Django field should not be shown in form but added by middleware at POST request-CodePudding

Let's say I've the following models:

from django.db import models

class TenantModelBase(models.Model):

    tenant = models.ForeignKey(to='accounts.TenantModel', on_delete=models.CASCADE)

    class Meta:
        abstract = True


class ModelFacade(models.Model):

    class Meta:
        abstract = True

    @entry_exit
    def save(self, force_insert=False, force_update=False, using=None, update_fields=None):
        return super().save(force_insert=force_insert, force_update=force_update, using=using, update_fields=update_fields)

    @entry_exit
    def get(self, *args, **kwargs):
        return super().objects.get(*args, **kwargs)

    @entry_exit
    def all(self):
        return super().objects.all()


class LocationModel(TenantModelBase, ModelFacade):

    city = models.CharField()
    country = models.CharField()
    building = models.CharField(blank=True)
    department = models.CharField(blank=True)
    contact_name = models.CharField(blank=True)
    email_address = models.EmailField(blank=True)
    phone_number = models.CharField(blank=True)

    class Meta(TenantModelBase.Meta):
        db_table = 'oam_locations'
        ordering = ['city']

The field "foo" should not be shown in the create form. Therefore the form is:

from django.forms import ModelForm

class LocationCreateForm(ModelForm):

    class Meta:
        model = LocationModel
        fields = ('city', 'country', 'building', 'department', 'contact_name', 'email_address', 'phone_number')

The field is NOT shown in the form. Excellent!

Now when POSTing the form, a middleware adds the 'TenantModelBase.tenant' field to the POST vars. The middleware looks like this:

    def __call__(self, request):
        if request.method == 'POST' and request.path not in ['/admin/login/']:
            user_profile = UserProfileModel.objects.get(user_id=request.user.id)
            _mutable = request.POST._mutable
            request.POST._mutable = True
            request.POST['tenant'] = str(user_profile.last_tenant_id)
            request.POST._mutable = _mutable

But when saving I get an "NOT NULL constraint failed: oam_locations.tenant_id" error. There seems to be some magic code aligning the POST vars (with "tenant" added by the middleware) to the form "fields" (w/o "tenant").

The stacktrace looks like this:

Environment:


Request Method: POST
Request URL: http://127.0.0.1:8000/oam/location/create

Django Version: 3.2.16
Python Version: 3.10.9
Installed Applications:
['django.contrib.admin',
 'django.contrib.auth',
 'django.contrib.contenttypes',
 'django.contrib.sessions',
 'django.contrib.messages',
 'django.contrib.staticfiles',
 'django.contrib.admindocs',
 'bootstrap5',
 'easyaudit',
 'main.apps.MainConfig',
 'accounts.apps.AccountsConfig',
 'oam.apps.OamConfig']
Installed Middleware:
['django.middleware.security.SecurityMiddleware',
 'django.contrib.sessions.middleware.SessionMiddleware',
 'django.middleware.locale.LocaleMiddleware',
 'django.middleware.common.CommonMiddleware',
 'django.middleware.csrf.CsrfViewMiddleware',
 'django.contrib.auth.middleware.AuthenticationMiddleware',
 'django.contrib.messages.middleware.MessageMiddleware',
 'django.middleware.clickjacking.XFrameOptionsMiddleware',
 'django.contrib.admindocs.middleware.XViewMiddleware',
 'easyaudit.middleware.easyaudit.EasyAuditMiddleware',
 'accounts.middleware.tenant_middleware.TenantMiddleware']



Traceback (most recent call last):
  File "C:\work\pro\vending\apollo\venv\lib\site-packages\django\db\backends\utils.py", line 84, in _execute
    return self.cursor.execute(sql, params)
  File "C:\work\pro\vending\apollo\venv\lib\site-packages\django\db\backends\sqlite3\base.py", line 423, in execute
    return Database.Cursor.execute(self, query, params)

The above exception (NOT NULL constraint failed: oam_locations.tenant_id) was the direct cause of the following exception:
  File "C:\work\pro\vending\apollo\venv\lib\site-packages\django\core\handlers\exception.py", line 47, in inner
    response = get_response(request)
  File "C:\work\pro\vending\apollo\venv\lib\site-packages\django\core\handlers\base.py", line 181, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "C:\work\pro\vending\apollo\venv\lib\site-packages\django\views\generic\base.py", line 70, in view
    return self.dispatch(request, *args, **kwargs)
  File "C:\work\pro\vending\apollo\venv\lib\site-packages\django\contrib\auth\mixins.py", line 71, in dispatch
    return super().dispatch(request, *args, **kwargs)
  File "C:\work\pro\vending\apollo\venv\lib\site-packages\django\views\generic\base.py", line 98, in dispatch
    return handler(request, *args, **kwargs)
  File "C:\work\pro\vending\apollo\venv\lib\site-packages\django\views\generic\edit.py", line 172, in post
    return super().post(request, *args, **kwargs)
  File "C:\work\pro\vending\apollo\venv\lib\site-packages\django\views\generic\edit.py", line 142, in post
    return self.form_valid(form)
  File "C:\work\pro\vending\apollo\venv\lib\site-packages\django\views\generic\edit.py", line 125, in form_valid
    self.object = form.save()
  File "C:\work\pro\vending\apollo\venv\lib\site-packages\django\forms\models.py", line 468, in save
    self.instance.save()
  File "C:\work\pro\vending\apollo\main\utils\decorators.py", line 22, in wrapper
    result = func(*args, **kwargs)
  File "C:\work\pro\vending\apollo\main\models\model_facade.py", line 15, in save
    return super().save(force_insert=force_insert, force_update=force_update, using=using, update_fields=update_fields)
  File "C:\work\pro\vending\apollo\venv\lib\site-packages\django\db\models\base.py", line 739, in save
    self.save_base(using=using, force_insert=force_insert,
  File "C:\work\pro\vending\apollo\venv\lib\site-packages\django\db\models\base.py", line 776, in save_base
    updated = self._save_table(
  File "C:\work\pro\vending\apollo\venv\lib\site-packages\django\db\models\base.py", line 881, in _save_table
    results = self._do_insert(cls._base_manager, using, fields, returning_fields, raw)
  File "C:\work\pro\vending\apollo\venv\lib\site-packages\django\db\models\base.py", line 919, in _do_insert
    return manager._insert(
  File "C:\work\pro\vending\apollo\venv\lib\site-packages\django\db\models\manager.py", line 85, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "C:\work\pro\vending\apollo\venv\lib\site-packages\django\db\models\query.py", line 1270, in _insert
    return query.get_compiler(using=using).execute_sql(returning_fields)
  File "C:\work\pro\vending\apollo\venv\lib\site-packages\django\db\models\sql\compiler.py", line 1416, in execute_sql
    cursor.execute(sql, params)
  File "C:\work\pro\vending\apollo\venv\lib\site-packages\django\db\backends\utils.py", line 98, in execute
    return super().execute(sql, params)
  File "C:\work\pro\vending\apollo\venv\lib\site-packages\django\db\backends\utils.py", line 66, in execute
    return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
  File "C:\work\pro\vending\apollo\venv\lib\site-packages\django\db\backends\utils.py", line 75, in _execute_with_wrappers
    return executor(sql, params, many, context)
  File "C:\work\pro\vending\apollo\venv\lib\site-packages\django\db\backends\utils.py", line 79, in _execute
    with self.db.wrap_database_errors:
  File "C:\work\pro\vending\apollo\venv\lib\site-packages\django\db\utils.py", line 90, in __exit__
    raise dj_exc_value.with_traceback(traceback) from exc_value
  File "C:\work\pro\vending\apollo\venv\lib\site-packages\django\db\backends\utils.py", line 84, in _execute
    return self.cursor.execute(sql, params)
  File "C:\work\pro\vending\apollo\venv\lib\site-packages\django\db\backends\sqlite3\base.py", line 423, in execute
    return Database.Cursor.execute(self, query, params)

Exception Type: IntegrityError at /oam/location/create
Exception Value: NOT NULL constraint failed: oam_locations.tenant_id

Any idea how to solve this?

CodePudding user response：

I think you need to add Meta class in Modelform

models.py

from django.db import models
class MyModel(models.Model):
    foo = models.CharField(max_length=120)
    bar = models.CharField(max_length=120)

form.py

from django.forms import ModelForm
class MyForm(ModelForm):
    class Meta:
        model = MyModel
        fields = ('bar',)

CodePudding user response：

You didn't specify whether the foo field can be null or not. I believe this is why it cannot create a MyModel object as it needs a foo value. Try adding null=True to your foo field.

Note: depending on what you want, you should consider looking whether blank=True is needed or not. Don't forget to migrate your changes to models.