Express の POST request

Last article yes Express In dealing with GET request . Here we'll see how to express In dealing with POST request .

To move to POST, The most important thing is that GET More requests Request body . The key is how to get POST The body of the request . stay express in , Handle POST Request needs to use post() function .

The type of the request body is determined by Content-Type The request header specifies ,POST Common request body types for requests are

• application/x-www-form-urlencoded： The data is encoded as & Separated key value pairs , At the same time = Separate key and value . Characters that are not letters or numbers will be Percentage coding , Also known as URL code .
  
  You can see that the Chinese in the request body is encoded by a percentage . Because of the percentage code , This makes this type of request body unable to send binary data , Therefore, when uploading files , Use only the following multipart/form-data Type substitution
• multipart/form-data： If you want to send this type of request body , Required form method The attribute is POST And enctype The attribute is multipart/form-data. Of course , This type of request body can also exclude binary data , It can be just a simple form .

<form action="http://localhost:3000/login" method="post" enctype="multipart/form-data">
   <input type="text" name="username" placeholder=" full name "/><br>
   <input type="password" name="password" placeholder=" password "/><br>
   <input type="file" name="file" id="file"><br>
   <button type="submit"> Submit </button>
 </form>

• application/json： Now the more common type is JSON Type , You can usually add charset=utf-8; Specify the encoding of the request body .

middleware

In order to make express Have the ability to handle POST The ability to ask , We need to use middleware app.use().

app.use(express.urlencoded({
    
  extended: false
}));
app.use(express.json());

express.urlencoded() and express.json() All are express Built-in middleware . Separately for processing application/x-www-form-urlencoded and application/json Request body of type . among {extended: false} Representation resolution URL code When using querystring library , Instead, use qs library .

Get request parameters

Use req.body Get the request body

app.post('/login', (req, res) => {
    
  let {
     username, password } = req.body;
  console.log('username: ', username);
  console.log('password: ', password);
  res.json(req.body);
});