Foreign key in Django assignment

How Django foreign key constraint assignment

Look at reverse generated model.py

class ScDetail(models.Model):
    bac_name = models.ForeignKey('ScMain', related_name='SCMain7',on_delete=models.CASCADE,db_column='bac_name', blank=True, null=True)
    pro = models.ForeignKey('ScMain',  related_name='SCMain8',on_delete=models.CASCADE,db_column='pro_id',blank=True, null=True)
    fajiaoguan = models.CharField(max_length=255, blank=True, null=True)
    fajiaotiji = models.IntegerField(blank=True, null=True)
    junniliang = models.IntegerField(blank=True, null=True)
    baohujitianjialiang = models.IntegerField(blank=True, null=True)
    tanpanliang1_field = models.FloatField( blank=True, null=True)
    tanpanliang2_field = models.FloatField( blank=True, null=True)
    tanpanliang3_field = models.FloatField( blank=True, null=True)
    chufenliang = models.IntegerField(blank=True, null=True)

    class Meta:
        managed = False
        db_table = 'sc_detail'


class ScMain(models.Model):
    bac_name = models.CharField(max_length=20)
    pro_id = models.CharField(max_length=20)
    pro_date = models.DateField()
    user = models.ForeignKey('Users', models.DO_NOTHING)
    insert_time = models.DateTimeField()

    class Meta:
        managed = False
        db_table = 'sc_main'

ScMain want to find the data in the assigned ScDetail in bac_name and pro

First look at me through the pit. . . . . .

#ERROR:Cannot assign "'aa'": "ScDetail.bac_name" must be a "ScMain" instance.
detail_data.bac_name = sc_data.bac_name
detail_data.pro_id = sc_data.pro_id

# ERROR:Manager isn't accessible via ScMain instances
detail_data.bac_name = ScMain().objects.get(id=sc_data.id).bac_name
detail_data.pro_id = ScMain().objects.get(id=sc_data.id).pro_id

The correct way:

qs = ScMain.objects.filter(id=id1).first()
detail_data.bac_name = qs
detail_data.pro = qs

Personal understanding:

qs eventual return is a queryset, understood as an array

models.py is reverse generated, an association has been formed foreign key, assigned directly to

bac_name and pro detail_data is finally stored in the primary key of the id value ScMain

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