错误auctions.models.Listing.DoesNotExist:列表匹配查询不存在。我刚开始学习django，我的代码有什么问题？

Question

这是我的views.py文件：

from django.contrib.auth import authenticate, login, logout
from django.contrib.auth.decorators import login_required
from django.db import IntegrityError
from django.http import HttpResponseRedirect
from django.shortcuts import render
from django.urls import reverse

from .models import *


def index(request):
    return render(request, "auctions/index.html", {
        "listings": Listing.objects.all()
    })


def login_view(request):
    if request.method == "POST":

        # Attempt to sign user in
        username = request.POST["username"]
        password = request.POST["password"]
        user = authenticate(request, username=username, password=password)

        # Check if authentication successful
        if user is not None:
            login(request, user)
            return HttpResponseRedirect(reverse("index"))
        else:
            return render(request, "auctions/login.html", {
                "message": "Invalid username and/or password."
            })
    else:
        return render(request, "auctions/login.html")


def logout_view(request):
    logout(request)
    return HttpResponseRedirect(reverse("index"))


def register(request):
    if request.method == "POST":
        username = request.POST["username"]
        email = request.POST["email"]

        # Ensure password matches confirmation
        password = request.POST["password"]
        confirmation = request.POST["confirmation"]
        if password != confirmation:
            return render(request, "auctions/register.html", {
                "message": "Passwords must match."
            })

        # Attempt to create new user
        try:
            user = User.objects.create_user(username, email, password)
            user.save()
        except IntegrityError:
            return render(request, "auctions/register.html", {
                "message": "Username already taken."
            })
        login(request, user)
        return HttpResponseRedirect(reverse("index"))
    else:
        return index(request)


@login_required(login_url='login')
def create(request):
    if request.method == "POST":
        title = request.POST["title"]
        description = request.POST["description"]
        price = request.POST["price"]
        picture = request.POST["picture"]
        user = User.objects.get(username=request.user)

        try:
            listing = Listing(item=title, description=description, price=price, image=picture, owner=user)
            listing.save()
        except IntegrityError:
            return render(request, "auctions/register.html", {
                "message": "Username already taken."
            })

        return index(request)
    else:
        return render(request, "auctions/new_listing.html")


@login_required(login_url='login')
def listing(request, listing):
    if request.method == "POST":
        bid = request.POST.get("bid")
        try:
            new_bid = listing.get_bids(time=time, user=request.user, price=bid)
            new_bid.save()
        except:
            return HttpResponseRedirect("ERROR")
        listing_info = Listing.objects.get(item=listing)
        return render(request, "auctions/listing.html", {
            "listing": listing_info
        })
    else:
        listing_info = Listing.objects.get(item=listing)
        return render(request, "auctions/listing.html", {
            "listing": listing_info
        })


@login_required(login_url='login')
def watchlist(request):
    user = User.objects.get(username=request.user)
    if request.method == "POST":
        product = request.POST.get("product")
        listing_info = Listing.objects.get(item=product)
        watch = Watchlist.objects.filter(product=listing_info, user=user)
        if not watch:
            try:
                new_product = Watchlist(user=user, product=listing_info)
                new_product.save()
            except:
                return render(request, "auctions/listing.html", {
                    "message": "ERROR."
                })
            return render(request, "auctions/listing.html", {
                "listing": listing_info,
                "message": "Added to watchlist",
                "collor": "green"
            })
        else:
            return render(request, "auctions/listing.html", {
                "listing": listing_info,
                "message": "Already in your watchlist",
                "collor": "red"
            })
    else:
        products = Watchlist.objects.filter(user=user)
        listing_dict = {}
        for product in products:
            listing_dict[product] = Listing.objects.get(item=product.product)
            return render(request, "auctions/watchlist.html", {
                "products": products,
                "info": listing_dict
            })

不是最好的，我本可以用更好的方式完成大部分工作，但这就是我所做的。这是我的Models.py代码：

from django.contrib.auth.models import AbstractUser
from django.db import models


class User(AbstractUser):
    pass


class Listing(models.Model):
    item = models.CharField(max_length=64)
    description = models.CharField(max_length=255, blank=True)
    price = models.DecimalField(max_digits=10, decimal_places=2)
    owner = models.ForeignKey(User, on_delete=models.CASCADE, related_name="owners")
    image = models.CharField(max_length=200)

    def __str__(self):
        return self.item


class Bid(models.Model):
    time = models.DateTimeField(auto_now_add=True, blank=True)
    user = models.ForeignKey(User, on_delete=models.CASCADE, related_name="user_bids")
    price = models.DecimalField(max_digits=10, decimal_places=2)
    product = models.ForeignKey(Listing, on_delete=models.CASCADE, related_name="product_bids")

    def __str__(self):
        return f"{self.user} put a bid in for {self.price}"


class Watchlist(models.Model):
    user = models.ForeignKey(User, on_delete=models.CASCADE, related_name="watchlist")
    product = models.ForeignKey(Listing, on_delete=models.CASCADE, related_name="products")

    def __str__(self):
        return f"{self.product} by {self.user}"

Answer 1

我不知道你发这个问题的时候是不是把代码弄错了，但是你的代码缩进得很厉害。您为User和Listing模型添加了两个制表符空间。我只是删除了一个制表符空格，并将其恢复为正常的缩进。

from django.contrib.auth.models import AbstractUser
from django.db import models
    
    
class User(AbstractUser):
    pass
    
    
class Listing(models.Model):
    item = models.CharField(max_length=64)
    description = models.CharField(max_length=255, blank=True)
    price = models.DecimalField(max_digits=10, decimal_places=2)
    owner = models.ForeignKey(User, on_delete=models.CASCADE, related_name="owners")
    image = models.CharField(max_length=200)
    
    def __str__(self):
        return self.item

class Bid(models.Model):
    time = models.DateTimeField(auto_now_add=True, blank=True)
    user =  models.ForeignKey(User, on_delete=models.CASCADE, related_name="user_bids")
    price = models.DecimalField(max_digits=10, decimal_places=2)
    product = models.ForeignKey(Listing, on_delete=models.CASCADE, related_name="product_bids")
    
    def __str__(self):
        return f"{self.user} put a bid in for {self.price}"

...

Answer 2

我按原样复制了您的整个代码，到目前为止没有任何错误。

你试过跑步吗？

python manage.py makemigrations auctions

然后

python manage.py migrate

然后返回到

python manage.py runserver