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Assigning a Django Model's field to a value if it matches a condition.
g = Car.objects.get(pk=1234)
g.data_version = my_dict['dataVersion'] if my_dict else expression_false # Do nothing??
How do I do nothing in that case? We can't do if conditional else pass.
I know I can do:
if my_dict:
g.data_version = my_dict['dataVersion']
but I was wondering if there was a way to do inline expression_true if conditional else do nothing.
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pass is a special statement in Python that does nothing. It only works as a dummy statement. We can use pass in empty while statement also. We can use pass in empty if else statements.
Use an inline if-else expressionUse the syntax statement1 if condition else statement2 to execute statement1 if condition is True otherwise execute statement2 if condition evaluates to False .
An if statement looks at any and every thing in the parentheses and if true, executes block of code that follows. If you require code to run only when the statement returns true (and do nothing else if false) then an else statement is not needed.
Answer: Yes, we can use if-else in one line. In Python, we can convert if-else into one conditional statement.
No, you can't do exactly what you are describing, as it wouldn't make sense. You are assigning to the variable g.data_version... so you must assign something. What you describe would be like writing:
g.data_version = # There is nothing else here
Which is obviously invalid syntax. And really, there's no reason to do it. You should either do:
if my_dict:
g.data_version = my_dict['dataVersion']
or
g.data_version = my_dict['dataVersion'] if my_dict else None # or 0 or '' depending on what data_version should be.
Technically, you could also do:
g.data_version = my_dict['dataVersion'] if my_dict else g.data_version
if you only want to update g.data_version if your dict exists, but this is less readable and elegant than just using a normal if statement.
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