Django Debug Toolbar

The Django Debug Toolbar is a configurable set of panels that display various debug information about the current request/response and when clicked, display more details about the panel's content.

Currently, the following panels have been written and are working:

Django version
Request timer
A list of settings in settings.py
Common HTTP headers
GET/POST/cookie/session variable display
Templates and context used, and their template paths
SQL queries including time to execute and links to EXPLAIN each query
List of signals, their args and receivers
Logging output via Python's built-in logging, or via the logbook module

There is also one Django management command currently:

debugsqlshell: Outputs the SQL that gets executed as you work in the Python interactive shell. (See example below)

If you have ideas for other panels please let us know.

Note: The Debug Toolbar only works on Django 1.2 and newer.

Installation

Add the debug_toolbar directory to your Python path.
Add the following middleware to your project's settings.py file:
```
MIDDLEWARE_CLASSES = (
    # ...
    'debug_toolbar.middleware.DebugToolbarMiddleware',
    # ...
)
```
Tying into middleware allows each panel to be instantiated on request and rendering to happen on response.

The order of MIDDLEWARE_CLASSES is important: the Debug Toolbar middleware must come after any other middleware that encodes the response's content (such as GZipMiddleware).

Note: The debug toolbar will only display itself if the mimetype of the response is either text/html or application/xhtml+xml and contains a closing </body> tag.

Note: Be aware of middleware ordering and other middleware that may intercept requests and return responses. Putting the debug toolbar middleware after the Flatpage middleware, for example, means the toolbar will not show up on flatpages.
Make sure your IP is listed in the INTERNAL_IPS setting. If you are working locally this will be:
```
INTERNAL_IPS = ('127.0.0.1',)
```
Note: This is required because of the built-in requirements of the show_toolbar method. See below for how to define a method to determine your own logic for displaying the toolbar.
Add debug_toolbar to your INSTALLED_APPS setting so Django can find the template files associated with the Debug Toolbar:
```
INSTALLED_APPS = (
    ...
    'debug_toolbar',
)
```

Configuration

The debug toolbar has two settings that can be set in settings.py:

Optional: Add a tuple called DEBUG_TOOLBAR_PANELS to your settings.py file that specifies the full Python path to the panel that you want included in the Toolbar. This setting looks very much like the MIDDLEWARE_CLASSES setting. For example:

DEBUG_TOOLBAR_PANELS = (
    'debug_toolbar.panels.version.VersionDebugPanel',
    'debug_toolbar.panels.timer.TimerDebugPanel',
    'debug_toolbar.panels.settings_vars.SettingsVarsDebugPanel',
    'debug_toolbar.panels.headers.HeaderDebugPanel',
    'debug_toolbar.panels.request_vars.RequestVarsDebugPanel',
    'debug_toolbar.panels.template.TemplateDebugPanel',
    'debug_toolbar.panels.sql.SQLDebugPanel',
    'debug_toolbar.panels.signals.SignalDebugPanel',
    'debug_toolbar.panels.logger.LoggingPanel',
)

You can change the ordering of this tuple to customize the order of the panels you want to display, or add/remove panels. If you have custom panels you can include them in this way -- just provide the full Python path to your panel.

Optional: There are a few configuration options to the debug toolbar that can be placed in a dictionary called DEBUG_TOOLBAR_CONFIG:
- INTERCEPT_REDIRECTS
  
  If set to True (default), the debug toolbar will show an intermediate page upon redirect so you can view any debug information prior to redirecting. This page will provide a link to the redirect destination you can follow when ready. If set to False, redirects will proceed as normal.
- SHOW_TOOLBAR_CALLBACK
  
  If not set or set to None, the debug_toolbar middleware will use its built-in show_toolbar method for determining whether the toolbar should show or not. The default checks are that DEBUG must be set to True or the IP of the request must be in INTERNAL_IPS. You can provide your own method for displaying the toolbar which contains your custom logic. This method should return True or False.
- EXTRA_SIGNALS
  
  An array of custom signals that might be in your project, defined as the python path to the signal.
- HIDE_DJANGO_SQL
  
  If set to True (the default) then code in Django itself won't be shown in SQL stacktraces.
- SHOW_TEMPLATE_CONTEXT
  
  If set to True (the default) then a template's context will be included with it in the Template debug panel. Turning this off is useful when you have large template contexts, or you have template contexts with lazy datastructures that you don't want to be evaluated.
- TAG
  
  If set, this will be the tag to which debug_toolbar will attach the debug toolbar. Defaults to 'body'.
- ENABLE_STACKTRACES
  
  If set, this will show stacktraces for SQL queries and cache calls. Enabling stacktraces can increase the CPU time used when executing queries. Defaults to True.
Example configuration:
```
def custom_show_toolbar(request):
    return True  # Always show toolbar, for example purposes only.

DEBUG_TOOLBAR_CONFIG = {
    'INTERCEPT_REDIRECTS': False,
    'SHOW_TOOLBAR_CALLBACK': custom_show_toolbar,
    'EXTRA_SIGNALS': ['myproject.signals.MySignal'],
    'HIDE_DJANGO_SQL': False,
    'TAG': 'div',
    'ENABLE_STACKTRACES' : True,
}
```

`debugsqlshell`

The following is sample output from running the debugsqlshell management command. Each ORM call that results in a database query will be beautifully output in the shell:

$ ./manage.py debugsqlshell
Python 2.6.1 (r261:67515, Jul  7 2009, 23:51:51)
[GCC 4.2.1 (Apple Inc. build 5646)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
(InteractiveConsole)
>>> from page.models import Page
>>> ### Lookup and use resulting in an extra query...
>>> p = Page.objects.get(pk=1)
SELECT "page_page"."id",
       "page_page"."number",
       "page_page"."template_id",
       "page_page"."description"
FROM "page_page"
WHERE "page_page"."id" = 1

>>> print p.template.name
SELECT "page_template"."id",
       "page_template"."name",
       "page_template"."description"
FROM "page_template"
WHERE "page_template"."id" = 1

Home
>>> ### Using select_related to avoid 2nd database call...
>>> p = Page.objects.select_related('template').get(pk=1)
SELECT "page_page"."id",
       "page_page"."number",
       "page_page"."template_id",
       "page_page"."description",
       "page_template"."id",
       "page_template"."name",
       "page_template"."description"
FROM "page_page"
INNER JOIN "page_template" ON ("page_page"."template_id" = "page_template"."id")
WHERE "page_page"."id" = 1

>>> print p.template.name
Home

Running the Tests

The Debug Toolbar includes a limited (and growing) test suite. If you commit code, please consider adding proper coverage (especially if it has a chance for a regression) in the test suite.

python setup.py test

3rd Party Panels

A list of 3rd party panels can be found on the Django Debug Toolbar Github wiki: https://github.com/django-debug-toolbar/django-debug-toolbar/wiki/3rd-Party-Panels

TODOs and BUGS

See: https://github.com/django-debug-toolbar/django-debug-toolbar/issues

acdha/django-debug-toolbar