Querying Many to many fields in django template

问题

This may not be relevant but just wanted to ask,

IF an object is passed from views to template and in the template will i be able to query many to many fields

Models code:

  class Info(models.Model):
     xls_answer  = models.TextField(null=True,blank=True)


  class Upload(models.Model):
     access = models.IntegerField()
     info = models.ManyToManyField(Info)
     time = models.CharField(max_length=8, null=True,blank=True)
     error_flag = models.IntegerField()

     def __unicode__(self):
        return self.access

Views:

         // obj_Arr  contains all the objects of upload
        for objs in obj_Arr:
           logging.debug(objs.access)
           logging.debug(objs.time)


        return render_to_response('upload/new_index.html', {'obj_arr': obj_Arr , 'load_flag' : 2})

In template is it possible to decode the many to many field since we are passing the object

Thanks..

回答1:

In general, you can follow anything that's an attribute or a method call with no arguments through pathing in the django template system.

For the view code above, something like

{% for objs in obj_arr %}
{% for answer in objs.answers.all %}
  {{ answer.someattribute }}
{% endfor %}
{% endfor %}

should do what you're expecting.

(I couldn't quite make out the specifics from your code sample, but hopefully this will illuminate what you can get into through the templates)

回答2:

It's also possible to register a filter like this:

models.py

class Profile(models.Model):
    options=models.ManyToManyField('Option', editable=False)

extra_tags.py

@register.filter
def does_profile_have_option(profile, option_id):
    """Returns non zero value if a profile has the option.
    Usage::

        {% if user.profile|does_profile_have_option:option.id %}
        ...
        {% endif %}
    """
    return profile.options.filter(id=option_id).count()

More info on filters can be found here https://docs.djangoproject.com/en/dev/howto/custom-template-tags/

来源：https://stackoverflow.com/questions/3411961/querying-many-to-many-fields-in-django-template