收集所有关键错误

Question

我想创建一个类来存储在init中发生的关键错误的列表。

class Basic:
    missing_view_data_columns = []

    def __init__(self, some_dict):
        self.some_dict = some_dict
        try:
            self.basic_1 = self.some_dict['basic_1']
            self.basic_2 = self.some_dict['basic_2']

        except KeyError as e:
            self.add_missing_data_column(e)

    @classmethod
    def add_missing_data_column(cls, column_name):
        cls.missing_view_data_columns.append(column_name)


class Specific(Basic):

    def __init__(self, some_dict):
        super().__init__(some_dict)
        try:
            self.specific_1 = self.some_dict['specific_1']
            self.specific_2 = self.some_dict['specific_2']

        except KeyError as e:
            self.add_missing_data_column(e)


rem = Specific({})

print(f"missing_keys: {rem.missing_view_data_columns}")

这是我的方法，但是不起作用。以下代码将仅打印出现的第一个关键错误。我也可以说它看起来不太好，因为我需要两次编写相同的异常。

您能给我建议如何创建此功能吗？

Answer 1

您可以实现自己的字典：

from collections.abc import Mapping

class MissingDict(Mapping):
    def __init__(self, d, cls):
      self._d = d
      self.cls = cls

    def __getitem__(self, i):
      if i in self._d:
          return self._d[i]

      self.cls.add_missing_data_column(i)

    def __iter__(self): return iter(self._d)
    def __len__(self):  return len(self._d.keys())

这将存储字典实例并在您尝试访问新键时更新您班级的缺失列表。像这样使用：

class Basic:
    missing_view_data_columns = []

    def __init__(self, some_dict):
        self.some_dict = MissingDict(some_dict, self)
        self.basic_1 = self.some_dict['basic_1']
        self.basic_2 = self.some_dict['basic_2']

    @classmethod
    def add_missing_data_column(cls, column_name):
        cls.missing_view_data_columns.append(column_name)


class Specific(Basic):

    def __init__(self, some_dict):
        super().__init__(some_dict)
        self.specific_1 = self.some_dict['specific_1']
        self.specific_2 = self.some_dict['specific_2']


rem = Specific({})

print(f"missing_keys: {rem.missing_view_data_columns}")

显示：

missing_keys: ['basic_1', 'basic_2', 'specific_1', 'specific_2']

Answer 2

我已经修改了您的代码以遍历您要检查的每个键：

class Basic:
    missing_view_data_columns = []

    def __init__(self, some_dict):
        self.some_dict = some_dict
        keys = ['basic_1', 'basic_2']
        for key in keys:
            self.check_for_key_error(key)

    def check_for_key_error(self, key):
        try:
            self.key = self.some_dict[key]
        except KeyError as e:
            self.add_missing_data_column(e)

    @classmethod
    def add_missing_data_column(cls, column_name):
        cls.missing_view_data_columns.append(column_name)


class Specific(Basic):

    def __init__(self, some_dict):
        super().__init__(some_dict)
        keys = ['basic_1', 'basic_2']
        for key in keys:
            self.check_for_key_error(key)


rem = Specific({})

print(f"missing_keys: {rem.missing_view_data_columns}")

输出：

missing_keys: [KeyError('basic_1'), KeyError('basic_2'), KeyError('basic_1'), KeyError('basic_2')]

Answer 3

您确定您确实要存储异常消息吗？因为看起来您只想知道字典中缺少哪些键。在这种情况下，您应该只使用dictionary.get()方法，如果不存在密钥，则该方法将返回None。如果失败，还可以设置默认返回值，例如dictionary.get(something, "return this if not found")。找不到的密钥列表可以像这样完成：

keys_to_look_for = ["key_1", "key_2", "key_n"]
return [k for k in keys_to_look_for if not some_dict.get(k)]

Answer 4

您可以在不使用try/except块的情况下解决问题：这是执行此操作的代码，

class Basic:
    missing_view_data_columns = []

    def __init__(self, some_dict):
        self.some_dict = some_dict

        self.basic_1 = self.some_dict.get('basic_1') or self.add_missing_data_column(KeyError('basic_1'))
        self.basic_2 = self.some_dict.get('basic_1') or self.add_missing_data_column(KeyError('basic_2'))

    @classmethod
    def add_missing_data_column(cls, column_name):
        cls.missing_view_data_columns.append(column_name)


class Specific(Basic):
    def __init__(self, some_dict):
        super().__init__(some_dict)

        self.specific_1 = self.some_dict.get('specific_1') or self.add_missing_data_column(KeyError('specific_1'))
        self.specific_2 = self.some_dict.get('specific_2') or self.add_missing_data_column(KeyError('specific_2'))


rem = Specific({ "specific_1": 1})

print(f"missing_keys: {rem.missing_view_data_columns}")

希望这会有所帮助！