Django context variable in the navigation bar - correct href assignment?

Question

What is the correct assignment of context variables in the navigation bar? My Django example is:

in view.py:

from django.shortcuts import render
from django.http import HttpResponse 

context_navigation =   {
           'Link1'    : 'Blog',
           'href1'    : "{% url 'blog' %}",   }

def index(request):
    return render(request, 'app_about/index.html', context=context_navigation)  
    

in urls.py:

from django.urls import path
from . import views

urlpatterns = [ 
    path('blog/', views.index, name='blog'),  
    ]
    

in templates/base.html this does work

<a class="nav-item nav-link text-light"  href="{% url 'blog' %}" > {{Link1}}</a>

this does not work (see href1 and Link1)

<a class="nav-item nav-link text-light"  href="{{href1}}" > {{Link1}}</a>

In the last case a wrong url is generated, something like http://127.0.0.1:8000/blog/%7B%. What is the correct assignment of href as a context variable href1 ? Thank you for some hints!

Answer 1

In the second example you insert a variable href1, which is replaced by the content (the string) {% url 'blog %} when rendered. Django trys to render this string (makes it html safe, thats where the %7B.. came from, which is just the html code for {.

Option 1: resolve url in the view

You can either resolve the url using python in the view and pass the actual url as string to the template:

views.py

from django.urls import reverse

context_navigation =   {
       'Link1'    : 'Blog',
       'href1'    : reverse('blog')
}

base.html

<a class="nav-item nav-link text-light"  href="{{href1}}">{{Link1}}</a>

Option 2: resolve url in the template

Or you go with the first example, where {% url 'blog %} will be interpreted and executed by the template rendering engine:

context_navigation =   {
       'Link1'    : 'Blog'
}

base.html

<a class="nav-item nav-link text-light"  href="{% url 'blog' %}">{{Link1}}</a>

Option3: view passes url (name) and template resolves it (not tested)

If you need to generate the context dynamically but want to resolve the actual urls in the template you can maybe pass the url name as variable like:

context_navigation =   {
       'Link1': 'Blog',
       'url1': 'blog',
}

base.html

<a class="nav-item nav-link text-light"  href="{% url url1 %}">{{Link1}}</a>

But I'm not sure if you can use varaibles in template tags like this (just a guess, never used it this way)