python3 urlencode and urldecode

The story background

When we search the content in the browser, we will find that the browser will automatically convert the content we enter into the content with quite a lot % The address of is as follows ：

https://www.baidu.com/s?wd=%E4%B8%BA%E4%BB%80%E4%B9%88&rsv_spt=1&rsv_iqid=0xeaa7d7410002e421&issp=1&f=8&rsv_bp=1&rsv_idx=2&ie=utf-8&tn=baiduhome_pg&rsv_enter=1&rsv_dl=tb&rsv_sug3=9&rsv_sug1=11&rsv_sug7=101&rsv_sug2=0&rsv_btype=i&prefixsug=%25E4%25B8%25BA%25E4%25BB%2580%25E4%25B9%2588&rsp=5&inputT=2965&rsv_sug4=3444

So why do browsers do this ？ What's the use of doing this ？

Cause analysis

Before we can understand the above problems, we need to find out URI、URL、 as well as URN

What is? URI、URL、URN

• URI(Uniform Resource Identifier： Uniform resource identifiers ): Use a compact string to represent abstract or physical resources .URI It only specifies how to arrange resources, but it does not specify how to obtain resources .

• URL(Uniform Resource Locator： Uniform resource locator )：URL yes URI The most common form of expression , It clearly explains how to get from a precise 、 Fixed location access to resources .URL It not only specifies how to identify resources, but also specifies how to obtain resources

  Most of the URL All follow a standard format that consists of three parts ：

  • URL The first part is called the scheme （scheme）, Describe the protocol type used to access the resource , This part is usually HTTP agreement （http://）
  • The second part gives the Internet address of the server eg: www.taobao.com
  • The rest specifies Web A resource on the server eg: /robots.txt

• URN(Uniform Resource Name： Unified resource name )：URN As a unique name for a specific content, it has nothing to do with the current location of the resource , Use these location independent URN You can move resources everywhere

• The relationship between the three is shown in the figure ：

  

Why does the browser want to escape our input

According to the above, we know that URL Is a resource qualifier , stay URL Some parameter strings in the use ke y=value The form of key value pairs is used to transfer parameters between key value pairs & symbols .

Suppose if your value contained = perhaps &, Then it will lead to receiving URL The server parsing error of resulted in the failure to obtain the correct resources , Therefore, it is necessary to bring about ambiguity & and = To escape a symbol is to encode it .

Or, URL The encoding format of is ASCII code , instead of unicode, That means you can't URL Include any non ASCII character , For example, Chinese , Otherwise, if the character sets supported by the client browser and the server browser are different, Chinese may cause problems .

There are many scenarios similar to the above situations, and there are no examples here , To avoid the above problems, the browser defaults to us URL Transference .

python urlencode and urldecode Use

stay python3 Chinese will be urlencode urldecode Coding needs to use urllib This library

• urlencode

import urllib
urllib.parse.quote(string, safe='/', encoding=None, errors=None)

• urldecode

import urllib
urllib.parse.unquote(string, encoding='utf-8', error='replace')

• Using examples

import urllib
urllib.parse.quote(' Workers ')
>>> '%E6%89%93%E5%B7%A5%E4%BA%BA'
urllib.parse.unquote('%E6%89%93%E5%B7%A5%E4%BA%BA')
>>> ' Workers '