Django - Update one field after form submitting

Question

I'm looking for update my Django form after user submission. I filled my BirthCertificateForm with some data and I just have one field which is not filled : social_number.

Why ? Because after submitting form, I created a unique social number from data form. So, I would like to update my previous form and add this social number according to the good field and validate it.

My models.py file looks like :

class BirthCertificate(models.Model):

    lastname = models.CharField(max_length=30, null=False, verbose_name='Nom de famille')
    firstname = models.CharField(max_length=30, null=False, verbose_name='Prénom(s)')
    sex = models.CharField(max_length=8, choices=SEX_CHOICES, verbose_name='Sexe')
    birthday = models.DateField(null=False, verbose_name='Date de naissance')
    birthhour = models.TimeField(null=True, verbose_name='Heure de naissance')
    birthcity = models.CharField(max_length=30, null=False, verbose_name='Ville de naissance')
    birthcountry = CountryField(blank_label='Sélectionner un pays', verbose_name='Pays de naissance')
    fk_parent1 = models.ForeignKey(Person, related_name='ID_Parent1', verbose_name='ID parent1', null=False)
    fk_parent2 = models.ForeignKey(Person, related_name='ID_Parent2', verbose_name='ID parent2', null=False)
    mairie = models.CharField(max_length=30, null=False, verbose_name='Mairie')
    social_number = models.CharField(max_length=30, null=True, verbose_name='numero social')
    created = models.DateTimeField(auto_now_add=True)

And my views.py file have 2 functions :

First function :

# First function which let to fill the form with some conditions / restrictions

@login_required
def BirthCertificate_Form(request) :
    # Fonction permettant de créer le formulaire Acte de Naissance et le remplissage


    query_lastname_father = request.GET.get('lastname_father')
    query_lastname_mother = request.GET.get('lastname_mother')

    if request.method == 'POST':

        form = BirthCertificateForm(request.POST or None)

        if form.is_valid() :   # Vérification sur la validité des données
            post = form.save()
            return HttpResponseRedirect(reverse('BC_treated', kwargs={'id': post.id}))

    else:
        form = BirthCertificateForm()


        parent1 = Person.objects.filter(lastname=query_lastname_father)
        parent2 = Person.objects.filter(lastname=query_lastname_mother)

        form = BirthCertificateForm(request.POST or None)
        form.fields['fk_parent1'].queryset = parent1.filter(sex="Masculin")
        form.fields['fk_parent2'].queryset = parent2.filter(sex="Feminin")

    context = {
        "form" : form,
        "query_lastname" : query_lastname_father,
        "query_lastname_mother" : query_lastname_mother,
    }

    return render(request, 'BC_form.html', context)

Second function :

# Second function which resume the previous form and create my social number

@login_required
def BirthCertificate_Resume(request, id) :

    birthcertificate = get_object_or_404(BirthCertificate, pk=id)

    #Homme = 1 / Femme = 2
    sex_number = []
    if birthcertificate.sex == 'Masculin' :
        sex_number = 1
        print sex_number
    else :
        sex_number = 2
        print sex_number

    #Récupère année de naissance
    birthyear_temp = str(birthcertificate.birthday.year)
    birthyear_temp2 = str(birthyear_temp.split(" "))
    birthyear = birthyear_temp2[4] + birthyear_temp2[5]

    #Récupère mois de naissance
    birthmonth_temp = birthcertificate.birthday.month
    if len(str(birthmonth_temp)) == 1 :
        birthmonth = '0' + str(birthmonth_temp)
    else :
        birthmonth = birthmonth_temp

    #Récupère N° Mairie (ici récupère nom mais sera changé en n°)
    birth_mairie = birthcertificate.mairie
    print birth_mairie

    #Génère un nombre aléaloire :
    key_temp = randint(0,999)
    if len(str(key_temp)) == 1 :
        key = '00' + str(key_temp)
    elif len(str(key_temp)) ==2 :
        key = 'O' + str(key_temp)
    else :
        key = key_temp
    print key

    social_number = str(sex_number) + ' ' + str(birthyear) + ' ' + str(birthmonth) + ' ' + str(birth_mairie) + ' - ' + str(key)
    print social_number

    return render(request, 'BC_resume.html', {"birthcertificate" : birthcertificate})

My question is : How I can take again my form and modify it in order to fill thesocial_number field just created ?

Thank you !

Answer 1

I found a solution which works in order to update my models.

I had this function :

@login_required
def BirthCertificate_Resume(request, id) :

    birthcertificate = get_object_or_404(BirthCertificate, pk=id)

    #Homme = 1 / Femme = 2
    sex_number = []
    if birthcertificate.sex == 'Masculin' :
        sex_number = 1
        print sex_number
    else :
        sex_number = 2
        print sex_number

    #Récupère année de naissance
    birthyear_temp = str(birthcertificate.birthday.year)
    birthyear_temp2 = str(birthyear_temp.split(" "))
    birthyear = birthyear_temp2[4] + birthyear_temp2[5]

    #Récupère mois de naissance
    birthmonth_temp = birthcertificate.birthday.month
    if len(str(birthmonth_temp)) == 1 :
        birthmonth = '0' + str(birthmonth_temp)
    else :
        birthmonth = birthmonth_temp

    # #Récupère première lettre nom 
    # lastname_temp = birthcertificate.lastname
    # lastname = lastname_temp[0]
    # print lastname

    # #Récupère première lettre prénom 
    # firstname_temp = birthcertificate.firstname
    # firstname = firstname_temp[0]
    # print firstname


    #Récupère N° Mairie (ici récupère nom mais sera changé en n°)
    birth_mairie = birthcertificate.mairie
    print birth_mairie

    #Génère un nombre aléaloire :
    key_temp = randint(0,999999)
    if len(str(key_temp)) == 1 :
        key = '00000' + str(key_temp)
    elif len(str(key_temp)) == 2 :
        key = '0000' + str(key_temp)
    elif len(str(key_temp)) == 3 :
        key = '000' + str(key_temp)
    elif len(str(key_temp)) == 4 :
        key = '00' + str(key_temp)
    elif len(str(key_temp)) == 5 :
        key = '0' + str(key_temp)
    else :
        key = key_temp
    print key

    social_number = str(sex_number) + ' ' + str(birthyear) + ' ' + str(birthmonth) + ' ' + str(birth_mairie) + ' - ' + str(key) 
    print social_number


    return render(request, 'BC_resume.html', {"birthcertificate" : birthcertificate, "social_number" : social_number})

So I just add two lines and it seems to work pretty well :

birthcertificate.social_number = social_number
birthcertificate.save()

What do you think about this method ?

Answer 2

For starters, I would recommend you refer to this article and this article.

Now, based on what you're trying to do, I would write the post_save in your models.py where you have your model defined. Thus, this is what it would look like:

from django.db import models
from django.dispatch import receiver
from django.db.models.signals import post_save


class BirthCertificate(models.Model):
    ...  # your model attributes


# Here is where the post_save hook happens
@receiver(post_save, sender=BirthCertificate, dispatch_uid='generate_social_number')  # You can name the dispatch_uid whatever you want
def gen_social(sender, instance, **kwargs):
    if kwargs.get('created', False):
        # Auto-generate the social number
        # This is where you determine the sex number, birth year, birth month, etc. that you have calculated in your views.py.
        # Use the instance object to get all the model attributes.
        # Example: I'll calculate the sex number for you, but I leave the other calculations for you to figure out.
        if instance.sex == 'Masculin':
            sex_number = 1
        else:
            sex_number = 2

        ...  # Calculate the other variables that you will use to generate your social number
        ...  # More lines to create the variables

        instance.social_number = str(sex_number) + ...  # Now set the instance's social number with all the variables you calculated in the above steps
        instance.save()  # Finally your instance is saved again with the generated social number

NOTE: I'm assuming you want to generate the social_number when a birth certificate record is newly created, not when you're making a modification to an existing record. That's why I used the if kwargs.get('created', False) conditional. This conditional basically checks if you're creating a new record or modifying an existing one. If you want this post_save to run even after modifying a record, then remove the condition.