Justin Thurman
Today I Learned

Today I Learned

About the _ Variable in Python

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Justin Thurman
·Jan 6, 2022·

When using Python in an interactive environment (i.e., the shell), the _ variable stores the result of your most recent operation. This is useful if, like me, you spend a fair amount of time in the Django shell when writing/debugging features.

For example, you can do something like this.

>>> User.objects.last()
<User: username>
>>> _.first_name
'Bob'

Of course, you could have just run User.objects.last().first_name to begin with, but in a real-world scenario, I often find myself iteratively building querysets, e.g., running one queryset, seeing what it returns, tacking on another queryset method, and so on.

The _ variable can make this process a lot easier, especially if you use multiline arguments to, e.g., filter and so can't easily use shell history to rerun your previous command.

 
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