python - 不返回 YAML 文件的更新并在字符串更新时返回 TypeError

Question

我有代码应该抓取 YAML 文件并将其读入(成功)，但也应该能够更新 YAML 返回三个选项之一:

• 成功更新消息，其中包含对文件的所有更改。
• 更新失败消息，其中可能包含文件未正确更新的位置。
• 让用户知道他/她没有传递对文件进行的任何更改(YAML 文件中的冗余条目)。

第二个和第三个选项效果很好，但每当我更新时，第一个选项都会返回 TypeError:字符串索引必须是整数 或 TypeError:'int' object is not iterable我的字典 d 中嵌套字典之外的任何值。

这是我想出的代码:

class YAML_Config:
    '''
    Class used to interact with .YAML filetypes. Allows the creation of objects \
    that can be manipulated and save certain YAML files and configuration settings.
    '''

    def __init__(self, filename):
        '''
        Initial defintion. Defines the location for saving a new .YAML file or for loading \
        a previous one. The dictionary corresponding to the .YAML file is saved to self.dict. \
        If this is a new .YAML file, an empty dictionary is created.

        Input Arguments:
            -filename: (string) The name of the file where the current .YAML file is \
            located or the new .YAML will be saved.
        '''
        #Get the filename and save it to the class as a property.
        self.file = filename

        #Check if the file exists...
        if os.path.isfile(self.file):

            #Prepare to open the file with reading capabilities
            with open(self.file,'r') as infile:

                #Get a dictionary with all of the YAML informatin.
                yaml_dict = yaml.load(infile)

        #If the file does not exist...
        else:

            #Create an empty dictionary to save all YAML data.
            yaml_dict = {}

            #Create an empty .yaml file with the dictionary.
            with open(self.file, 'w') as infile:

                #Save updated dictionary to YAML file.
                yaml.dump(yaml_dict, infile, default_flow_style=False)

            print('YAML configuration file not found. New, empty dictionary, and .yaml file created.')

        self.dict=yaml_dict




    def update_value(self, kwargs):
        '''
        Used to update YAML files, and checks that the files were updated properly.
        '''
        #If these are not keyword arguments, then throw an error.
        assert kwargs, 'Input Error'

        #Get the YAML dictionary before it is updated.
        yaml_dict = self.dict


        #Make a copy of the dictionary to compare against later.
        yaml_dict_original = copy.deepcopy(self.dict)

        #Check if the dictionary is nonetype. This happens if the file is new as the file is empty.
        if yaml_dict_original is None:

            #Redefine orginal dictionary as an empty dictionary.
            yaml_dict_original={}

            #The new dictionary will simply be what is passed to the function.
            yaml_dict=kwargs

        else:

            #Update the original dictionary and update it with the arguments passed.
            #This also updates self.dict as yaml_dict is simply a reference to
            #that dictionary, not a copy of it.
            yaml_dict.update(kwargs)


        #Check if changes were made
        if (yaml_dict==yaml_dict_original) is False:

            #Open the YAML file to write to it.
            with open(self.file, 'w') as outfile:

                #Save updated dictionary to YAML file.
                yaml.dump(self.dict, outfile, default_flow_style=False)


    #Check that the file actually updated properly:

            #Double-check the file that it actually updated.
            with open(self.file, 'r') as infile:

                lastupdate = yaml.load(infile)

            #Get any nonmatching values between what should be in the YAML file and what actually is.
            errors = { k : yaml_dict[k] for k in set(yaml_dict) - set(lastupdate) }

            #Find out what changed in the YAML file.
            edits = { k : yaml_dict_original[k] for k in set(yaml_dict_original) - set(lastupdate) }

            #Check if errors is not empty. Evaluating dictionaries as boolean either returns True (not empty)
            #or False (empty).
            if bool(errors) is True:

                #First line of return print statement.
                print('The following entries did not update successfully:')

                #Loop through keys in errors
                for n in errors:

                    #Print the current key
                    print (n)

                    #Loop through entries of current key
                    for m in errors[n]:

                        #Print current entry of current key
                        print (m,':',errors[n][m])

            #Saved properly, check for edits and display to user.
            else:

                #Find where any edits were made.
                edits = {k: yaml_dict_original[k] for k in yaml_dict_original if k in lastupdate and yaml_dict_original[k] != lastupdate[k]}

                #Show user what edits were successfuly made.
                print('%s was successfully updated with the following changes:' %  os.path.basename(self.file))

                #Loop through keys in edits
                for n in edits:

                    #Print the current key
                    print (n)

                    #Loop through entries of current key
                    for m in edits[n]:

                        #Print current entry of current key
                        print (m,':',edits[n][m])

        #If no changes were made...        
        else:

            #Show user what edits were successfuly made.
            print('No changes to %s were passed. File not updated.' %  

    os.path.basename(self.file))



test=YAML_Config(r'...Path\Python Work\yaml_test.yaml')

d = {'A': 7, 'B':{'C':'D', 'D':False, 'E':'Julio'},\
     'The Real C': {'J?':'Yes, this is J.', 'K' : 241},'Q' : 'PQ'}

test.update_value(d)

第一个错误部分:

b = {'A': '', 'B':{'C':'D', 'D':False, 'E':'Julio'},\
         'The Real C': {'J?':'Yes, this is J.', 'K' : 241},'Q' : 'PQ'}

#TypeError: string indices must be integers.
test.update_value(b)

第二个错误部分:

f = {'A': 7, 'B':{'C':'D', 'D':False, 'E':'Julio'},\
         'The Real C': {'J?':'Yes, this is J.', 'K' : 241},'Q' : 2}

#TypeError: 'int' object is not iterable.
test.update_value(f)

每次运行此代码时，YAML 文件都会更新。所以实际的更新正在工作，但我不太确定为什么我找不到字典更新的索引。我对 Python 有点生疏，而且对 YAML 还很陌生，所以我可能会在这里遗漏一些明显的东西。

我使用的是 Python 3.6.5。

Answer 1

您的代码在这一行出错:

                    # Loop through entries of current key
                    for m in edits[n]:

此时 edits 是一个字典:{A: 7}(因为 A 是具有更改值的键)。您的代码似乎只预测复杂值的变化(例如 B 的变化)，因为如果您这样做:

b = {'A': 7, 'B':{'C':'D', 'D':True, 'E':'Julio'},\
        'The Real C': {'J?':'Yes, this is J.', 'K' : 241},'Q' : 'PQ'}

你得到:

test.yaml was successfully updated with the following changes:
B
C : D
D : False
E : Julio

因此，您应该重新考虑您的“报告”并将其更新为不仅可以处理 dict 值，还可以处理 list 和基元(YAML 标量)的值:字符串、整数、 bool 值等):

            # Show user what edits were successfuly made.
            print('{} was successfully updated with the following changes:'.format(os.path.basename(self.file)))
            # Loop through keys in edits
            for n in edits:
                # Loop through entries of current key
                if isinstance(edits[n], dict):
                    # Print the current key
                    print(n)
                    for m in edits[n]:
                        # Print current entry of current key
                        print(m, ':', edits[n][m])
                elif isinstance(edits[n], list):
                    # Print the current key followed by the elements
                    print(n)
                    for m in edits[n]:
                        # Print current entry of current key
                        print('- ', [m])
                else:  # scalar
                    print('{}: {}'.format(n, edits[n]))

然后你的输出将是:

test.yaml was successfully updated with the following changes:
A: 7
test.yaml was successfully updated with the following changes:
A: 
Q: PQ

(假设您相继运行两个额外更新)。