我正在努力使用 Django 模板语言在 for 循环中创建一个 if 条件。CS50w 项目2

问：

在此处查看我的代码 https://gist.github.com/Schultzy11/d93bc34d13adc1263337604c44827147

我有一个带有“listings”变量的for循环，可以对其进行索引以创建我想要的值。

但是当我尝试使用 top_bids 变量创建一个 if 条件并使用 .listings.id 索引到其中时，它并没有给我预期的结果。

供参考 当我打印 top_bids 变量时，我得到 .{1: 700.0, 2: None}

我希望得到：第一篇文章显示最高出价：700 美元，第二篇显示起价 10000 美元

这是我目前得到的

我现在得到的截图

html.py

{% extends "auctions/layout.html" %}

{% block body %}
    <h2>Active Listings</h2>
    <div class="container">
    
    {% for listing in listings %}
    <div class="card mb-3 mt-4">
        <div class="row g-0 align-items-center">
            <div class="col-md-4" style="max-width: 300px; max-height: 300px;">
                <img src="{{listing.image_url}}" class="img-fluid rounded-start" alt="{{listing.title}}">
            </div>
            <div class="col-md-8 ">
                <div class="card-body">
                    <h3 class="card-title">{{listing.title}}</h3>
                    <p class="card-text">{{listing.description}}</p>

                    {% if top_bids.listing.id == None %}
                    <p class="card-text">Start Price: ${{listing.start_bid}}</p>
                   
                    {% else %}
                    <p class="card-text">Top Bid: ${{ top_bids.listing.id }}</p>
                    {% endif %}
                

                    <p class="card-text"><small class="text-body-secondary">Created: {{listing.date_created}}</small></p>
                    <div class="mt-4">
                        <a href=""><button class="btn btn-primary">View</button></a>
                    </div>
                </div>
            </div>
        </div>
    </div>
    {% endfor %}
    </div>
{% endblock %}

models.py

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


class User(AbstractUser):
    pass

class Listings(models.Model):
    title = models.CharField(max_length=50)
    description = models.TextField()
    start_bid = models.FloatField()
    image_url = models.URLField(blank=True, null=True)
    category = models.ForeignKey("Categories", on_delete=models.PROTECT)
    date_created = models.DateTimeField(auto_now_add=True)

    def __str__(self):
        return f"{self.id}: {self.title} starting at {self.start_bid} in {self.category} on {self.date_created}"

class ListingsOwned(models.Model):
    user = models.ForeignKey("User", on_delete=models.CASCADE)
    listing = models.ForeignKey("Listings", on_delete=models.CASCADE)


class Bids(models.Model):
    user = models.ForeignKey("User", on_delete=models.CASCADE)
    listing = models.ForeignKey("Listings", on_delete=models.CASCADE)
    amount = models.FloatField()

    def __str__(self):
        return f"{self.user} bid {self.amount} on {self.listing.title}"


class Comments(models.Model):
    user = models.ForeignKey("User", on_delete=models.CASCADE)
    listing = models.ForeignKey("Listings", on_delete=models.CASCADE)
    comment = models.TextField()

class Categories(models.Model):
    category = models.CharField(max_length=40)
    def __str__(self):
        return f"{self.category}"

views.py

from django import forms
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 HttpResponse, HttpResponseRedirect
from django.shortcuts import render
from django.urls import reverse

from .models import User, Categories, Listings, Bids


class NewListing(forms.Form):
    title = forms.CharField(max_length=50, label="Title", required=True)
    description = forms.CharField(required=True, label="Description")
    start_bid = forms.FloatField(required=True, label="Starting Bid")
    image_url = forms.URLField(required=False, label="Image URL" )
    category = forms.ModelChoiceField(queryset=Categories.objects.all())


def index(request):
    # get all listing information
    listings = Listings.objects.all()

    # get list of ids
    ids = Listings.objects.all().values('id')
    # initiate top bids dict
    top_bids={}
    # loop to check for top bids else set None
    for row in ids:
    # check there are bids
        listing_id = row['id']
        try:
            top_bid = Bids.objects.filter(listing = listing_id).order_by("-amount")[0]
            top_bid = top_bid.amount
            top_bids[listing_id] = top_bid
        except IndexError:
            top_bids[listing_id] = None
    
    print(top_bids)

    return render(request, "auctions/index.html", {
        "listings": listings, "top_bids": top_bids    
    })