Python 检查 Django 中是否设置了会话密钥
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Check if Session Key is Set in Django
提问by Julio
I am attempting to create a relatively simple shopping cart in Django. I am storing the cart in request.session['cart']. Therefore, I'll need to access the data in this session when anything is added to it. However, if the session is not already set, I cannot access it without receiving an error. Is there anyway to check if a session is set, so that it can be set if it doesn't exist?
我正在尝试在 Django 中创建一个相对简单的购物车。我将购物车存储在 request.session['cart'] 中。因此，当向其中添加任何内容时，我需要访问此会话中的数据。但是，如果会话尚未设置，我将无法访问它而不会收到错误消息。无论如何要检查是否设置了会话，以便在它不存在时可以设置它？
采纳答案by Manoj Govindan
I assume that you want to check if a keyis set in session, not if a sessionis set (don't know what the latter means). If so:
我假设您想检查是否在会话中设置了密钥，而不是是否设置了会话（不知道后者是什么意思）。如果是这样的话：
You can do:
你可以做：
if key not in request.session:
# Set it.
In your case:
在你的情况下：
if 'cart' not in request.session:
# Set it.
EDIT: changed the code snippet to use key not inrather than not key in. Thanks @katrielalex.
编辑：将代码片段更改为 usekey not in而不是not key in. 谢谢@katrielalex。
回答by Bernhard Vallant
You can use the get-method on the session dictionary, it will not throw an error if the key doesn't exist, but return none as a default value or your custom default value:
您可以get在会话字典上使用-method，如果键不存在，它不会抛出错误，但返回 none 作为默认值或您的自定义默认值：
cart = request.session.get('cart')
cart = request.session.get('cart', 'no cart')
