How to use Python to prevent withdrawal of WeChat messages

WeChat is a social software launched by Tencent on January 21, 2011. Today I will show you how to use Python to prevent withdrawal of WeChat. Interested friends can learn about it.

1. Background introduction

The update and iteration of products will inevitably be accompanied by the launch and offline of functions. Today we are going to talk about a small new function launched by WeChat in 2014. : Withdraw message, users who use this function are refreshed and refreshed, but the users may scratch their heads and gnash their teeth to know what you have withdrawn. This is the so-called curiosity that killed the cat. (Curiosity kills the cat), today we will use Python to prevent WeChat message withdrawal to satisfy everyone’s curiosity! Related tutorials: Python video tutorial

2. Functional design

We hope that when a friend or someone in the group withdraws the message , the original message and sender information can be forwarded to the file assistant immediately (of course you can also send the message back to him, haha), so that we can view it more conveniently.

Let me demonstrate the implemented function for everyone.

3. Functional implementation

1. Implementation principle of WeChat message withdrawal

Let’s first understand the principle of WeChat message withdrawal:

In fact, the principle behind WeChat's message withdrawal is that when the operator clicks to withdraw, the client will automatically send a system message: "xxx has withdrawn a message", and then the other party's app will parse the message after receiving it and replace the original message. Just change the display style

Brother Zhu will show you the difference between the contents of normal message and withdraw message:
Normal Message: Content='You are so sexy', please pay attention MsgId='8784390488772995470'

Withdraw message: Content is a string of xml format Content

Let’s format it below and take a look

<sysmsg type="revokemsg">
  <revokemsg>
    <session>xxx</session>
    <oldmsgid>1090336364</oldmsgid>
    <msgid>8784390488772995470</msgid>
    <replacemsg><![CDATA["猪哥" 撤回了一条消息]]></replacemsg>
  </revokemsg>
</sysmsg>

Analyzing the Content field withdrawn above, we found that<msgid>8784390488772995470 The id of msgid></msgid> is consistent with the id of the message we sent before, and the label <replacemsg></replacemsg> also verified my guess, it is indeed replacing the original message with the new message.

2. Find the withdrawn message

According to the content of crawling normal message and withdraw message we found the rule: the withdrawal message will contain the previous msgid of the withdrawn message, then we only need to find the previous message, and the wxpy module caches the most recent 200 messages for us by default, so we only need Traverse these historical messages and compare msgid to find the withdrawn message!

If your WeChat messages are too frequent and the number of messages exceeds 200 within 2 minutes, you can set max_history larger.

3. Forwarding the withdrawn message

The principle is also understood, the withdrawn message has been found, and the last step is to forward the message. If you have played wxpy# before ##You must know it, you can forward the message with just one line of code:

msg.forward(bot.file_helper)

4. Code

Now that I have finished explaining the principle and process, I will post the code for everyone to see. The comments are quite detailed. , if you don’t understand something, you can ask me in the study group.

4. Function verification

##5. Summary

WeChat The message anti-withdrawal function is simple to implement, but very practical. The only shortcoming of the current project is the poor ease of use. Simply put, we have not deployed the project to the server. Every time we use it, we have to turn on the computer and run it, and it has to be turned on all the time. Pig Brother is considering deploying the project on a cloud server or packaging it into an apk later, which will be very convenient to use, and you can also send the apk to friends so that they can also experience this feature!

Learn this trick, and you no longer have to wonder what message the other party has withdrawn. Download the project and try it! After downloading the project, you can run it directly without modifying the code!

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