How to store an instance of a Class into a file

Question

This has been bugging me for a while. I can't find anything online that gives me an answer I am looking for. Hopefully you guys canshed some light on this:

Here is a piece of code:

class MyClass():
    def __init__(self):
        self.name = ''
        self.age = 0
        self.gender = ''


me = MyClass()
me.name = "john"
me.age = 23
me.gender = "male"

with open('MyFile', 'w') as f:
    dict = vars(me)
    for attr in dict:
        f.write(att + '\n')

Output:

name
age
gender

How i want the output to be like...

name: john
age: 23
gender: male

the format doesn't matter, but something where I can store an instance of a class in a file to be able to read from again.. Anyone have any ideas?

You want to read about serializers https://docs.python.org/2.7/library/pickle.html — matcheek, Aug 14 '14 at 20:27
There are so many different ways to do this. Should the file be human-readable? Consider e.g. a JSON representation. If not, `pickle` is probably the lowest-effort. — jonrsharpe, Aug 14 '14 at 20:28
Possible duplicate: http://stackoverflow.com/q/4529815/3001761 — jonrsharpe, Aug 14 '14 at 20:36

score 1 · Accepted Answer · answered Aug 14 '14 at 20:34

1

Pickle!

#save
file_handler = open("myfile.pkl", "w")
pickle.dump(me, file_handler)

#load
file_handler = open("myfile.pkl", "r")
me = pickle.load(file_handler)

answered Aug 14 '14 at 20:34

katerinah

111
4

I can't give more than one argument when i do pickle.load? – pypy Aug 14 '14 at 20:43
You can pickle a list or dictionary of picklable objects. Or just one object. – katerinah Aug 15 '14 at 01:46

score 0 · Answer 2 · edited Aug 14 '14 at 20:27

0

You could roll your own, or you could try pickle. This question has been answered before though.

edited Aug 14 '14 at 20:27

enrico.bacis

30,497
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answered Aug 14 '14 at 20:24

jgritty

11,660
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can you please provide a link, I haven't been able to find anything online that solves this. Maybe I am wording my question wrong. – pypy Aug 14 '14 at 20:26

score 0 · Answer 3 · edited Aug 14 '14 at 20:36

0

You should try pickle, but I think what you are looking for is just to make your code

with open('MyFile', 'w') as f:
    dict = vars(me)
    for attr in dict:
        f.write( attr + ': ' + str( dict[attr] ) + '\n')

edited Aug 14 '14 at 20:36

Romasz

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answered Aug 14 '14 at 20:26

nair.ashvin

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thank you yes that is was I am looking for, although I will try to go into pickle, because these things are going to be stored to be read from again. – pypy Aug 14 '14 at 20:28

How to store an instance of a Class into a file

3 Answers3