Django1.4: How to use order_by in template?

Question

Django1.4: How to use order_by in template?

models.py

from django.db import models
from django.contrib.auth.models import User
from django.contrib.contenttypes.models import ContentType
from django.contrib.contenttypes import generic

class Note(models.Model):
    contents = models.TextField()
    writer = models.ForeignKey(User, to_field='username')
    date = models.DateTimeField(auto_now_add=True)

    content_type = models.ForeignKey(ContentType)
    object_id = models.PositiveIntegerField()
    content_object = generic.GenericForeignKey('content_type', 'object_id')


class Customer(models.Model):
    name = models.CharField(max_length=50,)
    notes = generic.GenericRelation(Note, null=True)

Above is my models.py.

I want to use 'order_by'(https://docs.djangoproject.com/en/dev/ref/models/querysets/#order-by)

And...

views.py

from django.views.generic import DetailView
from crm.models import *

class customerDetailView(DetailView):
    context_object_name = 'customerDetail'
    template_name = "customerDetail.html"
    allow_empty = True
    model = Customer
    slug_field = 'name'

My views.py use DetailView(https://docs.djangoproject.com/en/1.4/ref/class-based-views/#detailview).

And

customerDetail.html

<table class="table table-bordered" style="width: 100%;">
    <tr>
        <td>Note</td>
    </tr>
    {% for i in customerDetail.notes.all.order_by %}<!-- It's not working -->
        <tr>
            <th>({{ i.date }}) {{ i.contents }}[{{ i.writer }}]</th>
        </tr>
    {% endfor %}
</table>

I want to use order_by in template...

What should I do?

Solution 1

The order_by needs at least one argument, and Django does not allow you to pass arguments to a function or method inside a template.

Some alternatives are:

• Use Jinja2 template engine instead of Django's one (Jinja2 will let you pass arguments to methods and is said to perform better)
• order the dataset in the view
• use the "Meta:ordering" attribute to define a default ordering criteria for your models
• write a custom filter so you can queryset|order_by:'somefield' (see this snippet)
• as suggested by Michal, you can write a custom Manager with predefined methods for the orderings you need

Solution 2

Check out the dictsort filter, it's pretty much what you're looking for I think.

Comments

[rxdazn]

have you tried queryset = Customer.objects.order_by() in customerDetailView?

[chobo]

Yeah, I tried queryset = Customer.objects.order_by('note__date') and queryset = Customer.objects.order_by('note__date'). But failed...

[Michal Čihař]

...or use custom Manager for the class which will provide you predefined ways of ordering

[chobo]

I don't know understand fourth tip "write a custom filter so you can queryset|order_by:'somefield'". Could you give me ... some example code?

[chobo]

Anyway I solved it. class Meta: ordering = ['date'] (in models.py)

[Paulo Scardine]

cathy answer has such sample code, seems like she is using the same snippet (but she forgot to attribute the solution to the original author). Also, you need to place this file in some specific location in order to be able to load it inside the template.

[Corentin S.]

This is the easiest answer and it does work on querysets.

[Muhammad Zubair]

@chobo regarding the fourth tip, you may use the link he has provided or refer to this link. pluralsight.com/guides/… . The fourth tip worked for me