Django Queryset gibt keine eindeutigen Werte zurück

Question

Ich habe eine Abfrage, die aus irgendeinem Grund keine eindeutigen Werte zurückgibt, obwohl ich eindeutig angegeben habe, ich dachte, es könnte wegen der einzigen sein, also habe ich das entfernt, aber die Liste ist immer noch die gleiche

circuit_providers = CircuitInfoData.objects.only('provider').values('provider').distinct() 

ich nur eine Liste von unqiue Anbieter wollen

model.py

from __future__ import unicode_literals 
from django.db import models 
import string 
import random 
import time 
import os 

# Create your models here. 
from service.models import ServiceContacts 

def site_photos_path(instance, filename): 
    file ,extension = os.path.splitext(filename) 
    # file will be uploaded to MEDIA_ROOT/user_<id>/<filename> 
    chars=string.ascii_uppercase + string.digits 
    random_string = ''.join(random.choice(chars) for _ in range(6)) 
    filename = '%s-%s%s' % (random_string,time.strftime("%d-%m-%H-%M-%S"),extension) 
    return 'site_photos/{0}'.format(filename) 

def service_upload_path(instance, filename): 
    file ,extension = os.path.splitext(filename) 
    # file will be uploaded to MEDIA_ROOT/user_<id>/<filename> 
    chars=string.ascii_uppercase + string.digits 
    random_string = ''.join(random.choice(chars) for _ in range(6)) 
    filename = '%s-%s%s' % (random_string,time.strftime("%d-%m-%H-%M-%S"),extension) 
    return 'service_files/{0}'.format(filename)  

def site_files_path(instance, filename): 
    file ,extension = os.path.splitext(filename) 
    # file will be uploaded to MEDIA_ROOT/user_<id>/<filename> 
    chars=string.ascii_uppercase + string.digits 
    random_string = ''.join(random.choice(chars) for _ in range(6)) 
    filename = '%s-%s%s' % (random_string,time.strftime("%d-%m-%H-%M-%S"),extension) 
    return 'site_files/{0}'.format(filename) 

provider_choices = (
     ('KCOM','KCOM'), 
     ('BT','BT'), 
     ('EE','EE'), 
     ('THREE','THREE'), 
    ) 
circuit_choices = (
     ('DSL','DSL'), 
     ('VDSL','VDSL'), 
     ('MPLS','MPLS'), 
     ('4G','4G'), 
     ('Internet Leased Line','Internet Leased Line'), 
    )  

subnet_mask_choices = (
     ('/16','/16'), 
     ('/24','/24'), 
     ('/25','/25'), 
     ('/26','/26'), 
     ('/27','/27'), 
     ('/28','/28'), 
     ('/29','/29'), 
     ('/30','/30'), 
     ('/31','/31'), 
    )  

class ShowroomConfigData(models.Model): 
    location = models.CharField(max_length=50) 
    subnet = models.GenericIPAddressField(protocol='IPv4') 
    r1_loopback_ip = models.GenericIPAddressField(protocol='IPv4',verbose_name="R1 Loopback IP") 
    r2_loopback_ip = models.GenericIPAddressField(protocol='IPv4',verbose_name="R2 Loopback IP") 
    opening_date = models.DateField(verbose_name="Showroom opening date") 
    last_hw_refresh_date = models.DateField(verbose_name="Date of latest hardware refresh") 
    is_showroom = models.BooleanField(default=True,verbose_name="Is this site a showroom?") 

    class Meta: 
      verbose_name = "Showroom Data" 
      verbose_name_plural = "Showroom Data" 
      ordering = ('location',) 

    def __unicode__(self): 
     return self.location 


class MajorSiteInfoData(models.Model): 
    location = models.CharField(max_length=200) 
    major_subnet = models.GenericIPAddressField(protocol='IPv4',verbose_name="Major Site Subnet") 
    routed_subnet = models.GenericIPAddressField(protocol='IPv4',verbose_name="Routed Link Subnet") 
    bgp_as = models.CharField(max_length=6,verbose_name="BGP AS Number") 

    class Meta: 
      verbose_name = "Major Site Data" 
      verbose_name_plural = "Major Site Data"  

    def __unicode__(self): 
     return self.location 

class CircuitInfoData(models.Model):  
    showroom_config_data = models.ForeignKey(ShowroomConfigData,verbose_name="Install Showroom") 
    major_site_info = models.ForeignKey(MajorSiteInfoData,verbose_name="Install Site") 
    circuit_type = models.CharField(max_length=100,choices=circuit_choices)  
    circuit_speed = models.IntegerField(blank=True) 
    circuit_bearer = models.IntegerField(blank=True) 
    provider = models.CharField(max_length=200,choices=provider_choices) 
    ref_no = models.CharField(max_length=200,verbose_name="Reference No") 

    class Meta: 
     verbose_name = "Circuit Data" 
     verbose_name_plural = "Circuit Data" 
     ordering = ('showroom_config_data__location','circuit_speed') 

    def __unicode__(self): 
     return '%s | %s | %s | %s | %s' % (self.showroom_config_data.location,self.major_site_info.location, self.provider, self.service_type, self.ref_no) 

Ergebnisse von Shell unter

012.351.

[root@network-tools infternal]# python manage.py shell 
Python 2.7.5 (default, Nov 20 2015, 02:00:19) 
[GCC 4.8.5 20150623 (Red Hat 4.8.5-4)] on linux2 
Type "help", "copyright", "credits" or "license" for more information. 
(InteractiveConsole) 
>>> from networks.models import CircuitInfoData 
>>> d = CircuitInfoData.objects.values('provider').distinct() 
>>> for item in d: 
... print item 
... 
{'provider': u'BT'} 
{'provider': u'BT'} 
{'provider': u'KCOM'} 
{'provider': u'BT'} 
{'provider': u'BT'} 
{'provider': u'KCOM'} 
..... 
>>> print d.query 
SELECT DISTINCT "networks_circuitinfodata"."provider", "networks_showroomconfigdata"."location", "networks_circuitinfodata"."circuit_speed" FROM "networks_circuitinfodata" INNER JOIN "networks_showroomconfigdata" ON ("networks_circuitinfodata"."showroom_config_data_id" = "networks_showroomconfigdata"."id") ORDER BY "networks_showroomconfigdata"."location" ASC, "networks_circuitinfodata"."circuit_speed" ASC 
>>> 

eine Sache ive bemerkt, dass, wenn ich Artikel in der Schale drucken, wie oben

#### with def __unicode__(self): ##### 

>>> from networks.models import CircuitInfoData 
>>> d = CircuitInfoData.objects.only('provider').distinct() 
>>> for i in d: 
... print i 
... 
Location1 | Showroom | BT | DSL | N/A 
Location2 | Showroom | BT | MPLS | XXXX 
Location2 | Showroom | KCOM | MPLS | XXXX 
Location3 | Showroom | BT | MPLS | XXXX 
Location3 | Showroom | BT | DSL | N/A 
Location4 | Showroom | KCOM | MPLS | XXXXX 
... 

#### with out def __unicode__(self): ##### 

>>> from networks.models import CircuitInfoData 
>>> d = CircuitInfoData.objects.only('provider').distinct() 
>>> for i in d: 
... print i 
... 
CircuitInfoData_Deferred_circuit_bearer_circuit_cfb3d62ef325a6acfc8ddcb43c8ae1c6 object 
CircuitInfoData_Deferred_circuit_bearer_circuit_cfb3d62ef325a6acfc8ddcb43c8ae1c6 object 
CircuitInfoData_Deferred_circuit_bearer_circuit_cfb3d62ef325a6acfc8ddcb43c8ae1c6 object 
CircuitInfoData_Deferred_circuit_bearer_circuit_cfb3d62ef325a6acfc8ddcb43c8ae1c6 object 
CircuitInfoData_Deferred_circuit_bearer_circuit_cfb3d62ef325a6acfc8ddcb43c8ae1c6 object 
CircuitInfoData_Deferred_circuit_bearer_circuit_cfb3d62ef325a6acfc8ddcb43c8ae1c6 object 
... 

#### with either #### 

>>> for i in d: 
... print i.provider 
... 
BT 
BT 
KCOM 
BT 
BT 
KCOM 
... 

Answer 1

Die Dokumentation für distinct sagt

Returns a new QuerySet that uses SELECT DISTINCT in its SQL query. This eliminates duplicate rows from the query results.

By default, a QuerySet will not eliminate duplicate rows. In practice, this is rarely a problem, because simple queries such as Blog.objects.all() don’t introduce the possibility of duplicate result rows.

Distinct Sie verschiedene Reihen gibt, aber betrachten Sie nur eines der Felder im Datensatz und in diesem Feld können Elemente dupliziert werden, es sei denn, es hat eine eindeutige Einschränkung für sie. Und in diesem Fall nicht.

Wenn Sie postgresql passieren zu verwenden, können Sie tun

CircuitInfoData.objects.distinct('provider') 

Ihr Ziel zu erreichen.

UPDATE: Da Sie in den Kommentaren erwähnt, dass Sie SQLite verwenden, verwenden Sie diese Lösung.

Dies funktioniert, weil jetzt jede Zeile nur eine Spalte hat.

Beachten Sie, dass die __unicode__ Funktion außer Kraft gesetzt haben: die resultierende Abfrage wird

SELECT DISTINCT "someapp_circuitinfodata"."name" FROM "someapp_circuitinfodata" 

UPDATE 2 ähnlich sein.

def unicode (selbst): zurück '% s | % s | % s | % s | % S'% (self.showroom_config_data.location, self.major_site_info.location, self.provider, self.service_type, self.ref_no)

Sie sind in dem zugehörigen Modell auf die Felder verweisen. Dies wird sehr teuer (es sei denn, Sie verwenden select_related). Beachten Sie auch, dass Sie bei der Iteration eines Abfrage-Sets und der Verwendung von print zu Debug-Zwecken irreführende Ergebnisse erhalten (was Sie sehen, ist die Ausgabe von __unicode__, eine ziemlich komplexe Funktion)