Django - populate model with foreignkey via csv import? - django

Question

I've trying to setup a model to be populated with a csv file, and to use one of the fields as a foreignkey:
First, I tried creating a model from an existing postgresql table using inspectdb, migrating and then change the type of the field I want to relate from charfield to foreignkey, but I got errors
Then I tried creating an empty model with the inspectdb description, then importing a csv in postgresql, and finally changing the field i want to foreignkey. In the admin site I can view the imported data and the relations, but when I query the model I got another error with the foreignkey field, and it wont let me migrate (cant recognize the charfield, it asks for integer)
-the csv column I want for a foreignkey is charfield, when i create the model before importing the csv i got an error, then checking the datatype in the postgres table is says integer, can it be set to charfield??
What workflow work best for importing a csv to a model and use one of the fields as a foreignkey (charfield type)??
Thanks
This is the model to be related to :
class D_Roles(models.Model):
predio = models.CharField(max_length=254)
dest = models.CharField(max_length=254)
dir = models.CharField(max_length=254)
rol = models.CharField(max_length=254)
vlr_tot = models.FloatField()
ub_x2 = models.FloatField()
ub_y2 = models.FloatField()
instrum = models.CharField(max_length=254)
codzona = models.CharField(max_length=254)
nomzona = models.CharField(max_length=254)
geom = models.MultiPointField(srid=32719)
def __str__(self):
return self.rol
class Meta():
verbose_name_plural = "Roles SII"
The models I want to populate with csv:
class Dom2015CertInf(models.Model):
id = models.CharField(primary_key=True, max_length=80)
nombre_archivo = models.CharField(max_length=180, blank=True, null=True)
derechos = models.CharField(max_length=120, blank=True, null=True)
dir_calle = models.CharField(max_length=120, blank=True, null=True)
dir_numero = models.CharField(max_length=120, blank=True, null=True)
fecha_certificado = models.CharField(max_length=50, blank=True, null=True)
numero_certificado = models.CharField(max_length=50, blank=True, null=True)
numero_solicitud = models.CharField(max_length=50, blank=True, null=True)
#Original field from inspectdb
#rol_sii = models.CharField(max_length=50, blank=True, null=True)
#FOREIGNKEY Changed after creating the model and importing the csv
rol_sii = models.ForeignKey(D_Roles, db_column='rol_sii', on_delete=models.CASCADE, default=0)
zona_prc = models.CharField(max_length=120, blank=True, null=True)
def __str__(self):
return str(self.numero_certificado)
class Meta:
managed = True
verbose_name_plural = "2015 Certificados Informaciones Previas"
ordering = ['numero_certificado']