“类型为'NoneType'的对象没有len()"错误 [英] “object of type 'NoneType' has no len()” error
问题描述
错误:"NoneType"类型的对象没有len()Django的Signupform验证错误
Error: object of type 'NoneType' has no len() Error in Signupform validation in django
def signup(request):
print(request)
if request.method == "POST":
error_msg = None
fname = request.POST.get('fname')
lname = request.POST.get('lname')
email = request.POST.get('email')
password = request.POST.get('password')
value = {'fname': fname,
'lname': lname,
'email':email}
customer = Signup(first_name=fname, last_name=lname,
email=email, password=password)
if len(fname) < 4:
error_msg = "First Name Must Be More Than 4 Character"
elif len(lname) < 4:
error_msg = "Last Name Must Be More Than 4 Character"
elif customer.is_exist(): # describe in models.py
error_msg = "Email is Registered"
if not error_msg:
customer.save()
return redirect('index')
else:
context = {'error': error_msg, 'value':value}
return render(request, 'product/signup.html', context)
else:
print('get request')
return render(request, 'product/signup.html')
models.py:
models.py :
class Signup(models.Model):
first_name=models.CharField(max_length=100)
last_name=models.CharField(max_length=100)
email = models.EmailField()
password = models.CharField(max_length=500)
def __str__(self):
return self.first_name
def is_exist(self):
return Signup.objects.filter(email = self.email)
GET请求还传递了一个值(变量),我没有在get请求中传递任何变量
GET request also pass a Value(variable) I didn't pass any variable in get request
推荐答案
您的 fname,lname
从 request.POST.get('fname'),request.POST.get(如果将相应的字段提交为空,则'lname')
将得到一个 None
对象,因此, len(None)
将引发 TypeError:类型的对象'NoneType'没有len()
Your fname, lname
derived from request.POST.get('fname'), request.POST.get('lname')
will get a None
object if the corresponding field is submitted empty, thus len(None)
will raise TypeError: object of type 'NoneType' has no len()
最简单的解决方案可能是:提供一个支持内置 len()
方法
The simplest solution could be: providing a default value that support builtin len()
method
def signup(request):
if request.method == "POST":
# make empty string '' as default value instead of None
fname = request.POST.get('fname', '')
lname = request.POST.get('lname', '')
...
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