Problem with ManyToManyField in other model's forms using Bootstrap

Question

I would like to show possible choices from ManyToManyField (which I have in Homes model) in the Owners form. I have Owners <--Many2Many--> Homes with custom class HomesOwners. In Homes it works out of the box, I don't know how to make it work in Owners.

I am using Django 2.2.4 with Bootstrap 4 and Postgresql. I started my project based on django-bookshelf project (also just Django and Bootstrap4). I do not use any render. Comment in django-bookshelf project mentioned How to add bootstrap class to Django CreateView form fields in the template?, so I stick to that if it comed to forms.

I'm pretty new to Python (so Django too) and web technologies in general. I googled dozen of different questions/answers but I couldn't find any nice explanation of what is what and how to use it in real life. Most of them ended up with basic usage.

I did some experimentation on my own, but no success so far...

Here is the code

I have two models - Homes/models.py and Owners/models.py

Homes/models.py:

class Homes(models.Model):
   id = models.AutoField(primary_key=True)
   # other fields
   some_owners = models.ManyToManyField(Owners, through='HomesOwners', through_fields=('id_home', 'id_owner'), related_name='some_owners')
   # end of fields, some other code in the class like "class Meta" etc.

class HomesOwners(models.Model):
   id = models.AutoField(primary_key=True)
   id_home = models.ForeignKey(Homes, models.DO_NOTHING, db_column='id_home')
   id_owner = models.ForeignKey('owners.Owners', models.DO_NOTHING, db_column='id_owner')

Owners/models.py do not have anything special, no imports from my Homes/models.py etc.

and my forms:

Homes/forms.py:

class HomesForm(forms.ModelForm):
   def __init__(self, *args, **kwargs):
      super(HomesForm, self).__init__(*args, **kwargs)
      self.fields['some_field_from_homes_model'].widget.attrs = {'class': 'form-control '}
      #
      # --> no need self.fields for M2M, Django does the work
      #
      # but I tried also and have a --> Question 2
      # self.fields["some_owners"].widget = forms.widgets.CheckboxSelectMultiple()
      # self.fields["some_owners"].queryset = HomesOwners.objects.all()

Without any code as "self.fields" for M2M field, Django is able to generate for me list of owners.

Question 1

I would like to get list of Homes in my OwnersForms.

I do not know what to add. I assume that I cannot add

# Owners/models.py
some_homes = models.ManyToManyField(Homes, through='HomesOwners', through_fields=('id_home', 'id_owner'), related_name='some_homes')

because of circular import, am I right?

How do I get my Homes list using self.fields? What do I need to add to my code?

Question 2

When I've added

# Homes/forms.py
self.fields["some_owners"].widget = forms.widgets.CheckboxSelectMultiple()
self.fields["some_owners"].queryset = HomesOwners.objects.all()

I got

<!-- html page -->
HomesOwners object (1)
HomesOwners object (2)
<!-- and so on... -->

How can I just list Owners? How to filter/order them so first they would appear Owners not connected to any Home?

Question 3

class HomesOwners(models.Model):
   id = models.AutoField(primary_key=True)
   id_home = models.ForeignKey(Homes, models.DO_NOTHING, db_column='id_home')
   id_owner = models.ForeignKey('owners.Owners', models.DO_NOTHING, db_column='id_owner')

def __str__(self):
   return pass #return something

I can't get my head around this. This class connects Homes and Owners. When I'm thinking of Homes I would like to return Owners and vice versa. So it should return different things depending on what object we are using (home or owner). I think this is connected to my 2nd question about:

HomesOwners object (1)

Also...

In homes.html I'm using my M2M like that:

{% for owner in homes.homesowners_set.all %}
{{ owner.id_owner.id }}
{% endfor %}

I would like to write something similar to my owners.html and list homes. This is connected to my previous question, I would like to have full answer if that's possible.

EDIT

With the answer given to me I was able to add Homes to OwnerUpdate view. I have views like that: owners/views.py

# List View
class OwnersList(ListView):
    model = Owners

# Detail View
class OwnersView(DetailView):
    model = Owners

# Create View
class OwnersCreate(CreateView):
    model = Owners
    form_class = OwnersForm
    # Setting returning URL
    success_url = reverse_lazy('owners_list')

# Update View
class OwnersUpdate(UpdateView):
    model = Owners
    form_class = OwnersForm
    success_url = reverse_lazy('owners_list')

# Delete View
class OwnersDelete(DeleteView):
    model = Owners
    success_url = reverse_lazy('owners_list')

What change do I need to make to be able to show in OwnersList Homes they own? In Homes DetailView I am able to show Owners. I would like to do the same for Homes' DetailView and Homes ListView.

Answer 1

I don't really get it what you asking for,
but if I understand your question correctly,
I assume you want to add Homes list (not HomesOwners list) into your Owners form, right?

you can add extra field in your form like this:

class OwnersForm(ModelForm):
    # notice the queryset is 'Homes' not 'HomesOwners'
    homes = forms.ModelMultipleChoiceField(queryset=Homes.objects.all(), widget=forms.CheckboxSelectMultiple)

    class Meta:
        model = Owners
        fields = ('homes', 'your_other_fields',)

    # then you can access in init function too if you want
    def __init__(self, *args, **kwargs):
        super(OwnersForm, self).__init__(*args, **kwargs)
        self.fields['homes'].required = False

then, since it using CheckboxSelectMultiple widget, you can iterate it in your html template like this:

{% for key, value in your_form.homes.field.choices %} <!-- notice '.field.'-->
{{ key }} = {{ value }}
{% endfor %}

you probably need to create custom save too for your form.

---

for your question 3, it is not about the form?
If you want to show HomesOwners, you are already doing right.

{% for owner in homes.homesowners_set.all %}
{{ owner.id_owner.id }}
{% endfor %}

but it will work if that homes is only 1 object.
if homes is a queryset, you have to iterate it first

{% for home in homes %}
    {% for owner in home.homesowners_set.all %}
    {{ owner.id_owner.id }}
    {% endfor %}
{% endfor %}

sorry if I misunderstanding your questions,
maybe you can provide your views.py too, so I or others can help you more specific