How to debug Jinja2 template?

Question

I am using jinja2 template system into django. It is really fast and I like it a lot. Nevertheless, I have some problem to debug templates : If I make some errors into a template (bad tag, bad filtername, bad end of block...), I do not have at all information about this error.

For example, In a django view, I write this :

from jinja2 import Environment, PackageLoader env = Environment(loader=PackageLoader('main', 'templates'))  def jinja(req):     template = env.get_template('jinja.html')     output=template.render(myvar='hello')     return HttpResponse(output) 

I write a jinja2 template : jinja.html :

{{myvar|notexistingfilter()}} Jinja ! 

Notice, I put on purpose an non existing filter to generate an error :

I was expecting something like "notexistingfilter() not defined", but I got only a simple black on white traceback (not the usual django debug message) :

Traceback (most recent call last):    File "/usr/local/lib/python2.6/dist-packages/django/core/servers/basehttp.py", line 279, in run      self.result = application(self.environ, self.start_response)    File "/usr/local/lib/python2.6/dist-packages/django/core/servers/basehttp.py", line 651, in __call__     return self.application(environ, start_response)     File "/usr/local/lib/python2.6/dist-packages/django/core/handlers/wsgi.py", line 241, in __call__     response = self.get_response(request)    File "/usr/local/lib/python2.6/dist-packages/django/core/handlers/base.py", line 134, in get_response      return self.handle_uncaught_exception(request, resolver, exc_info)    File "/usr/local/lib/python2.6/dist-packages/django/core/handlers/base.py", line 154, in handle_uncaught_exception     return debug.technical_500_response(request, *exc_info)     File "/usr/local/lib/python2.6/dist-packages/django/views/debug.py", line 40, in technical_500_response     html = reporter.get_traceback_html()    File "/usr/local/lib/python2.6/dist-packages/django/views/debug.py", line 84, in get_traceback_html      self.get_template_exception_info()    File "/usr/local/lib/python2.6/dist-packages/django/views/debug.py", line 117, in get_template_exception_info     origin, (start, end) = self.exc_value.source    TypeError: 'Template' object is not iterable 

I do not get the template filename where the error occured, no information about the error itself, so it is very difficult to debug jinja2.

What should I do to have more debug information and find where an error is inside a jinja2 template ?

Thank you in advance,

Answer 1

After doing some more test, I found the answer :

By doing the same template test, directly under python, without using django, debug messages are present. So it comes from django.

The fix is in settings.py : One have to set DEBUG to True AND set TEMPLATE_DEBUG to False.