如何在python3中修复'NoneType'的属性错误？

Question

我正在尝试创建一个将通过使用类将两个字典合并的函数，但由于无法保持AttributeError'NoneType'而无法实现。但是，当单独运行代码而没有整个代码时，该函数工作，这使我感到困惑。 我的整个代码是：

prices = {
    "apple": 1,
    "beets": 1,
    "carrots": 1}

cookbook={}

total=20


def handle_commands():
    keep_going=True
    while keep_going:
        choices=input("$ ").strip().lower().split()
        command=choices[0]
        if command == "loadrecipefile":
            recipe_file=choices[1]
            loadrecipefile(recipe_file)
        elif command == "printrecipes":
            printrecipes()
        elif command == "printiinventory":
            printiinventory()
        elif command == "printmoney":
            printmoney()
        elif command == "preparedish":
            recipe_name=choices[1]
            preparedish(recipe_name)
        elif command == "buyingredient":
            name=choices[1]
            number=int(choices[2])
            buyingredient(name, number)
        elif command == "setprices":
            apple_price=int(choices[1])
            beets_price=int(choices[2])
            carrots_price=int(choices[3])
            setprices(apple_price, beets_price, carrots_price)
        elif command == "mergerecipes":
            r1=choices[1]
            r2=choices[2]
            mergerecipes(r1,r2)
        elif command == "quit":
            keep_going=False
            break
        else:
            print("Sorry that is not an acceptable command")
    return 

def loadrecipefile (recipe_file):
    infile=open(recipe_file)
    Linelist=infile.readlines()
    for line in Linelist:
        wordList=line.split()
        r1=Recipe(wordList[0],int(wordList[1]),int(wordList[2]),int(wordList[3]))
        cookbook.addRecipe(r1)

def printrecipes():
    for recipe in cookbook.allRecipes():
        print(recipe.getName(),int(recipe.getApples()),int(recipe.getBeets()),int(recipe.getCarrots()))

def buyingredient(name, number:int):
    global total
    if number*prices[name] > total:
        print("Not enough cash!")
    if iinventory == 'apple':
        iinventory.getApples()
    elif iinventory == 'beets':
        iinventory.getBeets()
    elif iinventory == 'carrots':
        iinventory.getCarrots()

    iinventory[name] += number
    total -= number*prices[name]

def printiinventory():
    print(int(iinventory.getApples()), int(iinventory.getBeets()), int(iinventory.getCarrots()))

def printmoney():
    print(total)

def CanPrepareDish(recipe_name):
    recipe = cookbook[recipe_name]
    for ingred in recipe:
        if ingred not in iinventory:
            return False
        if iinventory[ingred] < recipe[ingred]:
            return False
    return True

def preparedish(recipe_name):
    if not CanPrepareDish(recipe_name):
        print("Not enough ingredients")
    else:
        recipe = cookbook[recipe_name]
        for ingred in recipe:
            iinventory[ingred] -= recipe[ingred]
        if recipe_name in iinventory:
            iinventory[recipe_name] +=1
        else:
            iinventory[recipe_name] = 1
            print("Dish prepared")

    #for recipe in cookbook.allRecipes():
        #if recipe_name == recipe.getName():


def setprices(apple_price, beets_price, carrots_price):
    for name,value in prices.items():
        prices["apple"] = apple_price
        prices["beets"] = beets_price
        prices["carrots"] = carrots_price

def mergerecipes(r1,r2):
    dish1 = cookbook.getRecipe(r1)
    dish2 = cookbook.getRecipe(r2)
    name = dish1.getName() + dish2.getName()
    apple_num = dish1.getApples() + dish2.getApples()
    beet_num = dish1.getBeets() + dish2.getBeets()
    carrot_num = dish1.getCarrots() + dish2.getCarrots()
    rnew=Recipe(name,apple_num,beet_num,carrot_num)

class Recipe:
    def __init__(self,name,apple_num,beet_num,carrot_num):
        self.name=str(name)
        self.apple_num=int(apple_num)
        self.beet_num=int(beet_num)
        self.carrot_num=int(carrot_num)
    def getName(self):
        return self.name
    def getApples(self):
        return self.apple_num
    def getBeets(self):
        return self.beet_num
    def getCarrots(self):
        return self.carrot_num

class Iinventory:
    def __init__(self):
        self.apple_num=0
        self.beets_num=0
        self.carrots_num=0
    def getApples(self):
        return int(self.apple_num)
    def getBeets(self):
        return int(self.beets_num)
    def getCarrots(self):
        return int(self.carrots_num)

iinventory=Iinventory()

class Cookbook:
    def __init__(self):
        self.Cooklist=[]
    def addRecipe(self,Recipe):
        self.Cooklist.append(Recipe)
    def getRecipe(self,recipe_name):
        for recipe in self.Cooklist:
            if recipe_name == recipe.getName():
                return recipe
    def allRecipes(self):
        for Recipe in self.Cooklist:
            return self.Cooklist

cookbook=Cookbook()

handle_commands()

但是只有这部分代码，功能mergerecipes才起作用。我想知道为什么以及如何解决为该函数在我的整个代码中工作而修复代码的错误。

我的整个代码段：

cookbook={}
class Recipe:
    def __init__(self,name,apple_num,beet_num,carrot_num):
        self.name=str(name)
        self.apple_num=int(apple_num)
        self.beet_num=int(beet_num)
        self.carrot_num=int(carrot_num)
    def getName(self):
        return self.name
    def getApples(self):
        return self.apple_num
    def getBeets(self):
        return self.beet_num
    def getCarrots(self):
        return self.carrot_num

class Cookbook:
    def __init__(self):
        self.Cooklist=[]
    def addRecipe(self,Recipe):
        self.Cooklist.append(Recipe)
    def getRecipe(self,recipe_name):
        for recipe in self.Cooklist:
            if recipe_name==recipe.getName():
                return recipe
    def allRecipes(self):
        for Recipe in self.Cooklist:
            return self.Cooklist

cookbook=Cookbook()

def mergerecipes(r1,r2):
    dish1 = cookbook.getRecipe(r1)
    dish2 = cookbook.getRecipe(r2)
    name = dish1.getName() + dish2.getName()
    apple_num = dish1.getApples() + dish2.getApples()
    beet_num = dish1.getBeets() + dish2.getBeets()
    carrot_num = dish1.getCarrots() + dish2.getCarrots()
    rnew=Recipe(name,apple_num,beet_num,carrot_num)
    cookbook.addRecipe(rnew)
    print(rnew.getName(),int(rnew.getApples()),int(rnew.getBeets()),int(rnew.getCarrots()))

def loadrecipefile (recipe_file):
    infile=open(recipe_file)
    Linelist=infile.readlines()
    for line in Linelist:
        wordList=line.split()
        r1=Recipe(wordList[0],int(wordList[1]),int(wordList[2]),int(wordList[3]))
        cookbook.addRecipe(r1)

def printrecipes():
    for recipe in cookbook.allRecipes():
        print(recipe.getName(),int(recipe.getApples()),int(recipe.getBeets()),int(recipe.getCarrots()))

因此，当我加载文本文件时，它将“食谱”输入到食谱中，然后您便可以通过打印食谱查看。

输出示例为：

loadrecipefile('recipes.txt')        
printrecipes() 
Dish1 2 4 1
Dish2 2 2 2
Dish3 1 2 4
Dish4 0 2 1
mergerecipes('Dish1','Dish3')
printrecipes() 
Dish1 2 4 1
Dish2 2 2 2
Dish3 1 2 4
Dish4 0 2 1
Dish1Dish3 3 6 5

**如果混淆：我在运行整个代码时尝试运行合并配方，但出现此错误：

$ loadrecipefile recipes.txt
$ printrecipes
Dish1 2 4 1
Dish2 2 2 2
Dish3 1 2 4
Dish4 0 2 1
$ mergerecipes Dish1 Dish2
name = dish1.getName() + dish2.getName()
AttributeError: 'NoneType' object has no attribute 'getName'

所有帮助将不胜感激

Answer 1

您在输入上调用lower()，因此'Dish1'变成'dish1'，在配方列表中找不到，因此getRecipe()返回{{1 }}。