casting - Python cast string to type if string is not none -

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• python idiom applying function when value not none 2 answers

i have long list of values cast , assign. each value has possibility of being none. if value none, i'd leave none, otherwise casting. reason being these values end in database , have convert none's null's later.

so far simplest way i've found adding inline if statements each assignment.

self.number = decimal(input.number) if input.number else none 

i don't find code appealing, it's lacking in readability , tedious write statements on every input value. prefer decimal(input.number) return none if input.number none doesn't appear case. there simpler way this? suppose make own decimal_ function , call instead?

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update:

i've heeded words of advice hear , come this

def dec_(string):     if string none:         return none     else:         try:             return decimal.decimal(string)         except:             return none .....  self.number = dec_(input.number) 

now need make cast wrapper each type of cast need do.

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update2:

i think should work same running try block in dec_

def dec_(string):     try:         return decimal.decimal(string)     except:         return none 

there no built in way easier you've discovered. writing own function the approved way reduce code duplication , increase readability repeated tasks.

however, note code , description don't quite match up: chr(input.something) if input.something else none give none if input.something falsely value, such 0 or empty string - test explicitly input.something not none if that's mean.