Why does format() break this Python string?

Asked Sep 13 '16 at 08:35

Active Sep 13 '16 at 08:38

Viewed 54 times

I can't figure out why the following string is broken:

print '{% extends \"{base_route_name}.html\" %}'.format(base_route_name='base')

It returns the following error:

KeyError: '% extends "{base_route_name}'

I've tried using double %% as suggested in answers to this question and other escaping measures to no avail.

The only way I was able to fix it was to do this:

print '{% extends \"' + base_route_name + '.html\" %}'

Any ideas why using format() wasn't working?

edited May 23 '17 at 10:29

Community

asked Sep 13 '16 at 08:35

Blairg23

4

Because the `{` and `}` characters are the metacharacters in `str.format()`, not `%`. – Martijn Pieters Sep 13 '16 at 08:36
1

You also don't need to escape `"` characters if you're using `'` for strings. – Holloway Sep 13 '16 at 08:39
1

It looks like you're creating a string for a templating engine... if so, you should be using that to handle placeholders... – Jon Clements Sep 13 '16 at 08:39
I'm actually creating pages dynamically outside of the web app and this particular placeholder is generated using specific parameters. – Blairg23 Sep 14 '16 at 07:26

0 Answers0