Django: display time it took to load a page on every page

Question

You can create a custom middleware to log this. Here is how I create a middleware to achieve this purpose base on http://djangosnippets.org/snippets/358/ (I modified the code a bit).

Firstly, assuming your project has a name: test_project, create a file name middlewares.py, I place it in the same folder as settings.py:

from django.db import connection
from time import time
from operator import add
import re


class StatsMiddleware(object):

    def process_view(self, request, view_func, view_args, view_kwargs):
        '''
        In your base template, put this:
        <div id="stats">
        <!-- STATS: Total: %(total_time).2fs Python: %(python_time).2fs DB: %(db_time).2fs Queries: %(db_queries)d ENDSTATS -->
        </div>
        '''

        # Uncomment the following if you want to get stats on DEBUG=True only
        #if not settings.DEBUG:
        #    return None

        # get number of db queries before we do anything
        n = len(connection.queries)

        # time the view
        start = time()
        response = view_func(request, *view_args, **view_kwargs)
        total_time = time() - start

        # compute the db time for the queries just run
        db_queries = len(connection.queries) - n
        if db_queries:
            db_time = reduce(add, [float(q['time'])
                                   for q in connection.queries[n:]])
        else:
            db_time = 0.0

        # and backout python time
        python_time = total_time - db_time

        stats = {
            'total_time': total_time,
            'python_time': python_time,
            'db_time': db_time,
            'db_queries': db_queries,
        }

        # replace the comment if found
        if response and response.content:
            s = response.content
            regexp = re.compile(r'(?P<cmt><!--\s*STATS:(?P<fmt>.*?)ENDSTATS\s*-->)')
            match = regexp.search(s)
            if match:
                s = (s[:match.start('cmt')] +
                     match.group('fmt') % stats +
                     s[match.end('cmt'):])
                response.content = s

        return response

Secondly, modify settings.py to add your middleware:

MIDDLEWARE_CLASSES = (
    'django.middleware.common.CommonMiddleware',
    'django.middleware.csrf.CsrfViewMiddleware',
    # ... your existing middlewares ...

    # your custom middleware here
    'test_project.middlewares.StatsMiddleware',
)

Note: you have to add the full path to your middleware class like above, the format is:

<project_name>.<middleware_file_name>.<middleware_class_name>

A second note is I added this middleware to the end of the list because I just want to log the template load time alone. If you want to log the load time of templates + all middlewares, please put it in the beginning of MIDDLEWARE_CLASSES list (credits to @Symmitchry).

Back to the main topic, the next step is to modify your base.html or whatever pages you want to log load time, add this:

<div id="stats">
<!-- STATS: Total: %(total_time).2fs Python: %(python_time).2fs DB: %(db_time).2fs Queries: %(db_queries)d ENDSTATS -->
</div>

Note: you can name the <div id="stats"> and use CSS for that div however you want, but DON’T change the comment . If you want to change it, be sure that you test it against the regex pattern in the created middlewares.py.

Voila, enjoy the statistics.

EDIT:

For those who use CBVs (Class Based Views) a lot, you might have encountered the error ContentNotRenderedError with above solution. Have no fear, here is the fix in middlewares.py:

    # replace the comment if found
    if response:
        try:
            # detects TemplateResponse which are not yet rendered
            if response.is_rendered:
                rendered_content = response.content
            else:
                rendered_content = response.rendered_content
        except AttributeError:  # django < 1.5
            rendered_content = response.content
        if rendered_content:
            s = rendered_content
            regexp = re.compile(
                r'(?P<cmt><!--\s*STATS:(?P<fmt>.*?)ENDSTATS\s*-->)'
            )
            match = regexp.search(s)
            if match:
                s = (s[:match.start('cmt')] +
                     match.group('fmt') % stats +
                     s[match.end('cmt'):])
                response.content = s

    return response

I got it working with Django 1.6.x, if you have problem with other version of Django, please ping me in comment section.

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