Python：检查键是否是字典的一部分

Question

I'm trying to make my own irc bot (for twitch) in Python. I have a dictionary with my commands:

commands = {

    '!ping': {
        'cooldown': 30,
        'return': '!pong'
    },

    '!random': {
        'cooldown': 30,
        'return': 'command',
        'argc': 2,
        'arg_username': True,
        'usage': '!random <min> <max>'
    }

} # End of commands

Then I have a function to check if the message that was send is indeed a command:

import string

def is_valid_command(command):
    return True if command in commands.keys() else False

So when i test this function out, it don't seems to work, and I don't know what I am doiing wrong:

message = "!ping"
print(str(is_valid_command(message)))
>>> False

I tried to change '!ping' inside the dictionary to "!ping", and virsa versa with the message, even deleted the '!' and it always says it's False.

Thanks in regards, Laurens

EDIT:

def is_valid_command(command):
    for key in commands.keys():
        print(key)
    print("input " + str(command))
    print(command in commands.keys())
    return command in commands.keys()

This result in this:

!ping
!random
input !ping
False

EDIT2: @e4c5 wanted me to use try/except, as i quickly try it (inside that methode), it still return False

try:
    cmd = commands[command]
    print ('Try True')
    return True
except KeyError:
    print('Try False')
    return False

EDIT3: u'!ping' before fixed this (message = u'!ping'), but when I read a string from somewhere else, is there a function that does this unicoding?

Answer 1

Your is_valid_command function can be simplified to:

def is_valid_command(command):
    return command in commands

Answer 2

I just tested your script and it seems to work fine.

Did some simplifications, but basically have the same code as you.

commands = {
    '!ping': {
        'cooldown': 30,
        'return': '!pong'
    },
    '!random': {
        'cooldown': 30,
        'return': 'command',
        'argc': 2,
        'arg_username': True,
        'usage': '!random <min> <max>'
    }
}

def is_valid_command(command):
    return command in commands.keys()

print(is_valid_command("!ping"))

Which returns True . If I try command !pong it returns False .

Answer 3

This pre checking is not needed and unpythonic. Instead of all these ccomplications, just do

try:
   cmd = commands[message]
   # do whatever with cmd
except KeyError:
   print ('Sorry not a valid command')

EAFP

Easier to ask for forgiveness than permission. This common Python coding style assumes the existence of valid keys or attributes and catches exceptions if the assumption proves false. This clean and fast style is characterized by the presence of many try and except statements. The technique contrasts with the LBYL style common to many other languages such as C.

Answer 4

Why are you not returning just:

return command in commands.keys()

That should be True/False already! hope this clarify!

As mentioned above to create a unicode string out of your messages just:

u'%s' % message

Answer 5

I am using python2.7 and your code returns True for me.

Instead of writing function, you can directly use :

message = "!ping" print(commands.has_key(message))

Answer 6

Yes, there is a function to convert a string to unicode. Use unicode function eg unicode('my_string') .

For example if your message from irc is stored in a variable message_from_irc then you can convert it as unicode(message_from_irc) .

I suggest you switch keyboard language to English when coding, in order to avoid this types of unexpected behaviors of code.