How can I enter a record to a model when an attribute to fill is a foreign key? -IntegrityError

I have the following structure of my project:

I wanted to state the entire business context of my application (at least the one that pertains to the problem I have) to better illustrate the situation. Apologies in advance for the length of the post, that's why.

Two applications called userprofile and rbsessions

project
    userprofile
        models.py
    rbsessions
        models.py

In userprofile/models.py I am managing the user schema through the following models: User, MedicalProfile, PatientProfileand TherapistProfile. Which means that in my system there are users who are doctors, who are patients and who are therapists.

When I create a user via django admin, I must associate one of these attributes:

• is_medical: It will be a medical user and if I select it when creating it, a profile of that user will be automatically created in the MedicalProfile model

• is_patient: It will be a patient user and if I select it when creating it, a profile of that user will be automatically created in the PatientProfile model

• is_therapist: It will be a therapist user and if I select it when creating it, a profile of that user will be automatically created in the TherapistProfile model

It is understood that when a patient user is created in the system, it is because he is going to receive therapy sessions or medical appointments. (I will detail the data of a therapy session later in a class called Session)

When a patient user is created, I want PatientProfilean instance of the class to be automatically created in addition to his profile (which is already created) Session(I will detail it later) which will mean that he will have an appointment assigned.

( see last condition elif in the User model that I will present below )

According to the above, the models User, MedicalProfile, PatientProfile, TherapistProfileare the following:

• Usermodel( userprofile/models.py)

  from __future__ import unicode_literals
  from django.conf import settings
  from django.utils import timezone
  from datetime import datetime
  from django.contrib.auth.models import AbstractUser
  from django.db import models 
  from django.dispatch import receiver
  from django.db.models.signals import post_save
  from rbsessions.models import Session
  
  class User(AbstractUser):
  
      birth_date = models.DateTimeField(default=timezone.now())
  
      address = models.CharField(max_length=150, blank=False)
  
      phone = models.CharField(verbose_name=u'phone', max_length=25, blank=True)
  
      is_medical = models.BooleanField(default=False)
  
      is_therapist = models.BooleanField(default=False)
  
      is_patient = models.BooleanField(default=False)
  
      slug = models.SlugField(max_length=100, blank=True)
  
      photo = models.ImageField(upload_to='avatars', blank = False)
  
  #Sobreescribo el metodo save para la creacion de cada perfil de usuario
      def save(self, *args, **kwargs):
         user = super(User, self).save( *args, **kwargs)
  
          # Creating and user with medical, patient and therapist profiles
          if self.is_medical and not MedicalProfile.objects.filter(user=self).exists()\
              and self.is_patient and not PatientProfile.objects.filter(user=self).exists()\
              and self.is_therapist and not TherapistProfile.objects.filter(user=self).exists():
  
              medical_profile=MedicalProfile(user=self).save()
              patient_profile=PatientProfile(user=self).save()
              therapist_profile=TherapistProfile(user=self).save()
  
  
          # Creating and user with medical and patient profiles
          elif self.is_medical and not MedicalProfile.objects.filter(user=self).exists()\
          and self.is_patient and not PatientProfile.objects.filter(user=self).exists():
  
              medical_profile=MedicalProfile(user=self).save()
              patient_profile=PatientProfile(user=self).save()
  
          # Creating and user with medical and therapist profiles
          elif self.is_medical and not MedicalProfile.objects.filter(user=self).exists()\
          and self.is_therapist and not TherapistProfile.objects.filter(user=self).exists():
  
              medical_profile=MedicalProfile(user=self).save()
              therapist_profile=TherapistProfile(user=self).save()
  
          # Creating and user with physiotherapist and patient profiles
          elif self.is_therapist and not TherapistProfile.objects.filter(user=self).exists()\
          and self.is_patient and not PatientProfile.objects.filter(user=self).exists():
  
              therapist_profile = TherapistProfile(user=self).save()
              patient_profile = PatientProfile(user=self).save()
  
          # Creating and user with medical profile
          elif self.is_medical and not MedicalProfile.objects.filter(user=self).exists():
              profile = MedicalProfile(user=self)
              profile.save()
  
          # Creating and user with patient profile ---Here---
          elif self.is_patient and not PatientProfile.objects.filter(user=self).exists():
              profile = PatientProfile(user=self)
              profile.save()
  
          #Quiero crear una instancia de una sesión de rehabilitacion para cuando se crea un paciente
              session = Session()
              session.description = 'This is a rehabilitation session for a patient. This register session ' \
                            'will be completed for the medical personal
              session.status = 'PLA'
              session.participants = 'By define'
              session.period = 'By define'
              session.game_levels = 'By define'
              session.iterations = 0
              session.movements = 'By define'
              session.games = 'By define'
              session.medical = MedicalProfile.objects.create(user=self)
              session.therapist = TherapistProfile.objects.create(user=self)
              session.patient = PatientProfile.objects.create(user=self)
              session.save()
  
  
      class Meta:
          db_table = 'auth_user'
  

• MedicalProfilemodel( userprofile/models.py)

  class MedicalProfile(models.Model):
      user = models.OneToOneField(settings.AUTH_USER_MODEL, on_delete=models.CASCADE)
      name = models.CharField(max_length=64)
      specialty = models.CharField(max_length=64)
      def __str__(self):
          return '%s %s' % (self.user.first_name, self.user.last_name)
  

• PatientProfilemodel( userprofile/models.py)

  class PatientProfile(models.Model):
      user = models.OneToOneField(settings.AUTH_USER_MODEL, on_delete=models.CASCADE)
      name = models.CharField(max_length=64)
      blood_type = models.CharField(max_length=4, blank=False)
      care_provider = models.CharField(max_length=64, blank=False)
      time_of_evolution = models.CharField(max_length=64, blank=False)
      affected_limb = models.CharField(max_length=64, blank=False)
      diagnostic = models.TextField(blank=True)
      managing_organization = models.CharField(max_length=64, blank=False)
  
      def __str__(self):
          return '%s %s' % (self.user.first_name, self.user.last_name)
  

• TherapistProfilemodel( userprofile/models.py)

  class TherapistProfile(models.Model):
      user = models.OneToOneField(settings.AUTH_USER_MODEL, on_delete=models.CASCADE)
      name = models.CharField(max_length=64)
      specialty = models.CharField(max_length=64)
  
      def __str__(self):
          return '%s %s' % (self.user.first_name, self.user.last_name)
  

rbsessions application

I mentioned at the beginning that I have another application called rbsessionsfrom which the therapy or rehabilitation sessions of the patients will be managed, so there is a model called Sessions.

• Sessionsmodel (rbsessions/models.py)

  from django.db import models
  from django.utils import timezone
  
  # Create your models here.
  class Session(models.Model):
  
      STATUS_PLANNED = 'PLA'
      STATUS_ARRIVED = 'ARR'
      STATUS_IN_PROGRESS = 'PRO'
      STATUS_ON_LEAVE = 'ONL'
      STATUS_FINISHED = 'FIN'
      STATUS_CANCELLED = 'CAN'
  
      STATUS_CHOICES = (
          (STATUS_PLANNED, u'Planned'),
          (STATUS_ARRIVED, u'Arrived'),
          (STATUS_IN_PROGRESS, u'In progress'),
          (STATUS_FINISHED, u'Finished'),
          (STATUS_CANCELLED, u'Cancelled'),
      )
  
      description = models.TextField(blank=False)
      date_session = models.DateTimeField(default=timezone.now())
      status = models.CharField(max_length=3,
          choices=STATUS_CHOICES,
          default=STATUS_PLANNED)
      participants = models.TextField(blank=False)
      period = models.CharField(max_length=25,blank=True)
      game_levels = models.TextField(blank=True)
      iterations = models.PositiveIntegerField(blank=True)
      movements = models.TextField(blank=False)
      games = models.TextField(blank=False)
      #slug = models.SlugField(max_length=100, blank=True)
  
      #Claves foráneas.
  
      medical = models.ForeignKey('userprofile.MedicalProfile')
      patient = models.ForeignKey('userprofile.PatientProfile')
      therapist = models.ForeignKey('userprofile.TherapistProfile')
  

As we can detail, this model has three foreign keys that point to the doctor and physiotherapist users who will be in charge of the session and another to the patient user who will carry it out. My problem that I will state now has to do with this.

When I want to create a patient user, I want them to be automatically assigned a session where they will be treated. In other words, an instance of the class is created for that patient user that was registered Session.

And this is how in userprofile/models.pythe User class (like this above but I indicate it here again), in this portion of code I ask:

If you are creating a patient user (is_patient checked), create your profile in PatientProfile and immediately create an instance of it Sessionwith all its corresponding fields or attributes:

The code on how I'm doing it is like this:

class User(AbstractUser):
     ...
def save(self, *args, **kwargs):
    user = super(User, self).save( *args, **kwargs)       
    # creating users with  other profiles
    if self.is ...
    ...
    # Creating and user with patient profile
    elif self.is_patient and not PatientProfile.objects.filter(user=self).exists():
        profile = PatientProfile(user=self)
        profile.save()

        #Creando la instancia Session que sera la sesión de rehabilitación de ese paciente que se esta creando
        session = Session()
        session.description = 'This is a rehabilitation session for a patient. This register session ' \
                              'will be completed for the medical personal'
        session.status = 'PLA'
        session.participants = 'By define'
        session.period = 'By define'
        session.game_levels = 'By define'
        session.iterations = 0
        session.movements = 'By define'
        session.games = 'By define'
        session.medical = MedicalProfile.objects.create(user=self)
        session.therapist = TherapistProfile.objects.create(user=self)
        session.patient = PatientProfile.objects.create(user=self)
        session.save()

When via Django admin I create a user with the patient profile ( is_patientchecked) I get this.

What IntegrityErrorI get is because I am saving an instance of the class Sessionwithin the override of the method save()that I am performing as well. And in fact before recording Session I call a .save() where I record the patient's profile

So thanks to those save()successive Django records the same user twice.

I have a .saveinside the def function save()like this

def save(self, *args, **kwargs): user = super(User, self).save( *args, **kwargs)

# Creating and user with patient profile
if self.is_patient and not PatientProfile.objects.filter(user=self).exists():
    profile = PatientProfile(user=self)
    profile.save()
    #Primer save

    session = Session()
    session.description = 'This is a rehabilitation session for a patient. This register session ' \
                          'will be completed for the medical personal'
    session.status = 'PLA'
    session.participants = 'By define'
    session.period = 'By define'
    session.game_levels = 'By define'
    session.iterations = 0
    session.movements = 'By define'
    session.games = 'By define'
    session.medical = MedicalProfile.objects.create(user=self)
    session.therapist = TherapistProfile.objects.create(user=self)
    session.patient = PatientProfile.objects.create(user=self)
    session.save()
    #Segundo save()

I am right?

Something that I wanted to try according to things that had been suggested to me and had also been done before was that instead of recording the instance of Sessiona patient user that is created within the override of the method save(), I used a signal post_save()to tell Django that when it creates the patient user, create your therapy session.

So I removed the creation of a patient session in the methodsave()

def save(self, *args, **kwargs):
    user = super(User, self).save( *args, **kwargs)

    # Creating and user with patient profile
    if self.is_patient and not PatientProfile.objects.filter(user=self).exists():
        profile = PatientProfile(user=self)
        profile.save()

And I said the following:

# Signal for save rehabilitation_session of a patient user
@receiver(post_save, sender = settings.AUTH_USER_MODEL)
def creating_rehabilitation_session_patient(sender, instance, **kwargs):
    user = instance
    #if created:
    if user.is_patient:
        Session.objects.create(description='This is a rehabilitation session for a patient. This register session'
                               'will be completed for the medical personal',
                               status='PLA', participants='By define', period='By define',
                               game_levels='By define', iterations=0, movements='By define',
                               games='By define',)

But here it happens to me that I don't know how to tell Django that in Session.objects.create(...)what I'm doing, I include the values ​​of the attributes medical, patient, therapist( they go after games in the code immediately above) that are foreign keys of the models MedicalProfile, PatientProfileand TherapistProfilethat are related to the modelSession

Apparently with this signal when saving the data, I don't know if it will work, since I also get an IntegrityError, but not because my user already exists in the system (like the previous one), but because since I am not sending values ​​to the fields medical, patient, therapistand these don't accept null values ​​so they can't be empty.

I don't know if the idea of ​​applying the signal post_save()to my function will def creating_rehabilitation_session_patient()solve my problem and in which case...

What is the best way to send the parameters of the fields medical, patient, therapist?

Although I don't know if maybe once I can send the fields to it medical, patientI therapistalso get the IntegrityError already userprofile exist error correctly (the first one I got), given that finally it is in the override of the save() method or with a signal, I'm finally doing a save... although with the signal it's after... I don't know if my analysis is correct.

How can I achieve this?

UPDATE

I have modified according to the answer I got, the fields session.medical, session.therapist, session.patientin the class Sessioninrbsessions/models.py

Now I am calling the functions that return the respective profile of each user, like this:

def save(self, *args, **kwargs):
    user = super(User, self).save( *args, **kwargs)

    # Creating and user with patient profile
    if self.is_patient and not PatientProfile.objects.filter(user=self).exists():
        profile = PatientProfile(user=self)
        profile.save()
        #Primer save

        session = Session()
        session.description = 'This is a rehabilitation session for a patient. This register session ' \
                          'will be completed for the medical personal'
        session.status = 'PLA'
        session.participants = 'By define'
        session.period = 'By define'
        session.game_levels = 'By define'
        session.iterations = 0
        session.movements = 'By define'
        session.games = 'By define'

        #Imrpimo el valor de lo que me retorna get_medical_profile()
        print (self.get_medical_profile())

        session.medical = self.get_medical_profile()
        session.therapist = self.get_therapist_profile()
        session.patient = self.get_patient_profile()
        session.save()
        #Segundo save()

Pero al examinar el contenido de lo que me retorna la función get_medical_profile(), detallo que le estoy enviando el valor de None al momento de crear una instancia de la clase Session

[21/Jan/2016 21:40:30] "POST /admin/userprofile/user/add/ HTTP/1.1" 302 0
[21/Jan/2016 21:40:30] "GET /admin/userprofile/user/26/change/ HTTP/1.1" 200 24279
[21/Jan/2016 21:40:30] "GET /admin/jsi18n/ HTTP/1.1" 200 3189
None
Internal Server Error: /admin/userprofile/user/26/change/
Traceback (most recent call last):
  File "/home/bgarcial/.virtualenvs/nrb_dev/lib/python3.4/site-packages/django/core/handlers/base.py", line 149, in get_response
    response = self.process_exception_by_middleware(e, request)
  File "/home/bgarcial/.virtualenvs/nrb_dev/lib/python3.4/site-packages/django/core/handlers/base.py", line 147, in get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/home/bgarcial/.virtualenvs/nrb_dev/lib/python3.4/site-packages/django/contrib/admin/options.py", line 541, in wrapper
    return self.admin_site.admin_view(view)(*args, **kwargs)
  File "/home/bgarcial/.virtualenvs/nrb_dev/lib/python3.4/site-packages/django/utils/decorators.py", line 149, in _wrapped_view
    response = view_func(request, *args, **kwargs)
  File "/home/bgarcial/.virtualenvs/nrb_dev/lib/python3.4/site-packages/django/views/decorators/cache.py", line 57, in _wrapped_view_func
    response = view_func(request, *args, **kwargs)
  File "/home/bgarcial/.virtualenvs/nrb_dev/lib/python3.4/site-packages/django/contrib/admin/sites.py", line 244, in inner
    return view(request, *args, **kwargs)
  File "/home/bgarcial/.virtualenvs/nrb_dev/lib/python3.4/site-packages/django/contrib/admin/options.py", line 1438, in change_view
    return self.changeform_view(request, object_id, form_url, extra_context)
  File "/home/bgarcial/.virtualenvs/nrb_dev/lib/python3.4/site-packages/django/utils/decorators.py", line 67, in _wrapper
    return bound_func(*args, **kwargs)
  File "/home/bgarcial/.virtualenvs/nrb_dev/lib/python3.4/site-packages/django/utils/decorators.py", line 149, in _wrapped_view
    response = view_func(request, *args, **kwargs)
  File "/home/bgarcial/.virtualenvs/nrb_dev/lib/python3.4/site-packages/django/utils/decorators.py", line 63, in bound_func
    return func.__get__(self, type(self))(*args2, **kwargs2)
  File "/usr/lib/python3.4/contextlib.py", line 30, in inner
    return func(*args, **kwds)
  File "/home/bgarcial/.virtualenvs/nrb_dev/lib/python3.4/site-packages/django/contrib/admin/options.py", line 1378, in changeform_view
    self.save_model(request, new_object, form, not add)
  File "/home/bgarcial/.virtualenvs/nrb_dev/lib/python3.4/site-packages/django/contrib/admin/options.py", line 991, in save_model
    obj.save()
  File "/home/bgarcial/workspace/neurorehabilitation-system/userprofile/models.py", line 141, in save
    session.medical = self.get_medical_profile()
  File "/home/bgarcial/.virtualenvs/nrb_dev/lib/python3.4/site-packages/django/db/models/fields/related_descriptors.py", line 199, in __set__
    (instance._meta.object_name, self.field.name)
ValueError: Cannot assign None: "Session.medical" does not allow null values.

Y es normal claro, porque en mis funciones de profiles, inicialmente los profiles respectivos son inicializados a None

# We get the profiles user according with their type
    def get_medical_profile(self):
        medical_profile = None
        #medical_profile = MedicalProfile.objects.get(user=self)
        if hasattr(self, 'medicalprofile'):
            medical_profile=self.medicalprofile
        return medical_profile

    def get_patient_profile(self):
        patient_profile = None
        if hasattr(self, 'patientprofile'):
            patient_profile = self.patientprofile
        return patient_profile

    def get_therapist_profile(self):
        therapist_profile = None
        if hasattr(self, 'therapistprofile'):
            therapist_profile = self.therapistprofile
        return therapist_profile

Creo que al preguntar lo que voy a preguntar ahora tal vez no he acabado de comprender como trabajan las funciones get de los profiles, dado que estas han sido inicializadas a None pensaría con el objetivo de que cuando no existan las relaciones OneToOne no tengamos el error de RelatedObjectDoesNotExist (¿?)

Intenté cambiar este valor o equivalente por esta linea

medical_profile = MedicalProfile.objects.get(self.user.first_name)

Pero obtuve esto.

AttributeError at /admin/userprofile/user/31/change/
'User' object has no attribute 'user'
Request Method: POST
Request URL:    http://localhost:8000/admin/userprofile/user/31/change/
Django Version: 1.9
Exception Type: AttributeError
Exception Value:    
'User' object has no attribute 'user'
Exception Location: /home/bgarcial/workspace/neurorehabilitation-system/userprofile/models.py in get_medical_profile, line 158
Python Executable:  /home/bgarcial/.virtualenvs/nrb_dev/bin/python
Python Version: 3.4.3
Python Path:    
['/home/bgarcial/workspace/neurorehabilitation-system',
 '/home/bgarcial/.virtualenvs/nrb_dev/lib/python3.4',
 '/home/bgarcial/.virtualenvs/nrb_dev/lib/python3.4/plat-x86_64-linux-gnu',
 '/home/bgarcial/.virtualenvs/nrb_dev/lib/python3.4/lib-dynload',
 '/usr/lib/python3.4',
 '/usr/lib/python3.4/plat-x86_64-linux-gnu',
 '/home/bgarcial/.virtualenvs/nrb_dev/lib/python3.4/site-packages']
Server time:    Thu, 21 Jan 2016 22:19:37 +0000

En estos momentos no comprendo como debo manejar el valor retornado de las funciones get_medical_profile, y demás. De pronto puedes explicarme su funcionamiento por favor. Entre otras cosas porque se pregunta por el atributo de esta forma:

if hasattr(self, 'patientprofile'):

Gracias y disculpas