带主键的原始查询

Question

My model

class Despacho (models.Model):  
    bus=models.ForeignKey(Bus)  
    contador = models.IntegerField()
    cerrado = models.BooleanField(editable=False)

class Bus(models.Model):    
    numero_bus=models.CharField(max_length=255,unique=True)
    en_ruta = models.BooleanField(editable=False)   

I need a query to extract the data which I save a bus, and I enter a number of the bus and I need to know if there is a dispatch that matches the search try to do the following query

my database is postgresql

d = Despacho.objects.raw('''SELECT * FROM operaciones_despacho WHERE operaciones_despacho.bus =  '%s' AND operaciones_despacho.cerrado = '%s'                                                    
;'''%(bus.numero_bus,False)) 

error : column operaciones_despacho.bus does not exist

Answer 1

First up in Django, we use raw sql only in the rare instances when it's particularly hard to write an ORM query. In this instance, writing an ORM query is much easier and shorter than a raw query.

Despacho.objects.filter(bus=bus).filter(cerrado=False)

On those rare instances when you need to do a raw query, take care you use the params argument to raw instead of string formatting. The correct way to write your raw query is

Despacho.objects.raw('''SELECT * FROM operaciones_despacho WHERE operaciones_despacho.bus =  '%s' AND operaciones_despacho.cerrado = '%s'''' ,
 [bus.numero_bus,False]) 

But I emphasis once again that you should not be using a raw query here because it's a simple ORM query.