Django Debug Toolbar

As explained in Django in Action

Django Debug Toolbar is a Django add-on that displays diagnostic information about request processing, performance, and resources used to generate a response.

Django Debug Toolbar is a development-server overlay that exposes what happens while Django builds a response. It helps turn a vague complaint such as “this page feels slow” into evidence about execution time, SQL queries, HTTP requests, templates, and other resources. section 13.0 section 13.6

Install and configure it as a Django app:

• Install the package with python -m pip install django-debug-toolbar. section 13.1
• Ensure django.contrib.staticfiles is installed, STATIC_URLS is configured, and APP_DIRS is True in TEMPLATES. section 13.1
• Add debug_toolbar to INSTALLED_APPS and debug_toolbar.middleware.DebugToolbarMiddleware to MIDDLEWARE, placing the middleware as high as possible after encoding middleware such as GZipMiddleware. section 13.1
• Add path("__debug__/", include("debug_toolbar.urls")) to urls.py and add 127.0.0.1 to INTERNAL_IPS. section 13.1

After configuration, run the development server and visit a page such as /bands/musicians/. A callout appears on the right, containing panels that report different parts of request processing. The panels can be customized, and third-party additions are possible. section 13.1

Figure 13.1 Django Debug Toolbar on the musician listing page

Use the musician-listing screenshot to recognize the toolbar overlay and its position on a rendered Django page. section 13.1

Table 13.1 Django Debug Toolbar panels

Panel	Description
History	History of requests made, which also includes the ability to view the debug info for past visits
Versions	Shows the versions of Django, Python, and installed apps (if possible)
Timer	Shows page load time information, including CPU time, system time, and a graph showing the timing for each step in processing the page
Settings	Shows your current project configuration values
Headers	Request and response headers along with WSGI environment information
Request	Information about the HTTP request, including the view function invoked, any cookies, session data, and data for the GET or POST
SQL	SQL queries run to get the page’s data along with timing information
Static files	Information on the static files used on the page along with all the possible files available to the {% static %} tag
Templates	Shows the template path and all templates involved in rendering this page
Cache	Whether the cache got used along with hit-and-miss counts and response times
Signals	All the Django signals registered and their associated handlers
Intercept redirects	If a page issues a redirect, the toolbar catches it and shows a page with the resulting link (panel off, by default)
Profiling	Complete profile information on the request, including all the functions called and their timings (panel off by default)

Use the panel table as a quick map from a symptom to evidence: Timer covers processing time, SQL covers database queries, Request covers HTTP and view details, and Templates and Static files cover rendering resources. section 13.1

Investigating a slow page

Open the page, inspect the Timer panel for load and processing information, then inspect SQL for query timing. Use Request to check the invoked view and request data, and Templates or Static files to examine rendering resources. This combination supplies concrete clues instead of relying on guesswork. section 13.6 section 13.1

How Django in Action covers it

How deep it goes

Explains installation, settings, middleware, routing, security, panels, and slow-page investigation, but defers complete version-specific installation details.

Examples

Uses the RiffMates musician listing, a development-server overlay, and panels for timing, SQL, requests, templates, and static files.

What it assumes

Assumes a Django project with development-server settings while identifying required staticfiles, templates, middleware, URLs, and local IP configuration.

What you can do after

Diagnose slow Django pages by correlating timing, SQL, request, template, and static-file evidence.

How it connects

Connects Django views with middleware, URL routing, settings, HTTP requests, SQL queries, templates, static files, and profiling.

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Related concepts

• dependencykind of · A software dependency is a component, resource, or prerequisite on which another software component or operation relies to function or proceed.
• view functionuses · A view function is a web request handler associated with a route that receives a request and returns an HTTP response.
• Djangouses · Django is an open-source Python web framework providing integrated components for developing structured, database-backed web applications and services.
• debug toolbar panelhas part · A Django Debug Toolbar panel is a configurable diagnostic component that displays a category of information about a request or view execution.

This explainer was generated by Manning's knowledge graph from the text of Django in Action. The section links point to the parts of the book it draws on.