How to mix two queries to one as dropdown elements - django

Question

I need to join and pass two queries of category and subcategory as elements of an autocomplete select2 dropdown as my django form field as below:
This is my form:
class CategoriesAutocomplete(autocomplete.Select2QuerySetView):
def get_queryset(self):
if not self.request.user.is_authenticated:
return Categories.objects.none()
qs = Categories.objects.all()
if self.q:
qs = qs.filter(Q(name__icontains=self.q))
return qs
def get_result_label(self, item):
return format_html( item.name)
class categories_form(forms.ModelForm):
categories = forms.ModelChoiceField(
queryset= Categories.objects.none(),
widget= autocomplete.ModelSelect2(
url='load_categories',
attrs={
'data-placeholder': 'Select a category',
'data-html': True,
'style': 'min-width: 15em !important;',
}
)
)
class Meta:
model = Post
fields = ['categories']
def __init__(self, *args, **kwargs):
super(category_form, self).__init__(*args, **kwargs)
self.fields['categories'].queryset = Categories.objects.all()
and in url:
path('ajax/categories-autocomplete', CategoriesAutocomplete.as_view(), name='load_categories'),
for category model:
class Categories(models.Model):
name = models.CharField(max_length=100)
brief = models.TextField(null=True)
slug = models.SlugField(max_length=200)
date = models.DateTimeField(default=timezone.now)
class Meta:
db_table = "categories"
for sub-category model:
class Sub_Categories(models.Model):
name = models.CharField(max_length=100)
brief = models.TextField(null=True)
slug = models.SlugField(max_length=200)
date = models.DateTimeField(default=timezone.now)
class Meta:
db_table = "sub_categories"
model to connect category with sub-categories:
class Categories_Sub_Categories(models.Model):
category = models.OneToOneField(Categories, primary_key=True, on_delete=models.CASCADE)
sub_cat = models.OneToOneField(Sub_Categories, on_delete=models.CASCADE)
class Meta:
db_table = "categories_sub-categories"
and in Post model:
class Post(models.Model):
title = models.CharField(max_length=50)
descript = HTMLField(blank=True, null=True)
categories = models.ForeignKey(Categories, blank=True, null=True, on_delete=models.CASCADE)
subcategories = models.ForeignKey(Sub_Categories, blank=True, null=True, on_delete=models.CASCADE)
author = models.ForeignKey(User, on_delete=models.CASCADE)
date = models.DateTimeField(default=timezone.now)
UPDATE:
The answer provided by #ha-neul is working just there is a bug. I show it with an example:
This is what expect in the dropdown:
**Asia**
China
Malaysia
India
Tajikistan
Iran
Qatar
**Europe**
Germany
Italy
Spain
Netherlands
France
**Africa**
Gana
...
But this is what I see:
**Asia**
China
Malaysia
**Europe**
Netherlands
France
Sweden
Norway
**Asia**
India
Tajikistan
Iran
**Europe**
Germany
Italy
**Asia**
Qatar
**Africa**
Gana
...
**America**
....
**Europe**
Spain
in the SubCategory table I have something like:
id ........... category_id
1 1
2 1
3 1
4 1
5 3
6 1
7 2
I am following this package. Any idea to make me even closer to the solution would be appreciated!!

Answer 1

If this is what you want to achieve, then:
The short answer is you should
have your subcategory with ForeignKeyField referring to
Category model.
use Select2GroupQuerySetView instead of Select2QuerySetView.
But implementing it is a bit complicated.
First of all, although django-autocomplete-light's source code has Select2GroupQuerySetView , somehow you cannot just use it as autocomplete.Select2GroupQuerySetView. So, you have to write the same thing in your own views.py. In addition, the source code has a typo, so you need to fix it.
Step 1. In models.py:
class Category(models.Model):
name = models.CharField(max_length=100)
brief = models.TextField(null=True)
slug = models.SlugField(max_length=200)
date = models.DateTimeField(default=timezone.now)
class SubCategory(models.Model):
##################
#You need add this line, so there is a one-to-many relationship
category = models.ForeignKey(Category, on_delete=models.CASCADE,
related_name='subcategories')
###############
name = models.CharField(max_length=100)
brief = models.TextField(null=True)
slug = models.SlugField(max_length=200)
date = models.DateTimeField(default=timezone.now)
Step2.in views.py copy-paste Select2GroupQuerySetView code and fix a typo
# import collections, so Select2GroupQuerySetView can work
import collections
class Select2GroupQuerySetView(autocomplete.Select2QuerySetView):
group_by_related = None
related_field_name = 'name'
def get_results(self, context):
if not self.group_by_related:
raise ImproperlyConfigured("Missing group_by_related.")
groups = collections.OrderedDict()
object_list = context['object_list']
print(object_list)
object_list = object_list.annotate(
group_name=F(f'{self.group_by_related}__{self.related_field_name}'))
for result in object_list:
group_name = getattr(result, 'group_name')
groups.setdefault(group_name, [])
groups[group_name].append(result)
return [{
'id': None,
'text': group,
'children': [{
'id': result.id,
'text': getattr(result, self.related_field_name),
# this is the line I had to comment out
#'title': result.descricao
} for result in results]
} for group, results in groups.items()]
3. write your own view using Select2GroupQuerySetView
class SubCategoryAutocomplete(Select2GroupQuerySetView):
print('under subcategory autocomplete')
group_by_related = 'category' # this is the fieldname of ForeignKey
related_field_name = 'name' # this is the fieldname that you want to show.
def get_queryset(self):
##### Here is what you normally put... I am showing the minimum code.
qs = SubCategory.objects.all()
if self.q:
qs = qs.filter(name__istartswith=self.q)
return qs
Howe to use this view in a your project?
1. Say you have a Post model as below, with subcategory as a ForeignKey.
class Post(models.Model):
title = models.CharField(max_length=100)
subcategory = models.ForeignKey(SubCategory,on_delete=models.CASCADE)
def __str__(self):
return self.title
2. You will generate a PostForm that contains the subcategory autocomplete field.
in forms.py
from django.conf.urls import url
class PostForm(forms.ModelForm):
subcategory = forms.ModelChoiceField(
queryset=Subcategory.objects.all(),
widget=autocomplete.ModelSelect2(url='subcategory-autocomplete')
)
class Meta:
model= Post
fields = ('title','subcategory')
You will generate a CreatePostView using generic CreateView
from django.views.generic.edit import CreateView
class CreatePostView(CreateView):
model=Post
template_name='yourapp/yourtemplate.html'# need to change
form_class=PostForm
success_url = '/'
Now, in your urls.py, one url for CreatePostView another one for autocomplete view.
urlpatterns = [
url(
r'^subcategory-autocomplete/$',
SubCategoryAutocomplete.as_view(),
name='subcategory-autocomplete',
),
path('post/create',CreatePostView.as_view(), name='create_post'),
it's all set, you will go to post/create and see a PostForm with subcategories autocomplete field.
OP had a weird grouping behavior after using the code above. In his comment, he mentioned:
Added a .order_by(category_id')` to the qs and fixed it.

Answer 2

You do not need to create this model to make a relation
Categories_Sub_Categories
just create a one-to-many field (categories) in Sub_Categories model and put Categories model there (foreign), it will do that automatically, then retrieve data like this (in backend)
categories = Categories.objects.all()
you will get all categories with Sub_Categories object here, pass it to frontend and loop through it (in front-end)
for category in categories:
sub_categories = category.sub_categories_set.all()

Answer 3

To make SubCategory you can have ForeignKey to self.
Another point, you'll need to use prefetch_related from main model (Post) to be able to "join" Category/SubCategory there.
Here is an example how this should look like:
# forms.py
from django import forms
from django.db.models import Prefetch
class PostForm(forms.ModelForm):
class Meta:
model = Post
fields = [...]
def __init__(self, *args, **kwargs):
super(PostForm, self).__init__(*args, **kwargs)
cats = Category.objects \
.filter(category__isnull=True) \
.order_by('order') \
.prefetch_related(Prefetch('subcategories',
queryset=Category.objects.order_by('order')))
self.fields['subcategory'].choices = \
[("", self.fields['subcategory'].empty_label)] \
+ [(c.name, [
(self.fields['subcategory'].prepare_value(sc),
self.fields['subcategory'].label_from_instance(sc))
for sc in c.subcategories.all()
]) for c in cats]
# models.py
class Category(models.Model):
category = models.ForeignKey('self', null=True, on_delete=models.CASCADE,
related_name='subcategories', related_query_name='subcategory')
class Post(models.Model):
subcategory = models.ForeignKey(Category, on_delete=models.CASCADE,
related_name='posts', related_query_name='post')