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我想寫一個Django查詢來查找一組父記錄與某些種類的子記錄。問題是帶有兩個匹配搜索子項的父記錄將包含兩次結果。Django查詢子記錄沒有得到重複的行
即使有多個匹配的孩子，我如何才能讓每個父母都有一次？
我已經在下面包含了一個簡單的例子來演示這個問題。 Blog是父母，Entry是孩子。當我在標題中搜索包含「Hello」的條目的博客時，我會收到Jimmy博客的兩份副本。
下面是我創建的記錄和查詢我想：
b = Blog(name="Jimmy's Jottings")
b.save()
Entry(blog=b, headline='Hello, World!').save()
Entry(blog=b, headline='Hello Kitty').save()
blog_count = Blog.objects.filter(entries__headline__contains='Hello').count()
assert blog_count == 1, blog_count
你可以看到，只有一個博客，但斷言失敗的兩個計數。
下面是完整的例子：
# Tested with Django 1.9.2
import sys
import django
from django.apps import apps
from django.apps.config import AppConfig
from django.conf import settings
from django.db import connections, models, DEFAULT_DB_ALIAS
from django.db.models.base import ModelBase
NAME = 'udjango'
def main():
setup()
class Blog(models.Model):
name = models.CharField(max_length=100)
tagline = models.TextField()
def __str__(self): # __unicode__ on Python 2
return self.name
class Entry(models.Model):
blog = models.ForeignKey(Blog, related_name='entries')
headline = models.CharField(max_length=255)
body_text = models.TextField()
def __str__(self): # __unicode__ on Python 2
return self.headline
syncdb(Blog)
syncdb(Entry)
b = Blog(name="Jimmy's Jottings")
b.save()
Entry(blog=b, headline='Hello, World!').save()
Entry(blog=b, headline='Hello Kitty').save()
blog_count = Blog.objects.filter(entries__headline__contains='Hello').count()
assert blog_count == 1, blog_count
print('Done.')
def setup():
DB_FILE = NAME + '.db'
with open(DB_FILE, 'w'):
pass # wipe the database
settings.configure(
DEBUG=True,
DATABASES={
DEFAULT_DB_ALIAS: {
'ENGINE': 'django.db.backends.sqlite3',
'NAME': DB_FILE}},
LOGGING={'version': 1,
'disable_existing_loggers': False,
'formatters': {
'debug': {
'format': '%(asctime)s[%(levelname)s]'
'%(name)s.%(funcName)s(): %(message)s',
'datefmt': '%Y-%m-%d %H:%M:%S'}},
'handlers': {
'console': {
'level': 'DEBUG',
'class': 'logging.StreamHandler',
'formatter': 'debug'}},
'root': {
'handlers': ['console'],
'level': 'WARN'},
'loggers': {
"django.db": {"level": "WARN"}}})
app_config = AppConfig(NAME, sys.modules['__main__'])
apps.populate([app_config])
django.setup()
original_new_func = ModelBase.__new__
@staticmethod
def patched_new(cls, name, bases, attrs):
if 'Meta' not in attrs:
class Meta:
app_label = NAME
attrs['Meta'] = Meta
return original_new_func(cls, name, bases, attrs)
ModelBase.__new__ = patched_new
def syncdb(model):
""" Standard syncdb expects models to be in reliable locations.
Based on https://github.com/django/django/blob/1.9.3
/django/core/management/commands/migrate.py#L285
"""
connection = connections[DEFAULT_DB_ALIAS]
with connection.schema_editor() as editor:
editor.create_model(model)
main()