Gufo HTTP Example: Get Request

Get is one of the basic HTTP operations allowing to download single page. We have mastered how to process synchronous get request in our get.py example. The asynchronous implementation is only slightly more complicated.

import asyncio
import sys

from gufo.http.async_client import HttpClient


async def main(url: str) -> None:
    async with HttpClient() as client:
        r = await client.get(url)
        if r.status != 200:
            print(f"Invalid response code: {r.status}")
            return
        print(r.content.decode())


asyncio.run(main(sys.argv[1]))

Let's see the details.

import asyncio
import sys

from gufo.http.async_client import HttpClient


async def main(url: str) -> None:
    async with HttpClient() as client:
        r = await client.get(url)
        if r.status != 200:
            print(f"Invalid response code: {r.status}")
            return
        print(r.content.decode())


asyncio.run(main(sys.argv[1]))

To run async function from our synchronous script, so we need to import asyncio to use asyncio.run().

import asyncio
import sys

from gufo.http.async_client import HttpClient


async def main(url: str) -> None:
    async with HttpClient() as client:
        r = await client.get(url)
        if r.status != 200:
            print(f"Invalid response code: {r.status}")
            return
        print(r.content.decode())


asyncio.run(main(sys.argv[1]))

Import sys module to parse the CLI argument.

Warning

We use sys.argv only for demonstration purposes. Use argsparse or alternatives in real-world applications.

import asyncio
import sys

from gufo.http.async_client import HttpClient


async def main(url: str) -> None:
    async with HttpClient() as client:
        r = await client.get(url)
        if r.status != 200:
            print(f"Invalid response code: {r.status}")
            return
        print(r.content.decode())


asyncio.run(main(sys.argv[1]))

HttpClient object holds all necessary API. We're using an asynchronous version from gufo.http.async_client.

import asyncio
import sys

from gufo.http.async_client import HttpClient


async def main(url: str) -> None:
    async with HttpClient() as client:
        r = await client.get(url)
        if r.status != 200:
            print(f"Invalid response code: {r.status}")
            return
        print(r.content.decode())


asyncio.run(main(sys.argv[1]))

We define our asychronous main function and expect resource URL.

import asyncio
import sys

from gufo.http.async_client import HttpClient


async def main(url: str) -> None:
    async with HttpClient() as client:
        r = await client.get(url)
        if r.status != 200:
            print(f"Invalid response code: {r.status}")
            return
        print(r.content.decode())


asyncio.run(main(sys.argv[1]))

First, we need to create HttpClient object which wraps the client's session. The HttpClient may be used as an instance directly or operated as asynchronous context manager using the async with clause. When used as a context manager, the client automatically closes all connections on the exit of context, so its lifetime is defined explicitly.

HttpClient constructor offers lots of configuration variables for fine-tuning. Refer to the HttpClient reference for further details. In our example we use default settings.

import asyncio
import sys

from gufo.http.async_client import HttpClient


async def main(url: str) -> None:
    async with HttpClient() as client:
        r = await client.get(url)
        if r.status != 200:
            print(f"Invalid response code: {r.status}")
            return
        print(r.content.decode())


asyncio.run(main(sys.argv[1]))

.get() method starts a HTTP GET request and await for response headers. It assepts an url as mandatary argument and returns a SyncResponse instance. The function is asyncronous and needs to be awaited.

import asyncio
import sys

from gufo.http.async_client import HttpClient


async def main(url: str) -> None:
    async with HttpClient() as client:
        r = await client.get(url)
        if r.status != 200:
            print(f"Invalid response code: {r.status}")
            return
        print(r.content.decode())


asyncio.run(main(sys.argv[1]))

We can inspect response code and headers without reading whole response body. For our example we just check the status code is 200 OK.

import asyncio
import sys

from gufo.http.async_client import HttpClient


async def main(url: str) -> None:
    async with HttpClient() as client:
        r = await client.get(url)
        if r.status != 200:
            print(f"Invalid response code: {r.status}")
            return
        print(r.content.decode())


asyncio.run(main(sys.argv[1]))

If status code is not OK, we print and error message and terminate our function.

import asyncio
import sys

from gufo.http.async_client import HttpClient


async def main(url: str) -> None:
    async with HttpClient() as client:
        r = await client.get(url)
        if r.status != 200:
            print(f"Invalid response code: {r.status}")
            return
        print(r.content.decode())


asyncio.run(main(sys.argv[1]))

The .content attribute of Response contains the response body. This attribute has type of bytes, so we convert it into str using .decode() method. In our example we consider the response is encoding using UTF-8 encoding. Then we print decoded result.

import asyncio
import sys

from gufo.http.async_client import HttpClient


async def main(url: str) -> None:
    async with HttpClient() as client:
        r = await client.get(url)
        if r.status != 200:
            print(f"Invalid response code: {r.status}")
            return
        print(r.content.decode())


asyncio.run(main(sys.argv[1]))

Lets run our main() function pass first command-line parameter as url.

Running

Let's check our script. Run example as:

$ python3 examples/async/get.py https://gufolabs.com/
<!DOCTYPE html>
<html>
...