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Three methods of realizing network request in pyodide

2022-07-19 13:08:00 【InfoQ】

original text ：

https://lwebapp.com/zh/post/pyodide-fetch

demand

Xiaobian mentioned one before

On-line Python Tools

, The core technology uses a technology called

Pyodide

The library of , To be able to make Python Run on Web page , But Xiaobian found in the process of learning , Not all Python The built-in library or extension library can run , such as

requests

Is not supported .

According to this

issue

Discussion under ,

requests

Depend on

Lib/http.client.py

, The latter depends on

Lib/sockets.py

, The latter depends on the need

<sys/socket.h>

socketmodule.c

. Emscripten Provide

<sys/socket.h>

Support , But if we use it , that http Requests are only made when we accept them WebSocket It will work only when it is used together with the custom server （ Or proxy all requests through such a server that can forward requests ） As the real http request , This design is not ideal .

So if your local Python The program uses

requests

Methods , Switch to our online Python When the tool is running , Need to update the usage of network request . Here we briefly introduce 3 A method of network request .

Method

1. http.open_url

Synchronously get the given URL Request data

import pyodide
print(pyodide.http.open_url('https://mocki.io/v1/d4867d8b-b5d5-4a48-a4ab-79131b5809b8').read())

On-line Demo:

Python Playground - http.open_url

2. http.pyfetch

obtain url And return the response

import pyodide

async def get_data():
 response = await pyodide.http.pyfetch('https://mocki.io/v1/d4867d8b-b5d5-4a48-a4ab-79131b5809b8')
 data = await response.json()
 print(data)

get_data()

On-line Demo:

Python Playground - http.pyfetch

This method is recommended for obtaining image data

#  Ask for pictures 
response = await pyodide.http.pyfetch('https://gcore.jsdelivr.net/gh/openHacking/[email protected]/img/16576149784751657614977527.png')
#  Return the response body as a byte object 
image_data = await response.bytes()

Detailed reference cases ：

Web version Python Picture to character

3. js Module fetch

Pyodide Packaged js API, Use native js Of fetch API You can realize the network request

import json
from js import fetch,JSON

async def get_data():
 response = await fetch('https://mocki.io/v1/d4867d8b-b5d5-4a48-a4ab-79131b5809b8',{'method':'GET'})
 data = await response.json()
 print(JSON.stringify(data))

await get_data()

On-line Demo:

Python Playground - js fetch

summary

The above is what I summarized in Pyodide Commonly used 3 A network request method , There may be a lot of deficiencies , If you have a better way, welcome to share .