我有一个dict,其中我加载了一些信息,其中一个名称是一个普通的字符串.但不知何故,当我将它分配给dict中的一个键时,它会转换为一个元组,我不知道为什么.

这是我的一些代码：

sentTo = str(sentTo)
print type(sentTo), sentTo
ticketJson['sentTo'] = sentTo,
print type(ticketJson['sentTo']), ticketJson['sentTo']

在我的终端输出以下内容：

<type 'str'> Pete Chasin
<type 'tuple'> ('Pete Chasin',)

为什么将它分配给dict会将其转换为元组？

解决方法:

你告诉Python创建一个包含字符串的元组：

ticketJson['sentTo'] = sentTo,
#                            ^

它是定义元组的逗号.只需要括号来消除元组与逗号的其他用法的歧义,例如在函数调用中.

从Parenthesized forms section：

Note that tuples are not formed by the parentheses, but rather by use of the comma operator. The exception is the empty tuple, for which parentheses are required — allowing unparenthesized “nothing” in expressions would cause ambiguities and allow common typos to pass uncaught.

从Expression lists开始：

An expression list containing at least one comma yields a tuple. The length of the tuple is the number of expressions in the list. The expressions are evaluated from left to right.