Django Reverse Query in Template

Question

I have models like this

class Blog(models.Model):
    name = models.CharField(max_length=100)
    tagline = models.TextField()

    def __unicode__(self):
        return self.name

class Entry(models.Model):
    blog = models.ForeignKey(Blog)
    headline = models.CharField(max_length=255)

I want to list all blogs in a page. I have written a view such that

def listAllBlogs(request):
    blogs= Blog.objects.all()
    return object_list(
        request,
        blogs,
        template_object_name = "blog",
        allow_empty = True,
        )

And I can display tagline of blog such that in view

{% extends "base.html" %}
{% block title %}{% endblock %}
{% block extrahead %}

{% endblock %}

{% block content %}
     {% for blog in blog_list %}
          {{ blog.tagline }}
     {% endfor %}
{% endblock %}

But I would like to show, such thing blog__entry__name but I don't know how can I achive this in template. Also, there may be no entry in a blog. How can I detect in template ?

Thanks

Both answers below are correct, just two remarks. Define `related_name='entries'` for `blog` field, and you will be able to write `blog.entries`. And use `select_related()`, not to make N + 1 SQL queries. — DrTyrsa, Jun 10 '11 at 13:02

score 41 · Accepted Answer · answered Jun 10 '11 at 12:59

41

To access blog entries (Related Manager): blog.entry_set.all

To do other actions if blog have no entries, you have the {% empty %} tag that is executed when the set is empty.

{% block content %}
     {% for blog in blog_list %}
          {{ blog.tagline }}
          {% for entry in blog.entry_set.all %}
              {{entry.name}}
          {% empty %}
             <!-- no entries -->
          {% endfor %}
     {% endfor %}
{% endblock %}

answered Jun 10 '11 at 12:59

manji

47,442
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@brsbilgic [related_name](https://docs.djangoproject.com/en/dev/ref/models/fields/#django.db.models.ForeignKey.related_name) – DrTyrsa Jun 10 '11 at 13:20
For a `OneToOneField` you can simply use: `blog.entry` (instead of `blog.entry_set`). https://docs.djangoproject.com/en/dev/topics/db/queries/#one-to-one-relationships – manji Jun 10 '11 at 13:27
That works great. Thank you! But what if the relationship were one-to-one blog = models.OneToOneField(Blog,unique=True) . What is the right way to do such thing in template like ` {{ blog.entry__headline }}` – brsbilgic Jun 10 '11 at 13:28

score 9 · Answer 2 · answered Jun 10 '11 at 12:55

9

based on your code you could do the following.

{% block content %}
     {% for blog in blog_list %}
          {{ blog.tagline }}
          {% for entry in blog.entry_set.all %}
              {{entry.name}}
          {% endfor %}
     {% endfor %}
{% endblock %}

answered Jun 10 '11 at 12:55

JamesO

25,178
4
40
42

Shouldn't that be blog.entry_set rather than blog_entry_set? – bcoughlan Jun 10 '11 at 12:57

Django Reverse Query in Template

2 Answers2

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