ValueError when using json module in discord.py

Question 1

My intention is to set a channel for welcome messages immediately when the bot joins and to be able to change it using the command assigned. This is my code:

import discord
from discord.ext import commands
import json

def get_welcomechannel(client, message,):
    with open('welcomechannel.json', 'r') as f:
        welcomechannel = json.load(f)
    
    return welcomechannel[str(message.guild.id)]
@client.event
async def on_guild_join(guild):
    general = find(lambda x: x.name == 'general',  guild.text_channels)
    if general and general.permissions_for(guild.me).send_messages:
        await general.send(f'Hello {guild.name}! My name is {client.user.name} and my prefix is ``?``! run ``?help`` to begin using me!')

    with open('prefixes.json', 'r') as f:
        prefixes = json.load(f)   
    prefixes[str(guild.id)] = "?"

    with open ('prefixes.json', 'w') as f:
        json.dump(prefixes, f, indent=4)

    with open('welcomechannel.json', 'r') as f:
        welcomechannel = json.load(f)   
    welcomechannel[str(guild.id)] = "general"

    with open ('prefixes.json', 'w') as f:
        json.dump(prefixes, f, indent=4)
@client.event
async def on_guild_remove(guild):
    with open('prefixes.json', 'r') as f:
        prefixes = json.load(f)   
    prefixes.pop(str(guild.id))

    with open ('prefixes.json', 'w') as f:
        json.dump(prefixes, f, indent=4)

    with open('welcomechannel.json', 'r') as f:
        welcomechannel = json.load(f)   
    welcomechannel.pop(str(guild.id))

    with open ('welcomechannel.json', 'w') as f:
        json.dump(welcomechannel, f, indent=4)
        print(f"{guild.name} kicked me!")


#rest of code here...

@client.command(name="changewelcomechannel")
async def changewelcomechannel(ctx, welcomechannel):
    with open('welcomechannel.json', 'r') as f:
        welcomechannel = json.load(f)   
    
    welcomechannel[str(ctx.guild.id)] = welcomechannel

    with open ('welcomechannel.json', 'w') as f:
        json.dump(welcomechannel, f, indent=4)
        await ctx.send(f"Welcome channel is now **{welcomechannel}**!"

but I get this error:

 Ignoring exception in command changewelcomechannel:
2021-11-24T09:38:41.247854+00:00 app[worker.1]: Traceback (most recent call last):
2021-11-24T09:38:41.247927+00:00 app[worker.1]:   File "/app/.heroku/python/lib/python3.9/site-packages/discord/ext/commands/core.py", line 85, in wrapped
2021-11-24T09:38:41.247928+00:00 app[worker.1]:     ret = await coro(*args, **kwargs)
2021-11-24T09:38:41.247943+00:00 app[worker.1]:   File "/app/bot.py", line 352, in changewelcomechannel
2021-11-24T09:38:41.247943+00:00 app[worker.1]:     json.dump(welcomechannel, f, indent=4)
2021-11-24T09:38:41.247957+00:00 app[worker.1]:   File "/app/.heroku/python/lib/python3.9/json/__init__.py", line 179, in dump
2021-11-24T09:38:41.247958+00:00 app[worker.1]:     for chunk in iterable:
2021-11-24T09:38:41.247976+00:00 app[worker.1]:   File "/app/.heroku/python/lib/python3.9/json/encoder.py", line 431, in _iterencode
2021-11-24T09:38:41.247976+00:00 app[worker.1]:     yield from _iterencode_dict(o, _current_indent_level)
2021-11-24T09:38:41.248004+00:00 app[worker.1]:   File "/app/.heroku/python/lib/python3.9/json/encoder.py", line 405, in _iterencode_dict
2021-11-24T09:38:41.248005+00:00 app[worker.1]:     yield from chunks
2021-11-24T09:38:41.248018+00:00 app[worker.1]:   File "/app/.heroku/python/lib/python3.9/json/encoder.py", line 340, in _iterencode_dict
2021-11-24T09:38:41.248019+00:00 app[worker.1]:     raise ValueError("Circular reference detected")
2021-11-24T09:38:41.248041+00:00 app[worker.1]: ValueError: Circular reference detected

I did not have the full error code locally so I had copy and paste the heroku error code I could find.

I used the same structure in another command and it worked nicely. I am not so experienced with using the json module in python, so if someone could help, it would be awesome. Thanks a lot

edit: I finally realised what I did wrong, I was supposed to use another variable in

welcomechannel[str(ctx.guild.id)] = welcomechannel# this is supposed to be the new variable#

Question 2

The error is mentioning a circular reference, which is where you try to reference the object that you are inside of. You do this when you write:

welcomechannel[str(ctx.guild.id)] = welcomechannel

As you can see, you are assigning a property of the object welcomechannel to itself.

Mabey you want to try renaming the function parameter welcomechannel as it's currently ambiguous i.e a few lines after the function begins you overwrite it with a json object. You could also rename the variable here:

welcomechannel = json.load(f)

ttrss · Answer 1 · 2021-11-25T10:43:15

The error is mentioning a circular reference, which is where you try to reference the object that you are inside of. You do this when you write:

welcomechannel[str(ctx.guild.id)] = welcomechannel

As you can see, you are assigning a property of the object welcomechannel to itself.

Mabey you want to try renaming the function parameter welcomechannel as it's currently ambiguous i.e a few lines after the function begins you overwrite it with a json object. You could also rename the variable here:

welcomechannel = json.load(f)

but what do I do to rectify the error while still extracting the info?
I also used the same structure with another command and it worked. Is it alright if you explain the differences? This is the command client.command(name="changeprefix") async def changeprefix(ctx, prefix): with open('prefixes.json', 'r') as f: prefixes = json.load(f) prefixes[str(ctx.guild.id)] = prefix with open ('prefixes.json', 'w') as f: json.dump(prefixes, f, indent=4) await ctx.send(f"prefix is now {prefix}!")
The difference is that in this new example, you are using the function parameter 'prefix', and assigning it to a property of the json object 'prefixes'. I'll update my answer.
Ah, thank you, but it came up with another error. This time, a TypeError. I have updated my question to show the error.

ValueError when using json module in discord.py

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