Python 基于特定类别名称筛选对象
我正在尝试筛选所有类别名称为“Books”的产品。请看下面我尝试过的内容,但我得到的查询集是空的 这是我的Python 基于特定类别名称筛选对象,python,django,Python,Django,我正在尝试筛选所有类别名称为“Books”的产品。请看下面我尝试过的内容,但我得到的查询集是空的 这是我的models.py以防万一: from django.db import models from django.urls import reverse [...] class Product(models.Model): title = models.CharField(max_length=200) description = models.TextFiel
models.py
以防万一:
from django.db import models
from django.urls import reverse
[...]
class Product(models.Model):
title = models.CharField(max_length=200)
description = models.TextField()
price = models.DecimalField(decimal_places=2, max_digits=10)
year = models.PositiveSmallIntegerField()
image = models.ImageField(upload_to=get_image_path, blank=True, null=True)
date_added = models.DateTimeField(auto_now=True, null=True)
category = models.ForeignKey('Category', on_delete=models.CASCADE)
[...]
class Category(models.Model):
parent = models.ForeignKey('self', null=True, blank=True, on_delete=models.CASCADE)
name = models.CharField(max_length=255)
def __str__(self):
return self.name
我试过这个:
>>> from products.models import Product, Category
>>> c = Category(name='Books')
>>> c1 = Category(name='Textbooks', parent=c)
>>> c2 = Category(name='Primary school', parent=c1)
>>> p = Product(title='spam', description='spameggs', price=200, year=2018, category=c2)
>>> for x in (c, c1, c2, p):
... x.save()
...
>>> Product.objects.get(category=c2)
<Product: Product object (1)>
>>> Product.objects.filter(category__name='Books')
<QuerySet []>
>>> Product.objects.filter(Q(category__name='Books') | Q(category__parent__name='Books') | Q(category__parent__parent__name="Books"))
<QuerySet []>
>>来自products.models导入产品,类别
>>>c=类别(名称=书籍)
>>>c1=类别(名称=,父类=c)
>>>c2=类别(名称=小学,家长=c1)
>>>p=产品(标题='spam',说明='spameggs',价格=200,年份=2018,类别=c2)
>>>对于x in(c,c1,c2,p):
... x、 保存()
...
>>>Product.objects.get(category=c2)
>>>Product.objects.filter(category\uu name='Books')
>>>Product.objects.filter(Q(category_uname='Books')|Q(category_uparent_uname='Books')|Q(category_uparent_uparent_uname='Books)))
使用数据库工具检查数据库后,我意识到类别
外键为空
。问题是我在保存父项之前分配了父项,这意味着它们没有PrimaryKey,因此ForeignKey被设置为NULL