When is it appropriate to use Django context processors?

Question

If about half of my views require the same data set, is it appropriate to use a context processor to make the data always available, or is there a better way to avoid repeating the code to get that data across several views without querying the data if it won't be used in the view?

Answer 1

The RequestContext initializer will run any context processors listed in the settings file, but it also takes a list of additional processors to run. Any general purpose context processors can be put in settings.py and more specific ones can be added to the RequestContext on a case-by-case basis.

Leave RequestContext out altogether to not run any context processors.

# want context processors listed in settings.py as well as some more specific ones
return render_to_response('template.html', {'foo':'bar'}, context_instance=RequestContext(request, processors = extra_processors))

# want only context processors listed in settings.py
return render_to_response('template.html', {'foo':'bar'}, context_instance=RequestContext(request))

# no context processors
return render_to_response('template.html', {'foo':'bar'})

Answer 2

You can filter out which views actually use context processors by only passing RequestContext(request) only to those which need it, e.g.:

# want context processors
return render_to_response('template.html', {'foo':'bar'}, context_instance=RequestContext(request))

# no context processors
return render_to_response('template.html', {'foo':'bar'})