Decrement model value in django
It's my first time using django to clear my schoolwork, I want to lower Stock in my Book class by Quantity value, ex. Stock = 10 and Quantity = 1 Stock = 9 because 10 - 1 for Stock - Quantity this is my code
main.html
{% load static %}
<html>
<head>
<title>
Bookstore Management System
</title>
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.5.0/css/bootstrap.min.css" integrity="sha384-9aIt2nRpC12Uk9gS9baDl411NQApFmC26EwAOH8WgZl5MYYxFfc+NcPb1dKGj7Sk" crossorigin="anonymous">
</head>
<body>
{% include 'book/navbar.html' %}
{% block content %}
{% endblock %}
<br>
<script src="https://code.jquery.com/jquery-3.5.1.slim.min.js" integrity="sha384-DfXdz2htPH0lsSSs5nCTpuj/zy4C+OGpamoFVy38MVBnE+IbbVYUew+OrCXaRkfj" crossorigin="anonymous"></script>
<script src="https://cdn.jsdelivr.net/npm/popper.js@1.16.0/dist/umd/popper.min.js" integrity="sha384-Q6E9RHvbIyZFJoft+2mJbHaEWldlvI9IOYy5n3zV9zzTtmI3UksdQRVvoxMfooAo" crossorigin="anonymous"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.5.0/js/bootstrap.min.js" integrity="sha384-OgVRvuATP1z7JjHLkuOU7Xw704+h835Lr+6QL9UvYjZE3Ipu6Tp75j7Bh/kR0JKI" crossorigin="anonymous"></script>
</body>
</html>
home.html
{% extends 'book/main.html' %}
{% block content %}
<br>
<div class="container jumbotron">
<div class="container row">
<div class="col-lg-10">
<table class="table table-sm">
<tr>
<th>title</th>
<th>Author</th>
<th>Edition</th>
<th>Stock</th>
<th>Price</th>
</tr>
{% for book in books %}
<tr>
<td>{{book.title}}</td>
<td>{{book.Author}}</td>
<td>{{book.Edition}}</td>
<td>{{book.Stock}}</td>
<td>{{book.Price}}</td>
<td><a class="btn btn-sm btn-info" href="{% url 'addtocart' book.id %}">Add to cart</a></td>
</tr>
{% endfor %}
</table>
</div>
</div>
</div>
{% endblock %}
viewcart.html
{% extends 'book/ma开发者_JS百科in.html' %}
{% load static %}
{% block content %}
<div class="container">
<div class="row">
<div class="col-lg-10"></div>
<br>
<h5>BOOKS:</h5>
<div class="card card-body">
<table>
<tr>
<th>title</th>
<th>Author</th>
<th>Edition</th>
<th>Quantity</th>
<th>Price</th>
<th>Total</th>
</tr>
{% for book in cart.books.all %}
<tr>
<td>{{book.title}}</td>
<td>{{book.Author}}</td>
<td>{{book.Edition}}</td>
<td>{{book.Quantity}}</td>
<td>{{book.Price}}</td>
<td>{{book.Total}}</td>
</tr>
{% endfor %}
</table>
</div>
</div>
</div>
{% endblock %}
Model.py
from django.db import models
from django.db.models import F
from django.contrib.auth.models import User
class Book(models.Model):
title=models.CharField(max_length=300, null=True)
Author=models.CharField(max_length=300, null=True)
Edition=models.IntegerField()
Price=models.IntegerField()
Stock=models.IntegerField()
Quantity=models.IntegerField()
Total=models.IntegerField()
def decrementStock(self):
self.Quantity += 1
self.update(Stock=F('Stock') - F('Quantity'))
self.save()
def Tprice(self):
self.update(Total=F('Price') * F('Quantity'))
self.save()
def _str_(self):
return str(self.title)
class Customer(models.Model):
user=models.OneToOneField(User, null=True, on_delete=models.CASCADE)
name=models.CharField(max_length=200, null=True)
phone=models.CharField(max_length=200, null=True)
email=models.CharField(max_length=200, null=True)
date_created=models.DateTimeField(auto_now_add=True, null=True)
def _str_ (self):
return str(self.name)
class Cart(models.Model):
customer=models.OneToOneField(Customer, null=True, on_delete=models.CASCADE)
books=models.ManyToManyField(Book)
def _str_ (self):
return str(self.customer)
views.py
from django.shortcuts import render, redirect
from django.http import HttpResponse
from .models import *
from django.contrib.auth import login,logout,authenticate
from .forms import *
def home(request):
books=Book.objects.all()
context={'books':books}
if request.user.is_staff:
return render(request, 'book/adminhome.html', context)
else:
return render(request, 'book/home.html', context)
def logoutPage(request):
logout(request)
return redirect('/')
def loginPage(request):
if request.user.is_authenticated:
return redirect('home')
else:
if request.method=="POST":
username=request.POST.get('username')
password=request.POST.get('password')
user=authenticate(request,username=username, password=password)
if user is not None:
print("working")
login(request,user)
return redirect('/')
context ={}
return render(request,'book/login.html',context)
def registerPage(request):
if request.user.is_authenticated:
return redirect('home')
else:
form=createuserform()
cust_form=createcustomerform()
if request.method=='POST':
form=createuserform(request.POST)
cust_form=createcustomerform(request.POST)
if form.is_valid() and cust_form.is_valid:
user=form.save()
customer=cust_form.save(commit=False)
customer.user=user
customer.save()
return redirect('login')
context={
'form':form,
'cust_form':cust_form
}
return render(request,'book/register.html', context)
def addbook(request):
form=createbookform()
if request.method=='POST':
form=createbookform(request.POST)
if form.is_valid():
form.save()
return redirect('/')
context={'form':form}
return render(request,'book.addbook.html', context)
def viewcart(request):
cust=Customer.objects.filter(user=request.user)
for c in cust:
carts=Cart.objects.all()
for cart in carts:
if(cart.customer==c):
context={
'cart':cart
}
return render(request, 'book/viewcart.html', context)
else:
return render(request,'book/emptycart.html')
def addtocart(request,pk):
book=Book.objects.get(id=pk)
Book.objects.get(Quantity=pk).decrementStock()
cust=Customer.objects.filter(user=request.user)
for c in cust:
carts=Cart.objects.all()
reqcart=''
for cart in carts:
if(cart.customer==c):
reqcart=cart
break
if(reqcart==''):
reqcart=Cart.objects.create(
customer=c,
)
reqcart.books.add(book)
return redirect('/')
in model.py and views.py are wrong but i dont know to fix it sorry for my bad english writing and i thank you for poeple to helped me.
I try by editing model.py by using this but its failed and get these error `
Environment:
Request Method: GET
Request URL: http://127.0.0.1:8000/addtocart/1
Django Version: 3.2
Python Version: 3.10.7
Installed Applications:
['django.contrib.admin',
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.messages',
'django.contrib.staticfiles',
'book']
Installed Middleware:
['django.middleware.security.SecurityMiddleware',
'django.contrib.sessions.middleware.SessionMiddleware',
'django.middleware.common.CommonMiddleware',
'django.middleware.csrf.CsrfViewMiddleware',
'django.contrib.auth.middleware.AuthenticationMiddleware',
'django.contrib.messages.middleware.MessageMiddleware',
'django.middleware.clickjacking.XFrameOptionsMiddleware']
Traceback (most recent call last):
File "C:\coding python\MHB\lib\site-packages\django\core\handlers\exception.py", line 47, in inner
response = get_response(request)
File "C:\coding python\MHB\lib\site-packages\django\core\handlers\base.py", line 181, in _get_response
response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "C:\coding python\MHB\Scripts\bookstore\book\views.py", line 80, in addtocart
Book.objects.get(Quantity=pk).decrementStock()
File "C:\coding python\MHB\lib\site-packages\django\db\models\manager.py", line 85, in manager_method
return getattr(self.get_queryset(), name)(*args, **kwargs)
File "C:\coding python\MHB\lib\site-packages\django\db\models\query.py", line 435, in get
raise self.model.DoesNotExist(
Exception Type: DoesNotExist at /addtocart/1
Exception Value: Book matching query does not exist.
`
加载中,请稍侯......
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