/1234 等幂的 电影ID 1234（如果存在）应删除。响应应包含请求的状态。
    delete或put /movies 无效 应该是无效的。DELETE和PUT应该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作为传输数据格式，因为它很容易在JavaScript中使用并具有其他好处。 
    
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);
    现在我们已经建立了应用程序，让我们集中精力创建API。首先设置movies.js文件。我们不是使用数据库来存储电影，而是将它们存储在内存中；因此，每当服务器重新启动时，我们添加的电影都会消失。可以使用数据库或文件（使用node fs模块）轻松地模拟它。一旦导入Express，然后创建一个路由器，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}
];

//路由都定义到这里来
module.exports = router;

router.get('/', function(req, res){
    res.json(movies);
 });

  • 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);
});
    要测试是否可以正常运行，我们这里介绍一款HTTP请求工具POSTman，下载安装它。-
    这时候我们测试GET http://localhost:3000/movies，等到如下所示
    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}]
    我们有一条路由来获取所有电影。现在让我们创建一条通过ID来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"});
   }
});
    下图获取id为101的电影的示例：

  • POST 路由

    使用以下路由来处理POST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});
   }
});
    这将创建一个新电影并将其存储在movies变量中。要检查此路由，用设置三个参数（name,year,rating）的请求体，用POST请求URL：http://localhost:3000/movies -

  • PUT 路由

    PUT路由与POST路由几乎相同。我们将为将要更新/创建的对象指定ID。通过以下方式创建路由。- 
    
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函数。如果存在，它将使用新的详细信息更新对象。如果不存在，它将创建一个新对象。要检查路由，这将更新现有电影。要创建新的电影，只需将ID更改为不存在的ID。
    下图我们把id为101的电影进行更改
    下图我们把添加id为1001的电影

  • DELETE 路由

    使用以下代码创建DELETE路由- 
    
router.delete('/:id', function(req, res){
   var removeIndex = movies.map(function(movie){
      return movie.id;
   }).indexOf(parseInt(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."});
   }
});
    DELETE请求http://localhost:3000/103 成功删除后（例如id 103），您将获得以下输出-
    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}
];


// 获取所有电影
router.get('/', function(req, res){
    res.json(movies);
 });

// 根据id获取电影
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"});
    }
 });

// 添加一条电影
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 {
       // 最新的id等于最后一条记录的id+1
       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});
    }
 });

 // 根据id更新电影,id 没有就创建
 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});
       }
    }
 });

 // 删除电影
 router.delete('/:id', function(req, res){
    var removeIndex = movies.map(function(movie){
       return movie.id;
    }).indexOf(parseInt(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，您可以使用此简单的体系结构样式和Express创建更复杂的应用程序。
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