【发布时间】：2021-11-01 17:18:38
【问题描述】：
我为我的 django 电子商务项目设计了一个数据库，但它有一些问题，目标是 这个设计是为了有不同规格的产品，比如一个手机有它自己的属性，一个电视也有， 这是我的models.py：
'''
from django.db import models
from mptt.models import MPTTModel, TreeForeignKey
from django.shortcuts import reverse
from model_utils import FieldTracker
from . import uploaders
class Category(MPTTModel):
name = models.CharField(max_length=50, unique=True)
parent = TreeForeignKey('self', on_delete=models.CASCADE, null=True, blank=True,
related_name='children')
slug = models.SlugField(max_length=75, unique=True)
tracker = FieldTracker(fields=['name'])
class MPTTMeta:
order_insertion_by = ['name']
def __str__(self):
category_names = [self.name]
node = self
while node.parent:
node = node.parent
category_names.append(node.name)
return ' / '.join(category_names[::-1])
def get_absolute_url(self):
return reverse('product_by_category', args=(self.slug,))
class ProductType(models.Model):
name = models.CharField(max_length=50, unique=True)
def __str__(self):
return self.name
class ProductSpecifications(models.Model):
name = models.CharField(max_length=50)
product_type = models.ForeignKey(ProductType, on_delete=models.CASCADE,
related_name='specifications')
class Meta:
unique_together = ('name', 'product_type')
def __str__(self):
return self.name
class Product(models.Model):
name = models.CharField(max_length=100, unique=True)
product_type = models.ForeignKey(ProductType, on_delete=models.CASCADE,
related_name='products')
category = models.ForeignKey(Category, on_delete=models.CASCADE,
related_name='products')
price = models.PositiveBigIntegerField()
discount_price = models.PositiveBigIntegerField(null=True, blank=True)
description = models.TextField(null=True, blank=True)
image = models.ImageField(upload_to=uploaders.product_img_uploader)
slug = models.SlugField(max_length=150, unique=True)
tracker = FieldTracker(fields=['slug', 'name', 'product_type'])
def __str__(self):
return self.name
def set_discount(self, percentage):
self.discount_price = self.price * (1 - percentage)
self.save()
@property
def is_discounted(self):
return bool(self.discount_price)
def remove_discount(self):
self.discount_price = None
self.save()
class ProductSpecificationValue(models.Model):
specification = models.ForeignKey(ProductSpecifications, on_delete=models.CASCADE)
product = models.ForeignKey(Product, on_delete=models.CASCADE,
related_name='specifications')
value = models.CharField(max_length=75, null=True, blank=True)
def __str__(self):
return ''
class Meta:
unique_together = ('specification', 'product')
'''
还有 admin.py：
'''
from django.contrib import admin
from django.http import HttpResponseRedirect
from mptt.admin import MPTTModelAdmin
from .models import *
from .forms import ProductSpecForm
@admin.register(Category)
class CategoryAdmin(MPTTModelAdmin):
readonly_fields = ('slug',)
class SpecificationInline(admin.TabularInline):
model = ProductSpecifications
extra = 2
@admin.register(ProductType)
class ProductTypeAdmin(admin.ModelAdmin):
inlines = (SpecificationInline,)
class SpecificationValueInline(admin.TabularInline):
model = ProductSpecificationValue
# form = ProductSpecForm
# fields = ('specification', 'value')
# readonly_fields = ('specification',)
#
# def has_add_permission(self, request, obj):
# return False
#
# def has_delete_permission(self, request, obj=None):
# return False
@admin.register(Product)
class ProductAdmin(admin.ModelAdmin):
inlines = (SpecificationValueInline,)
readonly_fields = ('slug',)
# def response_post_save_add(self, request, obj):
# return HttpResponseRedirect(
# reverse("admin:%s_%s_change" % (self.model._meta.app_label,
# self.model._meta.model_name), args=(obj.id,)))
'''
当您想添加或更改产品时，问题出在产品管理面板中，我希望 SpecificationValueInline 表单中的规范选择框只显示与产品类型相关的规范，而不是数据库中的所有规范，我在管理员中评论的行。带有一些信号和表格的py是我解决这个问题的方法我不知道这是否是最好的帮助我！
信号.py：
'''
from django.dispatch import receiver
from django.db.models.signals import pre_save, post_save
from .models import Category, Product, ProductSpecificationValue, ProductSpecifications
@receiver(pre_save, sender=Product)
@receiver(pre_save, sender=Category)
def initialize_slug(sender, instance, *args, **kwargs):
if (not instance.slug) or (instance.tracker.has_changed('name')):
instance.slug = instance.name.replace(' ', '_')
@receiver(post_save, sender=Product)
def initialize_specifications(sender, instance, created, **kwargs):
if created:
product_type = instance.product_type
for specification in product_type.specifications.all():
ProductSpecificationValue.objects.create(product=instance,
specification=specification)
elif instance.tracker.has_changed('product_type'):
ProductSpecificationValue.objects.filter(product=instance).delete()
product_type = instance.product_type
for specification in product_type.specifications.all():
ProductSpecificationValue.objects.create(product=instance,
specification=specification)
@receiver(post_save, sender=ProductSpecifications)
def add_new_specs_to_related_products(sender, instance, created, **kwargs):
if created:
product_type = instance.product_type
for product in product_type.products.all():
ProductSpecificationValue.objects.create(specification=instance,
product=product)
''' 表格.py： '''
from django import forms
from django.forms import ModelChoiceField
from .models import ProductSpecificationValue, Product
class ProductSpecForm(forms.ModelForm):
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
if hasattr(self.instance, 'product'):
self.fields['specification'] = ModelChoiceField(
queryset=self.instance.product.product_type.specifications.all())
class Meta:
model = ProductSpecificationValue
fields = ('specification', 'value')
'''
【问题讨论】：
标签： python django database e-commerce