Equivalent between `MySQL JOIN` and Django - mysql

Question

I'm using Django 1.11 and I would like to get the correct syntax in order to translate my MySQL Join request to Django QuerySet Syntax.
I have 3 different models (1 Model in my Identity application and 2 Models in my Fiscal application) as following :
#Identity.Individu
class Individu(models.Model):
NumeroIdentification = models.CharField(max_length=30, null=True, verbose_name='Numero Identification physique', unique=True)
Civilite = models.CharField(max_length=12,choices=CHOIX_TITRE, verbose_name='Civilité')
NomJeuneFille = models.CharField(max_length=30, verbose_name='Nom de jeune fille', blank=True)
Nom = models.CharField(max_length=30, verbose_name='Nom de famille')
Prenom = models.CharField(max_length=30, verbose_name='Prénom(s)')
#Fiscal.Profession
class Profession (models.Model) :
Employe = models.ForeignKey(Individu, related_name='Individu', verbose_name='Individu', null=False, to_field='NumeroIdentification')
Entreprise = models.ForeignKey(Societe, related_name='Société', verbose_name='Société', null=False, to_field='NumeroIdentification')
NumeroImpot = models.CharField(max_length=30, null=True, verbose_name='Numéro Imposition', unique=True)
Profession = models.CharField(max_length=30, verbose_name='Profession')
#Fiscal.Salaire
class Salaire (models.Model) :
Employe = models.ForeignKey(Individu, related_name='Salaire_Individu', verbose_name='Salaire_Individu', null=False, to_field='NumeroIdentification')
Salaire_B_mensuel = models.IntegerField(verbose_name='Salaire Brut Mensuel')
Salaire_N_mensuel = models.IntegerField(verbose_name='Salaire Net Mensuel')
With Mysql, I have this request which works fine :
SELECT * FROM Identity_individu i
INNER JOIN Fiscal_profession p ON i.NumeroIdentification = p.Employe_id
INNER JOIN Fiscal_salaire s on i.NumeroIdentification = s.Employe_id;
I thing I have to use prefetch_related and I wrote this (first step, join between two tables) :
#login_required
def FiscalReporting(request) :
Contribuable = Individu.objects.prefetch_related("Profession").all().filter(NumeroIdentification=Profession.Employe)
context = {
"Contribuable" : Contribuable,
}
return render(request, 'Fiscal_Reporting.html', context)
And in my template :
<table style="width:120%">
<tbody>
<tr>
<th>ID</th>
<th>État</th>
<th>N° Identification</th>
<th>Civilité</th>
<th>Nom</th>
<th>Prénom</th>
<th>Date de Naissance</th>
<th>N° Fiscal</th>
<th>Salaire Annuel Net</th>
</tr>
{% for item in Contribuable %}
<tr>
<td>{{ item.id}}</td>
<td>{{ item.Etat}}</td>
<td>{{ item.NumeroIdentification}}</td>
<td>{{ item.Civilite }}</td>
<td>{{ item.Nom }}</td>
<td>{{ item.Prenom }}</td>
<td>{{ item.DateNaissance }}</td>
<td>{{ item.NumeroImpot }}</td>
<td>{{ item.Employe.Salaire_N_annuel }}</td>
</tr>
{% endfor %}
</tbody>
</table>
Any idea about my issue ? I don't find any result up to now because my array is empty :/
Then, How I can add a supplementary join in my Django QuerySet ?

Answer 1

You can use prefetch_related to prefetch more than one related table like this:
Contribuable = Individu.objects.prefetch_related("Individu", "Salaire_Individu")
Note that I use "Individu" related_name of Profession model as prefetch_related argument.
Now in template you can iterate over each profession and Salaire_Individu like this:
{% for item in Contribuable %}
...
<td>{{ item.Nom }}</td>
{% for profession in item.Individu.all %}
<td>{{ profession.NumeroImpot }}</td>
{% endfor %}
{% for salary in item.Salaire_Individu.all %}
<td>{{ salary.Salaire_B_mensuel }}</td>
{% endfor %}
{% endfor %}