Question

Every time I code something using Django, I am faced to the same issue (I think this is due to my lack of experience using this framework):

I know how to pass arguments I had from a queryset to a template and how to display it but I don’t know how to add argument computed in the view and use them in the template.

Simple View (I master it) :
Example: Retrieve a list of Pizzas and display them in a template

views.py

Pizzas = Pizza.objects.all()
return render_to_response( "pizza.html" , {'pizzas':Pizzas} )

pizza.html

{% for pizza in pizzas %}
    <li>pizza.name</li>
{% endfor %}

But, let’s say I want to add some arguments linked to the queryset but which are not in the database like something I computed in the view, I don’t know how to pass this argument to the template and how to use it -> EDIT : I want to order all my pizza by total calories in the template.

Example : For each Pizzas, I have computed the number of calories

views.py

Pizzas = Pizza.objects.all()
tab = []
for pizza in Pizzas:
    # Compute some data and return the total number of calories for one pizza
    total_number_calories = XXX
    tab.append({'p':pizza,'calories':total_number_calories'})        
return render_to_response( "pizza.html" , {'pizzas_calories':tab} )

pizza.html

?

I am not even sure my way to pass these additional data to the template is good (creating a table and pass it as an argument to the template.

If you have any idea or best practices to do that in Django I’ll take it (and lot of people using Django will do the same !)

Answer 1

You should always try and do as much as possible in the view. With the code you’ve shown, ordering by total calories is just one extra line after the for loop:

tab.sort(key=lambda t: t['calories'])