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DebugFooter middleware with Pygments sql syntax highlighting

Author:
monolar
Posted:
June 13, 2008
Language:
Python
Version:
.96
Score:
2 (after 2 ratings)

Based on Snippet 766 but added syntax highlighting of the sql output via pygments. The sql output will also be wrapped at 120 characters by default (can be configured by changing WRAP). It degrades nicely if pygments is not installed. This will add quite some cpu-cycles just for printing debug messages so use with care.

Following is the rest of the original description by simon (shamelessly copied):

Adds a hidden footer to the bottom of every text/html page containing a list of SQL queries executed and templates that were loaded (including their full filesystem path to help debug complex template loading scenarios).

To use, drop into a file called 'debug_middleware.py' on your Python path and add 'debug_middleware.DebugFooter' to your MIDDLEWARE_CLASSES setting.

Edit: Added the ability to set the height of the debug-box

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#!/usr/bin/env python
# -*- coding: utf-8 -*-

import time
from django.dispatch import dispatcher
from django.core.signals import request_started
from django.test.signals import template_rendered
from django.conf import settings
from django.db import connection
from django.utils.encoding import force_unicode
from django.utils.safestring import mark_safe

USE_PYGMENTS = False
try:
    import textwrap
    from pygments import highlight
    from pygments.formatters import HtmlFormatter
    from pygments.lexers import SqlLexer
    from pygments.styles import get_style_by_name    
    USE_PYGMENTS = True
except ImportError:
    pass

if USE_PYGMENTS:
    WRAP = 120
    STYLE = get_style_by_name('colorful')

HEIGHT = '240px' # or '100%' if full height is wished

TEMPLATE = """
<div id="debug" style="clear:both;">
<a href="#debugbox"
    onclick="this.style.display = 'none';   
        document.getElementById('debugbox').style.display = 'block';
        return false;"
    style="font-size: small; color: red; text-decoration: none; display: block; margin: 12px;"
>+</a>

<div style="display: none;clear: both; border: 1px solid red; padding: 12px; {{ height }} margin: 12px; overflow: auto;"
     id="debugbox">

<p>Server-time taken: {{ server_time|floatformat:"5" }} seconds</p>
<p>Templates used:</p>
{% if templates %}
<ol>
    {% for template in templates %}
        <li><strong>{{ template.0 }}</strong> loaded from <samp>{{ template.1 }}</samp></li>
    {% endfor %}
</ol>
{% else %}
    None
{% endif %}
<p>Template path:</p> 
{% if template_dirs %}
    <ol>
    {% for template in template_dirs %}
        <li>{{ template }}</li>
    {% endfor %}
    </ol>
{% else %}
    None
{% endif %}
<p>SQL executed:</p>
{% if sql %}
<ol>
{% for query in sql %}
    <li><pre>{{ query.sql|linebreaksbr }}</pre><p>took {{ query.time|floatformat:"3" }} seconds</p></li>
{% endfor %}
</ol>
<p>Total SQL time: {{ sql_total }}</p>
{% else %}
    None
{% endif %}
</div>
</div>
</body>
"""

# Monkeypatch instrumented test renderer from django.test.utils - we could use
# django.test.utils.setup_test_environment for this but that would also set up
# e-mail interception, which we don't want
from django.test.utils import instrumented_test_render
from django.template import Template, Context
if Template.render != instrumented_test_render:
    Template.original_render = Template.render
    Template.render = instrumented_test_render
# MONSTER monkey-patch
old_template_init = Template.__init__
def new_template_init(self, template_string, origin=None, name='<Unknown Template>'):
    old_template_init(self, template_string, origin, name)
    self.origin = origin
Template.__init__ = new_template_init

class DebugFooter:
    def process_request(self, request):
        self.time_started = time.time()
        self.templates_used = []
        self.contexts_used = []
        self.sql_offset_start = len(connection.queries)
        dispatcher.connect(
            self._storeRenderedTemplates, signal=template_rendered
        )
        
    def process_response(self, request, response):
        # Only include debug info for text/html pages not accessed via Ajax
        if 'text/html' not in response['Content-Type']:
            return response
        if request.is_ajax():
            return response
        if not settings.DEBUG:
            return response
        if response.status_code != 200:
            return response
        
        templates = [
            (t.name, t.origin and t.origin.name or 'No origin')
            for t in self.templates_used
        ]
        sql_queries = connection.queries[self.sql_offset_start:]
        # Reformat sql queries a bit
        sql_total = 0.0
        
        for query in sql_queries:
            query['sql'] = highlight_sql(query['sql'])
            sql_total += float(query['time'])
        
        #import pdb; pdb.set_trace()
        
        
        debug_content = Template(TEMPLATE).render(Context({
            'server_time': time.time() - self.time_started,
            'templates': templates,
            'sql': sql_queries,
            'sql_total': sql_total,
            'template_dirs': settings.TEMPLATE_DIRS,
            'height': 'height: %s;' % (HEIGHT, ),
        }))
        
        content = response.content
        response.content = force_unicode(content).replace('</body>', debug_content)
        
        #import pdb; pdb.set_trace()
        return response
    
    def _storeRenderedTemplates(self, signal, sender, template, context):
        self.templates_used.append(template)
        self.contexts_used.append(context)

def highlight_sql(sql):
    if USE_PYGMENTS:
        sql = mark_safe(highlight(textwrap.fill(sql, WRAP),
                                  SqlLexer(encoding='utf-8'),
                                  HtmlFormatter(encoding='utf-8',
                                                noclasses=True,
                                                style=STYLE)
                                  )
                        )
    else:
        sql = reformat_sql(sql)
    return sql

def reformat_sql(sql):
    sql = sql.replace('`,`', '`, `')
    sql = sql.replace('` FROM `', '` \n  FROM `')
    sql = sql.replace('` WHERE ', '` \n  WHERE ')
    sql = sql.replace(' ORDER BY ', ' \n  ORDER BY ')
    return sql

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