在Django中的clean_data和cleaning_data.get之间的区别 [英] Difference between cleaned_data and cleaned_data.get in Django

问题描述

我已经看到一些示例代码，如：

I've seen some samples codes like:

    def clean_message(self):
    message = self.cleaned_data['message']
    num_words = len(message.split())
    if num_words < 4:
        raise forms.ValidationError("Not enough words!")
    return message

和一些例子：

def clean(self):
    username = self.cleaned_data.get('username')
    password = self.cleaned_data.get('password')
    ...
    self.check_for_test_cookie()
    return self.cleaned_data

两者有什么区别？

推荐答案

.get（） 基本上是将元素从字典。我通常使用 .get（），当我不确定字典中的条目是否会在那里。例如：

.get() is basically a shortcut for getting an element out of a dictionary. I usually use .get() when I'm not certain if the entry in the dictionary will be there. For example:

>>> cleaned_data = {'username': "bob", 'password': "secret"}
>>> cleaned_data['username']
'bob'
>>> cleaned_data.get('username')
'bob'
>>> cleaned_data['foo']
    Traceback (most recent call last):
      File "<stdin>", line 1, in <module>
    KeyError: 'foo'
>>> cleaned_data.get('foo')  # No exception, just get nothing back.
>>> cleaned_data.get('foo', "Sane Default")
'Sane Default'

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