Cannot assign "''": "IncomeExpense.username" must be a "User" instance - python-3.x

Question

I am working on this below code, trying the add data to the table by getting the values from the form. I have also marked where I am getting the error with #.
I have pasted views.py, models.py and createentry.html below. What might be the reason why I am getting this error and also explain me what I can change to get rid of this error.
#views.py
def create_entry_form(request):
if request.method=='POST':
entry_type=request.POST.get("expensetype")
amount=request.POST.get("amount")
details=request.POST.get("entrydetails")
capture_date=time.strftime('%Y-%m-%d')
entry_username=request.POST.get("entryusername")
entry=IncomeExpense.objects.create(entry_type=entry_type, amount=amount, details=details, capture_date=capture_date, username=entry_username) #getting_error_in_this_line
entry.save()
user_balance = UserBalance.objects.filter(username=username).values_list('balance', flat=True)[0]
if entry_type=="income":
total_balance = user_balance + amount
else:
total_balance=user_balance - amount
update_balance=UserBalance.objects.get(username=username)
update_balance.value=total_balance
update_balance.save()
return render(request, "homepage.html", {'name':username, 'balance':total_balance})
else:
return redirect("www.google.com")
<!---- createentry.html ---->
<form action="{% url 'create_entry_form' %}" method="post">
{% csrf_token %}
<div class="container register-form">
<div class="form">
<div class="note">
<p>Create Entry Form</p>
</div>
<div class="form-content">
<div class="row">
<div class="col-md-6">
<div class="form-group">
<select name="expensetype" id="expensetype" class="form-control">
<option value="expensetype">Select Expense Type</option>
<option value="income">income</option>
<option value="expense">expense</option>
</select>
</div>
<div class="form-group">
<input type="text" name="amount" id="amount" class="form-control" placeholder="Enter the Amount" value=""/>
</div>
</div>
<div class="col-md-6">
<div class="form-group">
<input type="text" name="entrydetails" id="entrydetails" class="form-control" placeholder="Enter the entry details" value=""/>
</div>
<div class="form-group">
<input type="text" name="entryusername" id="entryusername" class="form-control" placeholder="{{name}}" value=""/>
</div>
</div>
</div>
<button type="submit" class="btnSubmit">Submit</button>
</div>
</div>
</div>
</form>
#models.py
from django.db import models
from django.contrib.auth.models import User
class IncomeExpense(models.Model):
entry_type=models.CharField(max_length=100)
amount=models.IntegerField()
details=models.TextField()
capture_date=models.DateField()
username=models.ForeignKey(User, on_delete=models.CASCADE)
def __str__(self):
return f"{self.id}"
class UserBalance(models.Model):
balance=models.IntegerField()
username=models.ForeignKey(User, on_delete=models.CASCADE)
Also, why am I getting an error Cannot assign "''": "IncomeExpense.username" must be a "User" instance. and if I change something I get another similar one.
I tried changing the username to username__username inside this method:
entry=IncomeExpense.objects.create(entry_type=entry_type, amount=amount, details=details, capture_date=capture_date, username=entry_username)

Answer 1

Here we use username field to save user id but you pass username.That is wrong.
def create_entry_form(request):
if request.method=='POST':
entry_type=request.POST.get("expensetype")
amount=request.POST.get("amount")
details=request.POST.get("entrydetails")
capture_date=time.strftime('%Y-%m-%d')
entry_username=request.POST.get("entryusername")
entry=IncomeExpense.objects.create(entry_type=entry_type, amount=amount, details=details, capture_date=capture_date, username=request.user) #getting_error_in_this_line
entry.save()
user_balance = UserBalance.objects.filter(username=request.user).values_list('balance', flat=True)[0]
if entry_type=="income":
total_balance = user_balance + amount
else:
total_balance=user_balance - amount
update_balance=UserBalance.objects.get(username=request.user)
update_balance.balance=total_balance
update_balance.save()
return render(request, "homepage.html", {'name':request.user, 'balance':total_balance})
else:
return redirect("www.google.com")