Generating a minimal ModelForm to add a value to a ManyToManyField on self using the related name

Using Django Forms & APIs
1

Hello,

I’ve been baffled by the behaviour of following code snippet (stripped down version of real code)

from django.db import models
from django import forms

class Employee(models.Model):
  id = models.BigAutoField(primary_key=True)
  name = models.CharField(max_length=32)
  managers = models.ManyToManyField(
        'self',
        blank=True,
        related_name='managed_employees',
        symmetrical=False,
    )
  class Meta:
    app_label = 'Minimal Test'

def generate_minimal_form(field):
  class UpdateManagerForm(forms.ModelForm):
    class Meta:
      model = Employee
      fields=[field]

for field_name in ["managers", "managed_employees"]:
  try:
    generate_minimal_form(field_name)
  except Exception as e:
    print(f'Could not generate minimal form for {field_name} : {e}')

It outputs

Could not generate minimal form for managed_employees : Unknown field(s) (managed_employees) specified for Employee

But on any instance of Employee,

 instance._meta.get_field('managed_employees')

Suceeds.

I’ve tracked this to the fact that managed_employeesdoes not appear in

forms.models.fields_for_model(Employee)

as it does not appear in Employee._meta.many_to_many

It seems this is because models.options.Option.add_field does not handle many_to_many fields to self, but I’m unsure as whether it should.

The high level use case is an attempt at writting a generic inline edit, where when displaying the data related to an Employee, any field can be edited in place using htmx : on a click, a form limited to the update of the current value appears. This form is limited to a select button for ManyToMany relations so as to be able to simply add new values. I might have gone to far in a bad direction before hitting this issue.

Any other ideas on how to generate a form to add a ’managed_employee’ in this use-case ?