Convert Unicode data to int in python

Question

I am getting values passed from url as :

user_data = {}
if (request.args.get('title')) :
    user_data['title'] =request.args.get('title')
if(request.args.get('limit')) :
    user_data['limit'] =    request.args.get('limit')

Then using it as

if 'limit' in user_data :
    limit = user_data['limit']
conditions['id'] = {'id':1}
int(limit)
print type(limit)
data = db.entry.find(conditions).limit(limit)

It prints : <type 'unicode'>

but i keep getting the type of limit as unicode, which raises an error from query!! I am converting unicode to int but why is it not converting?? Please help!!!

score 54 · Accepted Answer · edited Oct 26 '17 at 20:53

54

int(limit) returns the value converted into an integer, and doesn't change it in place as you call the function (which is what you are expecting it to).

Do this instead:

limit = int(limit)

Or when definiting limit:

if 'limit' in user_data :
    limit = int(user_data['limit'])

edited Oct 26 '17 at 20:53

Elis Byberi

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answered May 10 '13 at 06:34

TerryA

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+1 And by `doesn't change it immediately` meaning it doesn't change it by reference. – Jared May 10 '13 at 06:39
@Jared I'll add this, thanks :). I knew my wording wasn't perfect in some way :p – TerryA May 10 '13 at 06:40
@MANCHUCK Don't worry about it :) – TerryA Jul 12 '16 at 22:46

score 7 · Answer 2 · edited May 23 '17 at 12:02

In python, integers and strings are immutable and are passed by value. You cannot pass a string, or integer, to a function and expect the argument to be modified.

So to convert string limit="100" to a number, you need to do

limit = int(limit) # will return new object (integer) and assign to "limit"

If you really want to go around it, you can use a list. Lists are mutable in python; when you pass a list, you pass it's reference, not copy. So you could do:

def int_in_place(mutable):
    mutable[0] = int(mutable[0])

mutable = ["1000"]
int_in_place(mutable)
# now mutable is a list with a single integer

But you should not need it really. (maybe sometimes when you work with recursions and need to pass some mutable state).

Convert Unicode data to int in python

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