Nested Collections with relatedModel - example

[gumish]

Hello,
at first I would like to thank you for the awesome work. The formsets in vanilla Django have been always disaster for me.

Could you please write me some example how to use Nested Collection with related Model (for example 3 levels)?

When I write it due to examples here ..
https://django-formset.readthedocs.io/en/latest/collections.html#nested-collection
https://django-formset.readthedocs.io/en/latest/model-collections.html#
.. it works only with the top level. But not with lower levels.
I have not found any example also here..
https://github.com/jrief/django-formset/tree/main/testapp/forms

I am not sure about the sentence:

Since form collections can be nested, method model_to_dict can be used to recursively create a dictionary to initialize the forms, starting from a main model object.

The model_to_dict() in the 2nd level is not even started.

class MemberCollection(FormCollection):
    ''' 2nd level - This level DOES NOT work - there are no initial member-forms
    '''
    min_siblings = 0
    member = MemberForm()

    def model_to_dict(self, team):
        fields = self.declared_holders['member']._meta.fields
        return [{'member': model_to_dict(member, fields=fields)}
                for member in team.members.all()]

    def construct_instance(self, team, cleaned_data):
        for data in cleaned_data:
            try:
                member = team.members.get(id=data['member']['id'])
            except (KeyError, Member.DoesNotExist):
                member = Member(team=team)
            form_class = self.declared_holders['member'].__class__
            form = form_class(data=data['member'], instance=member)
            if form.is_valid():
                if form.marked_for_removal:
                    member.delete()
                else:
                    construct_instance(form, member)
                    form.save()

class TeamCollection(FormCollection):
    """ 1st level - This level works - saved objects are rendered
    """
    min_siblings = 0
    team = TeamForm()
    members = MemberCollection()

    def model_to_dict(self, company):
        fields = self.declared_holders['team']._meta.fields
        return  [{'team': model_to_dict(team, fields=fields)}
            for team in company.teams.all()]

    def construct_instance(self, company, cleaned_data):
        for data in cleaned_data:
            try:
                team = company.teams.get(id=data['team']['id'])
            except (KeyError, Team.DoesNotExist):
                team = Team(company=company)
            form_class = self.declared_holders['team'].__class__
            form = form_class(data=data['team'], instance=team)
            if form.is_valid():
                if form.marked_for_removal:
                    team.delete()
                else:
                    construct_instance(form, team)
                    form.save()


class CompanyCollection(FormCollection):
    """ 0 level - Main edited object
    """
    form = CompanyForm()
    teams = TeamCollection()

Simple FormModels:

class CompanyForm(forms.ModelForm):
    class Meta:
        model = Company
        fields = '__all__'

class TeamForm(forms.ModelForm):
    id = forms.IntegerField(required=False, widget=forms.HiddenInput)
    class Meta:
        model = Team
        fields = ('id', 'name',)

class MemberForm(forms.ModelForm):
    id = forms.IntegerField(required=False, widget=forms.HiddenInput)
    class Meta:
        model = Member
        fields = ('id', 'name')

[jrief]

Thanks for these forms. I will add them to the unit tests, asap.

Please note, that yesterday I found a bug on the client side, when aggregating data on a root collection with siblings. This has been fixed in version 0.13.3.

[gumish]

I have tried the new version 0.13.3 but it doesn't solve my issue.

[gumish]

So I would very appreciate if you could write me some short working example.

[jrief]

I will use your models and create a nested form collection using them as a starting point. Please give me some time for this setup, since I'm not working full time on django-formset.

[jrief]

Just wanted to start implementing your form collections.

Could you please also paste the models Company, Team and Member you are using.

[gumish]

Sure. They are only models for testing so they are simple as possible.

class Company(models.Model):
    name = models.CharField('Company Name', max_length=50)

    class Meta:
        verbose_name = 'Company'
        verbose_name_plural = 'Companies'

    def __str__(self):
        return self.name

class Team(models.Model):
    name = models.CharField('Team Name', max_length=50)
    company = models.ForeignKey(Company, on_delete=models.CASCADE, related_name='teams')

    class Meta:
        verbose_name = 'Team'
        verbose_name_plural = 'Teams'

    def __str__(self):
        return self.name

class Member(models.Model):
    name = models.CharField('Member Name', max_length=50)
    team = models.ForeignKey(Team, on_delete=models.CASCADE, related_name='members')

    class Meta:
        verbose_name = 'Member'
        verbose_name_plural = 'Members'

    def __str__(self):
        return self.name

[jrief]

You have a bug in class TeamCollection. Method model_to_dict should look like:

class TeamCollection(FormCollection):
    …
    def model_to_dict(self, company):
        data = []
        fields = self.declared_holders['team']._meta.fields
        for team in company.teams.all():
            data.append({
                'team': model_to_dict(team, fields=fields),
                'members': self.declared_holders['members'].model_to_dict(team),
            })
        return data
    …

[gumish]

Awesome - thanxks! It looks logic and simple. It hasn't been clear for me from the documentation.
Could you please also write here the "def construct_instance" part of the TeamCollection?
I could make up something but I would like to see the clean solution from author :)

[jrief]

I will add a special CRUD section to nested form collections.

FYI: In the next major version, I'm going to change the signature of construct_instance. Instead of having to pass the cleaned_data created by form_collection.full_clean() I will add a dict/list of valid_holders to each collection. These entities then contain the cleaned_data in an unnested structure.

[jrief]

@gumish I just added two extra views, they are named companyand companies.
The first one can be used to edit one company and it stores level 1 Team and level 2 Member.

The latter one can be used to edit multiple companies at once.

Please note that you have to check out branch https://github.com/jrief/django-formset/tree/issue_37 in order to test this.