Q:
Django template tag to display objects from model
I'm trying to pass two different instances of the same model into a template using a django template tag. I tried to follow the example for passing an instance of a model into the template as shown here:
Django template Tag: How to display related object list in template?
{% for a in object.articles.all %}
{{ a }}
{% endfor %}
However I would like to go another level in depth and be able to show the related objects for this model too. I have searched through the internet and found multiple ways of doing this, but it is just not working for me.
models.py:
class Event (models.Model):
name = models.CharField(max_length=256)
venue = models.CharField(max_length=256)
venue_event_id = models.IntegerField(unique=True, null=True, blank=True)
venue_location_name = models.CharField(max_length=256)
venue_location_address = models.CharField(max_length=256)
venue_location_phone = models.CharField(max_length=256)
venue_location_street = models.CharField(max_length=256)
venue_location_postalcode = models.CharField(max_length=256)
venue_event_location_name = models.CharField(max_length=256)
venue_event_location_address = models.CharField(max_length=256)
venue_event_location_phone = models.CharField(max_length=256)
venue_event_location_street = models.CharField(max_length=256)
venue_event_location_postalcode = models.CharField(max_length=256)
related_venues = models.ManyToManyField(Venue)
related_events = models.ManyToManyField(Event)
def __unicode__(self):
return self.name
class Venue (models.Model):
name = models.CharField(max_length=256)
address = models.CharField(max_length=256)
city = models.CharField(max_length=256)
state = models.CharField(max_length=256)
postalcode = models.CharField(max_length=256)
phone = models.CharField(max_length=256)
street = models.CharField(max_length=256)
distance = models.FloatField()
image_url = models.CharField(max_length=256)
latitude = models.FloatField()
longitude = models.FloatField()
objects = VenueQuerySet.as_manager()
def __unicode__(self):
return self.name
def get_absolute_url(self):
return "/venue/%s/" % self.slug
class EventLocation (models.Model):
name = models.CharField(max_length=256)
address = models.CharField(max_length=256)
city = models.CharField(max_length=256)
state = models.CharField(max_length=256)
postalcode = models.CharField(max_length=256)
phone = models.CharField(max_length=256)
street = models.CharField(max_length=256)
distance = models.FloatField()
image_url = models.CharField(max_length=256)
latitude = models.FloatField()
longitude = models.FloatField()
objects = EventLocationQuerySet.as_manager()
def __unicode__(self):
return self.name
class VenueLocation(models.Model):
event = models.ForeignKey(Event, related_name='events')
venue = models.ForeignKey(Venue, related_name='venues')
name = models.CharField(max_length=256)
address = models.CharField(max_length=256)
city = models.CharField(max_length=256)
state = models.CharField(max_length=256)
postalcode = models.CharField(max_length=256)
phone = models.CharField(max_length=256)
street = models.CharField(max_length=256)
distance = models.FloatField()
image_url = models.CharField(max_length=256)
latitude = models.FloatField()
longitude = models.FloatField()
objects = VenueLocationQuerySet.as_manager()
def __unicode__(self):
return self.name
class EventQuerySet (models.Model):
slug = models.SlugField(max_length=256)
name = models.CharField(max_length=256)
events_description = models.CharField(max_length=256)
events_dates = models.CharField(max_length=256)
objects = EventQuerySetQuerySet.as_manager()
def __unicode__(self):
return self.name
template.py:
from django.template import Template, Context
from django.template.loader import get_template
from .models import *
register = template.Library()
@register.simple_tag(takes_context=True)
def events_for_instance(context):
instance = context.get('object')
template = get_template('_events_by_instance.html')
html = template.render(Context({'instance': instance}))
return html
html:
{% load events_by_instance %}
{% for a in instance.related_venues.all %}
-
{{ instance.venue_location_name }}
{{ a.venue_location_address }}
{% endfor %}
================================================
{% for a in instance.related_events.all %}
{{ instance.venue_location_name }}
{{ a.venue_location_address }}
{% endfor %}
How can I display all related object instances in a django template?
A:
Your issue is the related_name argument to the ForeignKey. By default django uses the related name as a reverse lookup when you specify a related_name argument.
https://docs.djangoproject.com/en/dev/topics/db/queries/#related-object-lookups
In case you specify a string as a related_name argument, the relation between the two models is done with a dictionary-like structure where the model name is the key, and the reverse relation is stored in the value. This means that it is possible to have two models that share the same name in the models.py, but still have unique related names:
class Car(models.Model):
manufacturer = models.CharField(max_length=255, unique=True)
models = models.ManyToManyField('self', symmetrical=False,
related_name="cars_created", db_index=True)
class License(models.Model):
car = models.ForeignKey(Car, related_name="cars_on_hold")
plates = models.ManyToManyField(LicensePlate, related_name="cars_held")
In your case:
class Event (models.Model):
name = models.CharField(max_length=256)
venue = models.CharField(max_length=256)
venue_event_id = models.IntegerField(unique=True, null=True, blank=True)
venue_location_name = models.CharField(max_length=256)
venue_location_address = models.CharField(max_length=256)
venue_location_phone = models.CharField(max_length=256)
venue_location_street = models.CharField(max_length=256)
venue_location_postalcode = models.CharField(max_length=256)
related_venues = models.ManyToManyField(Venue, related_name='events')
def __unicode__(self):
return self.
