Introduction to the use of the Request module in Node.js to handle HTTP protocol requests

This article mainly introduces the basic usage tutorial of the Request module in Node.js to handle HTTP requests. request also supports OAuth signature requests, which is very good and powerful. Friends who need it can refer to it

Here Introducing a Node.js module - request. With this module, http requests become super simple.

Request is super simple to use and supports https and redirection.

var request = require('request');
request('http://www.google.com', function (error, response, body) {
 if (!error && response.statusCode == 200) {
 console.log(body) // 打印google首页
}
})

Stream:

Any response can be output to a file stream.

request('http://google.com/doodle.png').pipe(fs.createWriteStream('doodle.png'))

In turn, you can also pass the file to a PUT or POST request. If no header is provided, the file extension will be detected and the corresponding content-type will be set in the PUT request.

fs.createReadStream('file.json').pipe(request.put('http://mysite.com/obj.json'))
Requests can also be piped to themselves. In this case, the original content-type and content-length will be retained.

request.get('http://google.com/img.png').pipe(request.put('http://mysite.com/img.png'))
Form:

request supports application/x-www-form-urlencoded and multipart/form-data to implement form upload.

x-www-form-urlencoded is simple:

request.post('http://service.com/upload', {form:{key:'value'}})

or:

request.post('http://service.com/upload').form({key:'value'})

When using multipart/form-data, you don’t have to worry about trivial matters such as setting headers. request will help you solve it.

var r = request.post('http://service.com/upload')
var form = r.form()
form.append('my_field', 'my_value')
form.append('my_buffer', new Buffer([1, 2, 3]))
form.append('my_file', fs.createReadStream(path.join(__dirname, 'doodle.png'))
form.append('remote_file', request('http://google.com/doodle.png'))

HTTP authentication:

request.get('http://some.server.com/').auth('username', 'password', false);

or

request.get('http://some.server.com/', {
 'auth': {
 'user': 'username',
 'pass': 'password',
 'sendImmediately': false
}
});

sendImmediately, defaults to true, sends a basic authentication header. After setting it to false, it will retry when receiving a 401 (the server's 401 response must include the WWW-Authenticate specified authentication method).

Digest authentication is supported when sendImmediately is true.

OAuth login:

// Twitter OAuth
var qs = require('querystring')
 , oauth =
 { callback: 'http://mysite.com/callback/'
 , consumer_key: CONSUMER_KEY
 , consumer_secret: CONSUMER_SECRET
}
 , url = 'https://api.twitter.com/oauth/request_token'
;
request.post({url:url, oauth:oauth}, function (e, r, body) {
 // Ideally, you would take the body in the response
 // and construct a URL that a user clicks on (like a sign in button).
 // The verifier is only available in the response after a user has
 // verified with twitter that they are authorizing your app.
 var access_token = qs.parse(body)
 , oauth =
 { consumer_key: CONSUMER_KEY
 , consumer_secret: CONSUMER_SECRET
 , token: access_token.oauth_token
 , verifier: access_token.oauth_verifier
}
 , url = 'https://api.twitter.com/oauth/access_token'
;
 request.post({url:url, oauth:oauth}, function (e, r, body) {
 var perm_token = qs.parse(body)
 , oauth =
 { consumer_key: CONSUMER_KEY
 , consumer_secret: CONSUMER_SECRET
 , token: perm_token.oauth_token
 , token_secret: perm_token.oauth_token_secret
}
 , url = 'https://api.twitter.com/1/users/show.json?'
 , params =
 { screen_name: perm_token.screen_name
 , user_id: perm_token.user_id
}
;
 url += qs.stringify(params)
 request.get({url:url, oauth:oauth, json:true}, function (e, r, user) {
console.log(user)
})
})
})

Customized HTTP header

User-Agent and the like can be found in set in the options object. In the following example, we call the github API to find out the collection number and derivative number of a certain warehouse. We use a customized User-Agent and https.

var request = require('request');

var options = {
 url: 'https://api.github.com/repos/mikeal/request',
 headers: {
 'User-Agent': 'request'
}
};

function callback(error, response, body) {
 if (!error && response.statusCode == 200) {
 var info = JSON.parse(body);
 console.log(info.stargazers_count +"Stars");
 console.log(info.forks_count +"Forks");
}
}

request(options, callback);

cookies:

By default, cookies are Disabled. Set jar to true in defaults or options so that subsequent requests will use cookies.

var request = request.defaults({jar: true})
request('http://www.google.com', function () {
request('http://images.google.com')
})

By creating a new instance of request.jar(), you can use Customize cookies instead of requesting the global cookie jar.

var j = request.jar()
var request = request.defaults({jar:j})
request('http://www.google.com', function () {
request('http://images.google.com')
})

or

var j = request.jar()
var cookie = request.cookie('your_cookie_here')
j.setCookie(cookie, uri, function (err, cookie){})
request({url: 'http://www.google.com', jar: j}, function () {
request('http://images.google.com')
})

Note that setCookie requires at least three parameters, the last one Is the callback function.

You can use the pipe method of request to easily obtain the file stream of the image

 var request = require('request'),
 fs = require('fs');
 
 request('https://www.google.com.hk/images/srpr/logo3w.png').pipe(fs.createWriteStream('doodle.png'));

For more usage methods and instructions, click here to continue reading ：https://github.com/mikeal/request/

Example

A very simple example is written here to grab hotels from Qunar.com Query data (get the price ranking of each room type in the hotel within a certain period of time):

 var request = require('request'),
 fs = require('fs');
 
 
 var reqUrl = 'http://hotel.qunar.com/price/detail.jsp?fromDate=2012-08-18&toDate=2012-08-19&cityurl=shanghai_city&HotelSEQ=shanghai_city_2856&cn=5';
 
 request({uri:reqUrl}, function(err, response, body) {
 
 //console.log(response.statusCode);
 //console.log(response);
 
 //如果数据量比较大，就需要对返回的数据根据日期、酒店ID进行存储，如果获取数据进行对比的时候直接读文件
 var filePath = __dirname + '/data/data.js';
 
 if (fs.exists(filePath)) {
  fs.unlinkSync(filePath);
 
  console.log('Del file ' + filePath);
 }
 
 fs.writeFile(filePath, body, 'utf8', function(err) {
  if (err) {
  throw err;
  }
 
  console.log('Save ' + filePath + ' ok~');
 });
 
 console.log('Fetch ' + reqUrl + ' ok~');
 });

This example comes from a friend who is in the hotel business and wants to know what he provides to customers on the website Price competitiveness:

1. If the price offered is too low, you will make less money, so if your price is the lowest, you need to see what the second lowest is, and then decide Whether to adjust;

2. If the price provided is too high, the ranking results will be relatively low. There will be no customers to book the hotel, and the business will be gone.

Because the hotel is made There are many booking businesses, for example, more than 2,000. If you rely on manual checking of rankings one by one, it will be passive, and it will be difficult to expand. Therefore, I analyzed his needs and it is feasible and can be made into a good one. Real-time warning system (of course the data will be automatically refreshed on the page every 5 to 10 minutes). Only in this way can profits be maximized, the work efficiency of the sales and customer departments be improved, and the number of hotel cooperations and the company's personnel expansion be accelerated:

1. Do not lose money and do not do loss-making transactions;

2. If you find that the price provided is too low or too high, you need to support calling the API interface of the platform to directly modify the price;

3. There is a function to automatically generate analysis reports to analyze competitors' price adjustment strategies. Changes;

The above is the entire content of this article. I hope it will be helpful to everyone's study. For more related content, please pay attention to the PHP Chinese website!

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