ClientSession does not encode dict params

[rmillet-rs]

Long story short

When passing params as a dict to make client queries, I expect them to be correctly encoded so the original value is retrieved by the server.

Expected behaviour

When passing a dict: params = { 'a': 'A%20B' } to a ClientSession, I expect the query to be formatted as ?a=A%2520B

Actual behaviour

Query looks like ?a=A+B

Steps to reproduce

import aiohttp
import asyncio

params = { 'a': 'A%20B' }
# Same with tuple:
# params = [ ('a', 'A%20B') ]

async def x():
    async with aiohttp.ClientSession() as session:
        async with session.get('http://127.0.0.1/', params=params) as resp:
            print(resp.url)
            print(await resp.text())

asyncio.get_event_loop().run_until_complete(x())

Output:

http://127.0.0.1/?a=A+B
A B

Expected output:

http://127.0.0.1/?a=A%2520B
A%20B

Server side PHP code:

<?php
echo $_GET['a'];

In doc it is written that dict params will be encoded but not str: https://docs.aiohttp.org/en/stable/client_quickstart.html#passing-parameters-in-urls

Your environment

aoihttp client 3.5.4
python 3.6.3

[asvetlov]

{ 'a': 'A%20B' } is correctly normalized into canonical form ?a=A+B.
If you want to disable normalization please use encoded=True as mentioned in the doc below: https://docs.aiohttp.org/en/stable/client_quickstart.html#passing-parameters-in-urls

[rmillet-rs]

Hello, if I read well, encoded=True is to use only when we have URL already built: Passing params overrides encoded=True, never use both options.

In my case, I want the client to build the URL and encode my parameters.
And aiohttp doc lets me think, it will do the encoding: You can see that the URL has been correctly encoded by printing the URL. (with a quite simple example with no "strange" character).

It is probably not clear enough but in my example: A%20B is not an URL encoded value, but the raw string I am manipulating. A more concrete example may be params = { 'a': 'Only today: save %20 on my awesome product!' }.

With requests which as a similar syntax, I got the expected behaviour:

from requests import Session

s = Session()
params = { 'a': 'A%20B' }

resp = s.get('http://127.0.0.1/', params=params)
print(resp.url)
print(resp.text)

Outputs:

http://127.0.0.1/?a=A%2520B
A%20B

If it is a limitation, it should at least be indicated in the doc.

It seems to be related to aio-libs/yarl#181

Cheers