How to Left Join Model (or) Table in DRF - mysql

Question

I have two models Employee and AccessDr.
Employee Model=>
class Employee(models.Model):
empid = models.CharField(max_length=20, unique=True)
empname = models.CharField(max_length=50)
phone = models.CharField(max_length=20, blank=True)
token = models.ForeignKey(
Company, to_field='token', on_delete=models.CASCADE)
def __str__(self):
return "%s" % (self.empid)
class Meta:
managed = True
db_table = 'employee'
AccessDr Model=>
class AccessDr(models.Model):
empid = models.ForeignKey(
Employee, to_field='empid', on_delete=models.CASCADE)
_date = models.DateField()
_time = models.IntegerField()
device = models.CharField(max_length=5)
takey = models.CharField(max_length=3, default='00')
token = models.ForeignKey(
Company, to_field='token', on_delete=models.CASCADE)
def __str__(self):
return "%s %s" % (self.empid, self._date)
class Meta:
ordering = ['_date']
managed = True
db_table = 'tstrdoor'
I would like to return object when the request to AccessDr like SQL left join, Example json=>
{
empid:'',
empname:'', <=this one from employee model
phone:'', <=this one from employee model
_date:'',
_time:'',
.
.
}
How can I achieve that one?

Answer 1

have a look at this LEFT JOIN Django ORM
read this as well https://docs.djangoproject.com/en/2.2/topics/db/queries/#spanning-multi-valued-relationships
you can print query to look at how it translates to SQL by
Employes=AccessDr.objects.values('employee__empname','employee__phone')
print(Employes.query)
Are you using serializers in the views? in this case, you could create a serializer field
which will put agreement data as an array like this
class CustomerSerializer(serializers.ModelSerializer):
agreements = AgreementSerializer(many=True, read_only=True)
class Meta:
model = Customer
fields = [
'id',
'username',
'mail',
'fName',
'lName',
'fNameEng',
'lNameEng',
'personalId',
'phone',
'crmId', # "ID": "20995",
'agreements',
]
depth = 1
Are you using serializers in the views? in this case, you could create serializer field
which will put agreement data as an array like this
{
"id": 985,
"username": null,
"mail": "undefined",
"fName": "Merab",
"lName": "Dasv",
"fNameEng": "Merab",
"lNameEng": "Dasv",
"personalId": "01022342346003629",
"phone": "5912324234282331",
"crmId": 1439,
"agreements": [
{
"id": 884,
"signDate": "2015-04-16",
"accountDate": "2015-05-01",
"amount": 0,
"comBalance": -1445.0,
"status": 1,
"details": [
{
"square": 32.38,
"amount": 35.0,
"object": {
"id": 578,
"object": 2,
"block": 1,
"floor": 19,
"flat": "7",
"cadastre": "05.24.04.055.01.563",
"square": 32.38,
"pCounter": 25915123146,
"wCounter": 104412312435,
"accountDate": "2015-04-01T00:00:00",
"comBalance": -1445.0,
"comDeptAmount": 1895.0,
"rentDate": null,
"active": 1,
"finaAmount": 0,
"crmId": 0
}
},
]
},
]
}