[英]Accessing other model field when validating model field in Django
所以我有一個 Django 拍賣應用程序,它有 4 個模型:用戶、列表、投標、評論。
當用戶嘗試對某個列表出價時,我想檢查Bid
model 中的bid_amount
字段是否小於Listing
model 中的starting_bid
字段。
另外,我想問一下,這種東西的最佳做法是什么? AFAIK,您可以驗證forms.py
中的表單字段。
謝謝!
模型.py
class Listing(models.Model):
"""Auction listing"""
user = models.ForeignKey(User, verbose_name='user owner', on_delete=models.CASCADE, related_name="usr_listings")
title = models.CharField(max_length=64)
description = models.TextField(max_length=160)
starting_bid = models.PositiveIntegerField()
bids_number = models.PositiveIntegerField(default=1)
img_url = models.URLField("Image URL", max_length=200, blank=True)
category = models.CharField(max_length=64, blank=True)
date_listed = models.DateTimeField(default=timezone.now)
class Meta:
verbose_name = 'auction listing'
ordering = ['-date_listed']
def __str__(self):
return self.title
def get_absolute_url(self):
print('loading... get_absolute_url')
return reverse('listing_detail', kwargs={'pk': self.pk})
class Bid(models.Model):
"""Bids made on auction listing"""
listing = models.ForeignKey(Listing, on_delete=models.CASCADE, related_name="listing_bids")
user = models.ForeignKey(User, on_delete=models.CASCADE, related_name="user_bidder")
bid_amount = models.PositiveIntegerField(default=None)
class Meta:
verbose_name = 'Bid'
def __str__(self):
return f'{self.bid_amount} by {self.user} on {self.listing}'
def clean(self):
super().clean()
# do something to access Listing.starting bid, and Listing.user
將此添加到Bid
的clean
方法為您解決問題。
from django.core.exceptions import ValidationError
...
if self.bid_amount < self.listing.starting_bid:
raise ValidationError("bid_amount must be greater than or equal to starting_bid of the listing")
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