id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
16147	{% include %} tag raises TemplateDoesNotExist at compile time if TEMPLATE_DEBUG is True	Tai Lee	Aymeric Augustin	"I think this is a bug. Or at the very least, it can make for unexpected behaviour that is difficult to trace. When developing locally, `DEBUG` and `TEMPLATE_DEBUG` are often `True`. When `TEMPLATE_DEBUG` is `True`, compiling a template that contains an `{% include %}` to a template that doesn't exist will raise `TemplateDoesNotExist` at compile time of the parent template.

{{{
>>> from django.template import Template
>>> t = Template('{% include ""missing.html"" %}')
Traceback (most recent call last):
...
TemplateDoesNotExist: missing.html
}}}

The problem is that when you try to conditionally load a template, and perform a different action if it does not exist. For example, you might have a view that uses `select_template` to load one of several templates (if one exists) and send an email. If no email was sent (because no template exists), render a different template/context to the response or take some other action. If the email template contains a typo in the name of an included template, the email template will not be loaded and no email will be sent because `TemplateDoesNotExist` was raised.

In the local dev environment, this will not display a pretty debug page showing the error inside the email template, it will simply behave unexpectedly (by not sending an email when the email template DOES exist). On the production server (or when `TEMPLATE_DEBUG` is `False`), it will behave as expected. The email template will be found and it will be rendered.

This problem doesn't exist when using a variable as the template name.

{{{
>>> t = Template('{% include somevar %}')
>>> 
}}}

Why does Django try to execute the `{% include %}` when it contains a hard coded string at compile time at all? I think this is a case of premature optimisation. If it execution of the `{% include %}` was delayed until render time, `select_template` would correctly return the email template when `TEMPLATE_DEBUG` is `True`, and the proper error would be displayed in the rendered email template (making it an easy fix to correct the typo).
"	Bug	closed	Template system	dev	Normal	fixed	include template TemplateDoesNotExist TEMPLATE_DEBUG	prestontimmons@… anton@… FunkyBob	Ready for checkin	1	0	0	0	0	0