Provide extra context to all views

Question

I'm putting together a project management website for my team using django. My base template includes a sidebar menu which contains a list of all projects and users, linking to a DetailView for that user or project, respectively.

My problem is that I need to provide the User and Project models to every view so that I can render that sidebar. I know how to add extra context; the problem is that I feel like I'm violating DRY by modifying the context at each level. Is it possible to simply redefine the base TemplateClass so that all child classes—ListView, DetailView, etc.—contain the modified context?

On a related note, if this is a terrible way to set up the project, let me know that as well.

Answer 1

You could use the template context processor:

myapp/context_processors.py:

from django.contrib.auth.models import User
from myapp.models import Project

def users_and_projects(request):
    return {'all_users': User.objects.all(),
            'all_projects': Project.objects.all()}

And then add this processor to the TEMPLATE_CONTEXT_PROCESSORS setting for Django version < 1.8:

TEMPLATE_CONTEXT_PROCESSORS = (
    ...
    'myapp.context_processors.users_and_projects',
)

And for Django version >= 1.8 add it to the context_processors list in the OPTIONS of the TEMPLATES setting:

TEMPLATES = [
    {
        ...
        'OPTIONS': {
            'context_processors': [
                ...
                'myapp.context_processors.users_and_projects',
            ],
        },
    },
]

Context processor will run for ALL your requests. If your want to run these queries only for views which use the base.html rendering then the other possible solution is the custom assignment tag:

@register.assignment_tag
def get_all_users():
    return User.objects.all()

@register.assignment_tag
def get_all_projects():
    return Project.objects.all()

And the in your base.html template:

{% load mytags %}

{% get_all_users as all_users %}
<ul>
{% for u in all_users %}
    <li><a href="{{ u.get_absolute_url }}">{{ u }}</a></li>
{% endfor %}
</ul>

{% get_all_projects as all_projects %}
<ul>
{% for p in all_projects %}
    <li><a href="{{ p.get_absolute_url }}">{{ p }}</a></li>
{% endfor %}
</ul>