如何修复 python 中的“TypeError：'NoneType' 类型的参数不可迭代”

Question

I am building the VUI for a virtual assistant as a hobby project using pyttsx3 and SpeechRecognition. i first made a function called take_order() then in the next function run_agos() i checked if take_Order() contains some keyword to start an other process, see this code:

import speech_recognition as sr
import pywhatkit
import datetime
import winsound
import wikipedia
import pyjokes
import pyttsx3

listener = sr.Recognizer()
engine = pyttsx3.init()

def talk(text):
    engine.say(text)
    engine.runAndWait()


def take_order():
    try:
        with sr.Microphone() as source:
            print('listening...')
            voice = listener.listen(source)
            command = listener.recognize_google(voice)
            command = command.lower()
            if 'alex' in command:
                command = command.replace('alexa', '')
                print(command)
            else:
                return
            return command
    except pass



def run_agos():
    task = take_order()

    if 'play' in task:
        song = task.replace('play', '')
        talk('playing ' + song)
        pywhatkit.playonyt(song)
    elif 'time' in task:
        time = datetime.datetime.now().strftime('%I:%M %p')
        print(time)
        talk('Current time is ' + time)
    elif 'who is' in task:
        person = task.replace('who is', '')
        try:
            info = wikipedia.summary(person, 1)
            print(info)
            talk(info)
        except wikipedia.exceptions.DisambiguationError as e:
            print(e.options)
            talk(person + 'may refer to')
            talk(e.options)
    elif 'what is' in task:
        thing = task.replace('what is', '')
        try:
            info = wikipedia.summary(thing, 1)
            print(info)
            talk(info)
        except wikipedia.exceptions.DisambiguationError as e:
            print(e.options)
            talk(thing + 'may refer to')
            talk(e.options)
    elif 'joke' in task:
        joke = pyjokes.get_joke()
        talk(joke)
        print(joke)
    else:
        talk('I did not hear that, pleas repeat the command.')
    return run_agos()


while True:
    run_agos()

At first it works fine, however after a while I get TypeError: argument of type 'NoneType' is not iterable and the program shuts down. I also get the extit code: -1073741819 (0xC0000005).How can I fix this error so it will keep running the program?

Answer 1

It looks like in the take_order function, you are either returning nothing when an error occurs or returning nothing as well when 'alexa' isn't in the command. Then your code checks if 'play' in task . Here, task is None since nothing was returned. This is your main issue. I would suggest returning a specific string or a value for example -1. Then, right after task = take_order() , check if task is that value. for example

def take_order():
    try:
        with sr.Microphone() as source:
            print('listening...')
            voice = listener.listen(source)
            command = listener.recognize_google(voice)
            command = command.lower()
            if 'alex' in command:
                command = command.replace('alexa', '')
                print(command)
            else:
                return -1
            return command
    except: return -1

def run_agos():
    task = take_order()
    if task == -1: return
    ...

One more thing: You always do return run_agos() at the end of run_agos() which recursively calls itself. This is bad practice since you already have a while True loop that calls the function forever. I would suggest removing the return statement in the end of run_agos