Django ListView: How can I create a conditional attribute that's accessible in my template?

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I am using ListView to list some objects from a model. I want to highlight entries in the displayed list where the listed item was created by the current user, and I plan to do this with a small coloured dot (circle) created using CSS. Here's a test case.

# models.py

from django.db import models
from django.contrib.auth.models import User

class Foo(models.Model):
    created_by = models.ForeignKey(
        User,
        to_field='username',
        on_delete=models.PROTECT,
        related_name='foos_as_usernames',
        blank=False
    )
    stuff = models.CharField(max_length=128, blank=True)

#views.py

from django.views.generic import ListView

class FooListView(ListView):
    model = Foo

    def get_context_data(self, **kwargs):
        context = super(FooListView, self).get_context_data(**kwargs)

        # Here I want to conditionally set a dot_class attribute based on
        # comparing Foo.created_by with the current user, i.e.
        # if object.created_by == user:
        #     object.dot_class = 'its-me'
        # What do I add here to create the dot_class attribute in the object_list?
        # Is there some other way I can pass a list to the foo_list.html template?

        return context


# foo_list.html

{% load static %}
<!DOCTYPE html>
<html>
<head>
    <title>FooBar</title>
    <style>
        .its-me { height: 8px; width: 8px; background-color: dodgerblue; border-radius: 50%; display: inline-block; }
    </style>
</head>
<body>
    <table>
        <tr>
            <th>&nbsp;</th>
            <th>Stuff</th>
        </tr>
        {% for obj in object_list %}
        <tr>
            <td><span class="{{ obj.dot_class }}"></span></td>
            <td>{{ obj.stuff }}</td>
        </tr>
        {% endfor %}
    </table>
</body>

For a bunch of reasons I need to do this in the CBV rather than annotate objects in the model.

How can I add an attribute to the objects in the context object_list? Alternatively, how can I pass a list to my template?

Thanks and regards...Paul

listview django
3 Answers

if you want to send as variable template then try this way:

def get_context_data(self, **kwargs):
    context = super(FooListView, self).get_context_data(**kwargs)
    foo_list = context['foo_list']
    for object in foo_list:
        if object.created_by == self.request.user:
            foo.dot_class = 'its-me'
            foo.save()
    context['foo_list'] = foo_list
    return context

then you can use it directly in template:

<td><span class="{{obj.dot_class}}"></span></td>
user_122617520

Perhaps you can use directly the authentication data that are already available in your template if you want to process specifically the objects that belong to the current connected user: cf django doc authentication-data-in-templates So your template will look like to something like this:

...
<body>
<table>
    <tr>
        <th>&nbsp;</th>
        <th>Stuff</th>
    </tr>
    {% for obj in object_list %}
    <tr>
        <td><span class={% if user.is_authenticated and obj.created_by == user%}"MY_FOO"{% else %}"OTHERS_FOO"{% endif%}></span></td>
        <td>{{ obj.stuff }}</td>
    </tr>
    {% endfor %}
</table>
....
</body>
user_61532280

@Pruthvi Barot's answer was a big help but not quite what I needed. What I realised is that you can't mess with the object_list and you can't iterate over the object_list and another list within the same code block. To overcome that, I create a completely new single list that combines the object_list data with the new data and iterate over that. Here's the code:

# models.py

from django.db import models
from django.contrib.auth.models import User

class Foo(models.Model):
    created_by = models.ForeignKey(
        User,
        to_field='username',
        on_delete=models.PROTECT,
        related_name='foos_as_usernames',
        blank=False
    )
    stuff = models.CharField(max_length=128, blank=True)


# views.py

from django.views.generic import ListView

class FooListView(ListView):
    model = Foo

    class NewFoo:
        def __init__(self, created_by, stuff, dot_class):
            self.created_by = created_by
            self.stuff = stuff
            self.dot_class = dot_class

    def get_context_data(self, **kwargs):
        context = super(FooListView, self).get_context_data(**kwargs)

        new_foo_list = []
        foo_list = context['foo_list']

        for foo in foo_list:
            dot_class = ''
            if foo.created_by == self.request.user:
                dot_class = 'its-me'

            new_foo = self.NewFoo(foo.created_by, foo.stuff, dot_class)
            new_foo_list.append(new_foo)

        context['new_foo_list'] = new_foo_list

        return context

# foo_list.html

{% load static %}
<!DOCTYPE html>
<html>
<head>
    <title>FooBar</title>
    <style>
        .its-me { height: 8px; width: 8px; background-color: dodgerblue; border-radius: 50%; display: inline-block; }
    </style>
</head>
<body>
    <table>
        <tr>
            <th>&nbsp;</th>
            <th>Stuff</th>
        </tr>
        {% for obj in new_foo_list %}
        <tr>
            <td><span class="{{ obj.dot_class }}"></span></td>
            <td>{{ obj.stuff }}</td>
        </tr>
        {% endfor %}
    </table>
</body>
user_54863640
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