I'm working on a Django project that uses models. I want to somehow access the highest bid on that listing at all times (as listing.highest_bid) or some other way if there's a better solution. What I tried in the code snippet below for the highest_bid doesn't seem to work, it gives me an AttributeError (AttributeError: 'str' object has no attribute 'bids'). How can I access a model's own parameter's values and filter them to my liking?
class Listing(models.Model):
user = models.ForeignKey(User, on_delete=models.CASCADE, related_name="listings")
title = models.CharField(max_length=100)
description = models.CharField(max_length=1000)
starting_bid = models.PositiveIntegerField()
picture = models.TextField(max_length=200, default='static/auctions/notfound.png')
category = models.ForeignKey(Category, on_delete=models.CASCADE,related_name="listings")
is_active = models.BooleanField()
highest_bid = self.bids.aggregate(Max('price'))
def __str__(self):
return f"{self.title}"
class Bid(models.Model):
listing = models.ForeignKey(Listing, on_delete=models.CASCADE, related_name="bids")
user = models.ForeignKey(User, on_delete=models.CASCADE, related_name="bids")
price = models.PositiveIntegerField()
# time TODO
def __str__(self) -> str:
return f"Bid #{self.id}"
You can simply use @property to return a such as computed field
class Listing(models.Model):
# Some fields
@property
def highest_bid(self):
# Access the Listing bids by reverse foreign key and retrieve the first with highest price
return self.bids.order_by('-price').first()
Note : Each time you do listing.highest_bid the function will be executed to return the result (Dynamic)