Python：AttributeError：'NoneType'对象没有属性'append'

Question

My program looks like

# global
item_to_bucket_list_map = {}

def fill_item_bucket_map(items, buckets):
    global item_to_bucket_list_map

    for i in range(1, items + 1):
        j = 1
        while i * j <= buckets:
            if j == 1:
                item_to_bucket_list_map[i] = [j]
            else:
                item_to_bucket_list_map[i] = (item_to_bucket_list_map.get(i)).append(j)
            j += 1
        print "Item=%s, bucket=%s" % (i, item_to_bucket_list_map.get(i))


if __name__ == "__main__":
    buckets = 100
    items = 100
    fill_item_bucket_map(items, buckets)

When I run this, it throws me

AttributeError: 'NoneType' object has no attribute 'append'

Not sure why this would happen? When I am already creating a list at start of each j

Answer 1

Actually you stored None here: append() changes the list in place and returns None

 item_to_bucket_list_map[i] = (item_to_bucket_list_map.get(i)).append(j)

example:

In [42]: lis = [1,2,3]

In [43]: print lis.append(4)
None

In [44]: lis
Out[44]: [1, 2, 3, 4]

Answer 2

[...]
for i in range(1, items + 1):
    j = 1
    while i * j <= buckets:
        if j == 1:
            mylist = []
        else:
            mylist = item_to_bucket_list_map.get(i)
        mylist.append(j)
        item_to_bucket_list_map[i] = mylist
        j += 1
    print "Item=%s, bucket=%s" % (i, item_to_bucket_list_map.get(i))

The while loop, however, can be simplified to

    for j in range(1, buckets / i + 1): # + 1 due to the <=
        if j == 1:
            mylist = []
        else:
            mylist = item_to_bucket_list_map.get(i)
        mylist.append(j)
        item_to_bucket_list_map[i] = mylist

Answer 3

AttributeError always comes here: 'NoneType' object has no attribute 'categories' can someone help me?

import discord
from discord.ext import commands


from discord_slash import SlashCommand
from discord_slash.model import ButtonStyle
from discord_slash.utils.manage_components import (
    ComponentContext,
    create_actionrow,
    create_button,
)

client = commands.Bot(command_prefix="-", case_insensitive=True, help_command=None)

slash = SlashCommand(client)


TICKET_MOD_ROLE_ID = '915020370673799188'
MANAGEMENT_ROLE_ID = '915020370673799188'
GUILD_ID = '908012453227552848'

ticket_category = None
ticket_mod_role = None
management_role = None
guild = None


@client.event
async def on_ready():
    print("Bot is ready")

    global ticket_category, ticket_mod_role, management_role


    guild = client.get_guild(GUILD_ID)


    ticket_category = discord.utils.get(guild.categories, name="ticket")

    ticket_mod_role = guild.get_role(
        role_id=TICKET_MOD_ROLE_ID
    )
    management_role = guild.get_role(role_id=MANAGEMENT_ROLE_ID)


@client.event
async def on_component(ctx: ComponentContext):
    await ctx.defer(
        ignore=True
    )

    ticket_created_embed = discord.Embed(
        title="Ticket Processed",
        description=f"""Hey {ctx.author.name}! Thanks for opening a ticket with us today, but before we transfer you through to a manager, we have to approve your ticket. We have this step in place to prevent bots and spam tickets.
        Please describe your enquiry and our team will approve it shortly. We thank you in advance for your patience.""",
    )
[20:54]
overwrites = {
        guild.default_role: discord.PermissionOverwrite(view_channel=False),
        guild.me: discord.PermissionOverwrite(view_channel=True),
        ticket_mod_role: discord.PermissionOverwrite(view_channel=True),
    }

    ticket = await ticket_category.create_text_channel(
        f"{ctx.author.name}-{ctx.author.discriminator}", overwrites=overwrites
    )

    await ticket.send(
        ctx.author.mention, embed=ticket_created_embed
    )


@client.command()
@commands.has_role(TICKET_MOD_ROLE_ID)
async def sendticket(ctx):
    embed = discord.Embed(
        title="Contact Support",
        description="Click the button below to open a ticket",
    )

    actionrow = create_actionrow(
        *[
            create_button(
                label="Open Ticket", custom_id="ticket", style=ButtonStyle.primary
            ),
        ]
    )

    await ctx.send(embed=embed, components=[actionrow])


@client.command(aliases=["approve"])
@commands.has_role(TICKET_MOD_ROLE_ID)
async def up(ctx):
    overwrites = {
        ctx.guild.me: discord.PermissionOverwrite(view_channel=True),
        ctx.guild.default_role: discord.PermissionOverwrite(view_channel=False),
        ticket_mod_role: discord.PermissionOverwrite(view_channel=None),
        management_role: discord.PermissionOverwrite(view_channel=True),
    }
    await ctx.channel.edit(overwrites=overwrites)

    await ctx.channel.send(
        "Ticket Approved!\nYour ticket has been approved and has been transferred through to the Management Team. They will assist you further with your enquiry."
    )


@client.command()
@commands.has_role(TICKET_MOD_ROLE_ID)
async def close(ctx):
    await ctx.channel.delete()



client.run("........")