钱包交易后如何更改用户和产品（型号）的价值

Question

Here is my model.py, where Customer is the one to make orders and purchase products.

class Customer(models.Model):
    user = models.OneToOneField(User, null=True, blank=True, on_delete=models.CASCADE)
    name = models.CharField(max_length=25, null=True)
    phone = models.CharField(max_length=12, null=True)

    def __str__(self):
        return self.name

class Product(models.Model):
    user = models.ForeignKey(User, on_delete=models.CASCADE)
    coinid = models.CharField(max_length=255, null=True)
    digit = models.CharField(max_length=18, null=True)
    ctp = models.FloatField(max_length=100, null=True)
    transection_id = models.IntegerField(null=True, default=0)
    slug = models.SlugField(max_length=250, null=True, blank=True)
    date_created = models.DateField(auto_now_add=True, null=True)

    def __str__(self):
        return self.coinid

    def get_absolute_url(self):
        return reverse("core:detail", kwargs={
        'slug': self.coinid
        })

class Balance(models.Model):
    user = models.ForeignKey(User, on_delete=models.CASCADE)
    balance = models.IntegerField(default=0)

    def __str__(self):
        return self.user.username

In views.py, Here I want to replace the user (Product.user) of the product by sender sending amount from wallet.

def buy_c(request, ok):
    ctp_val = Product.objects.get(id=ok)
    msg = "Enter Details"
    if request.method == "POST":
        try:
            username = request.POST["username"]
            amount = request.POST["amount"]
            senderUser = User.objects.get(username=request.user.username)
            receiverrUser = User.objects.get(username=username)
            sender = Balance.objects.get(user=senderUser)
            receiverr = Balance.objects.get(user=receiverrUser)
            sender.balance = sender.balance - float(amount)
            receiverr.balance = receiverr.balance + float(amount) 
            
            if senderUser == receiverrUser:
                return Exception.with_traceback()
            else:
                sender.save()
                receiverr.save()
                msg = "Transaction Success"
                return redirect("/user")
    
        except Exception as e:
            print(e)
            msg = "Transaction Failure, Please check and try again"
    
    context = {"coin": ctp_val, "msg":msg}
    return render(request, 'coinwall.html', context)

Here is my template coinwall.html:

<tr>
    <th>username</th>
    <th>Coin Id</th>
    <th>current CTP</th>
    <th>Total Transections</th>
</tr>

<tr>
    <td>{{coin.user}}</td>
    <td>{{coin.coinid}}</td>
    <td>{{coin.ctp}}</td>
    <td>{{coin.transection_id}}</td>
</tr>

{% if msg %}
<br><br>
{{msg}}
{% endif %}
<form method="POST">
    <input type="text" name="username" value="{{coin.user}}" readonly><br><br>

    <input type="text" name="amount" value="{{coin.ctp}}" readonly><br><br>
    <input type="submit" value="Submit">
    {% csrf_token %}
</form>

Also it will be great if someone can tell me how the admin can trace the transactions and restrict the user if out of Balance.

Answer 1

in views.py, Here I want to replace the user(Product.user) of the product by sender sending amount from wallet

ctp_val.update(user=receiverrUser)

Also, it will be great if someone can (a) tell me how the admin can trace the transactions and (b) restrict the user If out of Balance. Thank you <3

(a) You will need to create a new table Transaction that will keep track of the exchange between users. Something like (pseudo-Django-Python code):

class Transaction:
    id = random_generated_hash()
    timestamp = time.now()

    buyer = User
    seller = User
    product = Product
    price = float

And then on every transaction, create a new Transaction entry. You can then either (1) keep track of transactions via the Django admin portal, or (2) create an new admin-only page that shows all of the transactions.

(b)

recvbalance = Balance.objects.filter(user=receiverrUser).first()

if recvbalance and recvbalance.balance >= ctp_val.price: # Whatever is the key for 'product price'.
    # Do exchange here.
else:
    # Throw error.

Answer 2

thank you @Felipe, I did tried,

ctp_val.update(user=receiverrUser)

Product value has to attribute 'update'

then I tried;

ctp_val.user = senderUser
                ctp_val.save()

and it worked for me

In (a) I want to know, how I can get recent data/transection details between users. thank you for (b)<3