如何解决无法分配“''”：“ IncomeExpense.username”必须是“ User”实例
我正在处理以下代码，尝试通过从表单获取值将数据添加到表中。我还用v_id标记了哪里出错了。
我在下面粘贴了#，views.py和models.py。可能是我收到此错误的原因，并且还向我解释了可以更改以消除此错误的原因。
createentry.html#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>
此外，为什么我会收到错误消息#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)
，如果更改某些内容，我还会得到另一个类似的错误消息。
我尝试在此方法内将用户名更改为Cannot assign "''": "IncomeExpense.username" must be a "User" instance.：
username__username解决方法
我们在这里使用username字段来保存user id，但是您通过了username。
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")
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