Python - How to concatenate Strings and Integers in Python?

Question

I'm with some trouble getting this code to work:

count_bicycleadcategory = 0
for item_bicycleadcategory in some_list_with_integers:
    exec 'model_bicycleadcategory_%s.bicycleadcategorytype = BicycleAdCategoryType.objects.get(pk=' + str(item_bicycleadcategory) + ')' % count_bicycleadcategory
    count_bicycleadcategory = count_bicycleadcategory + 1

I'm getting an error:

Type Error, not all arguments converted during string formatting

My question is: Any clue on how I pass the "item_bicycleadcategory" to the exec expression?

Best Regards,

This is wrong, wrong, wrong. Why do you think you need dynamic variable names? You do not. You need a single dictionary. — Daniel Roseman
– Daniel Roseman, Commented Jan 6, 2013 at 19:51
Is this just a very unsafe and obscure way of writing (or meant to be): values = {pk: BicycleAdCategoryType.objects.get(pk=pk) for pk in some_list_with_integers} ? — Jon Clements
– Jon Clements, Commented Jan 6, 2013 at 20:00
Or thinking about it a bit more... BicycleAdCategoryType.objects.get(pk__in=some_list_with_integers)? — Jon Clements
– Jon Clements, Commented Jan 6, 2013 at 20:11

emil · Accepted Answer · 2013-01-06 19:04:46Z

3

You are already using python's format syntax:

"string: %s\ndecimal: %d\nfloat: %f" % ("hello", 123, 23.45)

More info here: http://docs.python.org/2/library/string.html#format-string-syntax

answered Jan 6, 2013 at 19:04

emil

1,70013 silver badges12 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Fredrick Brennan · Accepted Answer · 2013-01-06 19:13:48Z

2

First, exec is even more dangerous than eval(), so be absolutely sure that your input is coming from a trusted source. Even then, you shouldn't do it. It looks like you're using a web framework or something of the sort, so really don't do it!

The problem is this:

exec 'model_bicycleadcategory_%s.bicycleadcategorytype = BicycleAdCategoryType.objects.get(pk=' + str(item_bicycleadcategory) + ')' % count_bicycleadcategory

Take a closer look. You're trying to put the string formatting argument to a single parentesis with no format strings with ')' % count_bicycleadcategory.

You could do this:

exec 'model_bicycleadcategory_%s.bicycleadcategorytype = BicycleAdCategoryType.objects.get(pk=' % count_bicycleadcategory + str(item_bicycleadcategory) + ')'

But what you really should be doing is not using exec at all!

Create a list of your model instances and use that instead.

answered Jan 6, 2013 at 19:13

Fredrick Brennan

7,3533 gold badges35 silver badges67 bronze badges

1 Comment

poke Over a year ago

+1 for actually responding to the error message; also for the exec warning.

Dmitry Zagorulkin · Accepted Answer · 2013-01-06 20:54:51Z

1

for python 2.7 you could use format:

string = '{0} give me {1} beer'
string.format('Please', 3)

out:

Please give me 3 beer

you could do many things with format, for example:

string = '{0} give me {1} {0} beer'

out:

Please give me 3 Please beer.

edited Jan 6, 2013 at 20:54

answered Jan 6, 2013 at 19:10

Dmitry Zagorulkin

8,5584 gold badges39 silver badges63 bronze badges

Comments

MBarsi · Accepted Answer · 2013-01-06 19:12:48Z

-1

try this :

exec 'model_bicycleadcategory_%s.bicycleadcategorytype = BicycleAdCategoryType.objects.get(pk=%s)' % (count_bicycleadcategory, str(item_bicycleadcategory))

(you mustn't mix %s and string + concatenation at the same time)

answered Jan 6, 2013 at 19:12

MBarsi

2,4671 gold badge18 silver badges18 bronze badges

Comments

Alex G.P. · Accepted Answer · 2013-01-06 19:10:07Z

-2

Try this:

exec 'model_bicycleadcategory_%d.bicycleadcategorytype = BicycleAdCategoryType.objects.get(pk=%d)' % (count_bicycleadcategory, item_bicycleadcategory)

answered Jan 6, 2013 at 19:10

Alex G.P.

10.1k6 gold badges50 silver badges88 bronze badges

Collectives™ on Stack Overflow

Python - How to concatenate Strings and Integers in Python?

5 Answers 5

Comments

1 Comment

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

5 Answers 5

Comments

1 Comment

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related