Django ManyToMany Template Rendering and Performance Features

Question

I have a django model that contains a multi-valued relation, such as,

class MyModel(models.Model):
  name = ..
  refby = models.ManyToManyField(MyModel2)
  ..

class MyModel2(..):
  name = ..
  date = ..

I need to display it in my template so that I can display all mymodel2 objects that reference mymodel. I am currently doing something like the following,

{% for i in mymodel_obj_list %}
  {{i.name}}
  {% for m in i.refby.all|dictsortreversed:"date"|slice:"3" %}
    {{.. }}
  {% endfor %}
  <div> <!--This div toggles hidden/visible, shows next 12-->
   {% for n in i.refby.all|dictsortreversed:"date"|slice:"3:15" %}
     {{.. }}
   {% endfor %}
  </div>
{% endfor %}

As the code shows, I want to show only the last 3 objects of mymodel2, sorted in reverse order by date, although the next 12 are loaded.

Is this a very inefficient method? (Given that the results for refby.all can be several 100 seconds, and the total number of results in "mymodel_obj_list" is also 100 seconds - I use paginator there).

, refb ? , ? , , .

:

obj_list = Table.objects.filter(..) # Few 100 records
pl = CustomPaginatorClass(obj_list...)

pl mymodel_obj_list.

!

Answer 1

, mymodel_obj_list - QuerySet. , , Django refby , . , .

select_related QuerySet, .

https://docs.djangoproject.com/en/dev/ref/models/querysets/#select-related

Answer 2

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