django 管理数据未在数据库中注册

Question

I am building an ecommerce website with Django and having some difficulties to transfer data from the admin page to the database and then html. I am new to Django and I would love your help. I added 7 "products" (class Product) via Django admin page.

models.py

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


class Customer(models.Model):
    user = models.OneToOneField(User, on_delete=models.CASCADE, null=True, blank=True)
    name = models.CharField(max_length=200, null=True)
    email = models.CharField(max_length=200, null=True)

    def __str__(self):
        return self.name


class Product(models.Model):
    name = models.CharField(max_length=200)
    price = models.FloatField()
    
    def __str__(self):
        return self.name


class Order(models.Model):
    customer = models.ForeignKey(Customer, on_delete=models.SET_NULL, null=True, blank=True)
    date_ordered = models.DateTimeField(auto_now_add=True)
    complete = models.BooleanField(default=False)
    transaction_id = models.CharField(max_length=100, null=True)

    def __str__(self):
        return str(self.id)


class OrderItem(models.Model):
    product = models.ForeignKey(Product, on_delete=models.SET_NULL, null=True)
    order = models.ForeignKey(Order, on_delete=models.SET_NULL, null=True)
    quantity = models.IntegerField(default=0, null=True, blank=True)
    date_added = models.DateTimeField(auto_now_add=True)


class ShippingAddress(models.Model):
    customer = models.ForeignKey(Customer, on_delete=models.SET_NULL, null=True)
    order = models.ForeignKey(Order, on_delete=models.SET_NULL, null=True)
    address = models.CharField(max_length=200, null=False)
    city = models.CharField(max_length=100, null=False)
    country = models.CharField(max_length=100, null=False)
    postcode = models.CharField(max_length=100, null=False)
    date_added = models.DateTimeField(auto_now_add=True)

    def __str__(self):
        return self.address

views.py

from django.shortcuts import render
from .models import *


def products(request):
    products = Product.objects.all()
    context = {'products':products}
    return render(request, 'store/products.html')


def cart(request):
    context = {}
    return render(request, 'store/cart.html')


def checkout(request):
    context = {}
    return render(request, 'store/checkout.html')


def home(request):
    context = {}
    return render(request, 'store/home.html')

admin.py

from django.contrib import admin
from .models import *

admin.site.register(Customer)
admin.site.register(Product)
admin.site.register(Order)
admin.site.register(OrderItem)
admin.site.register(ShippingAddress)

In settings.py, the default database is sqlite3

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': BASE_DIR / 'db.sqlite3',
    }
}

Screen shot of Django admin page with products successfully added

I have done the migrations and the database db.sqlite3 exits in my project folder.

However, when I check the values of the table "store_product", it seems empty...

prompt

SQLite version 3.33.0 2020-08-14 13:23:32
Enter ".help" for usage hints.
sqlite> .width
sqlite> .mode markdown
sqlite> select * from store_product
   ...>

In my html page where I want to display the products, nothing displays... The variable products is empty:

products.html

        {% if products is defined %}
            value of variable: {{ products }}
        {% else %}
            variable is not defined
        {% endif %}

it displays nothing...

Thanks a lot for your help.

Answer 1

You never pass the context to your view. It should be like:

def products(request):
    products = Product.objects.all()
    context = {'products':products}
    return render(request, 'store/products.html', context)

Also that {% if products is defined %} would not make any sense. So simply render the products:

{% for product in products %}
    Product: {{ product.name }}
    Price: {{ product.price }}
{% empty %}
    No products to display!
{% endfor %}

Answer 2

Your template code looks wrong - is defined is not python.

The following is sufficient:

{% if products %}
<ul>
    {% for product in products %}
    <li>{{ product.name }}: {{ product.price }}
    {% endfor %}
</ul>
{% else %}
    No products.
{% endif %}

The Django Admin shows exactly whatever is in its connected database, there is no cache.

If you cannot see the data in the sqlite client or your other view, this makes me suspect that you are not using the same database or that the sqlite lost the data in the meanwhile (deleting the file will recreate it the next time you start your local server, and the data will be lost).

You might want to start using the DB you are planning to use in production, to rule these issues out, and to be closer to your production setup when developing.