In my project i have an SQL query for extract some results from two tables like thisone:
SELECT
read_date, unit_id, device_id, proj_code, var_val
FROM
public.api_site_varsresults AS SV, public.api_site_results AS SR
WHERE
(read_date >= '2021-06-21' AND read_date <= '2021-06-24') AND SV.id_res_id = SR.id
here my models:
class Results(models.Model):
id = models.AutoField(primary_key=True)
device = models.ForeignKey(Device, null=True, on_delete=models.SET_NULL)
proj_code = models.CharField(max_length=400)
res_key = models.SlugField(max_length=80, verbose_name="Message unique key", unique=True)
read_date = models.DateTimeField(verbose_name="Datetime of vals readings")
unit = models.ForeignKey(ModbusDevice, null=True, on_delete=models.SET_NULL)
def __str__(self):
return self.device
class Meta:
indexes = [
models.Index(fields=['device', 'unit', 'proj_code']),
]
class VarsResults(models.Model):
id = models.AutoField(primary_key=True)
id_res = models.ForeignKey(Results, related_name="mainres", on_delete=models.CASCADE)
var_id = models.ForeignKey(ModbusVariable, null=True, on_delete=models.SET_NULL)
var_val = models.CharField(max_length=400, blank=True)
var_hash = models.CharField(max_length=400)
def __str__(self):
return self.var_hash
class Meta:
indexes = [
models.Index(fields=['id_res', 'var_id']),
]
i wolud to use this query in my django project using ORM but i try to do :
varsresults.objects.filter(<conditions>).fields(<fields>)
but is not correct, i don't know how i can link two tables, select specific fields and filter for that condition in django ORM
Can someone help me please? So many thanks in advance
Manuel
