django - UNIQUE 约束失败：Django 中的 Users.username 错误

Question

由于一些未知的原因，我面临着这个错误

我已经搜索了一些可能的错误，但我尝试过的那些都不起作用

我试过 user = form.save(commit=False)也许它会起作用，但没有积极的结果

错误日志：

Environment:


Request Method: POST
Request URL: http://localhost:8000/accounts/register-result

Django Version: 3.1.2
Python Version: 3.7.3
Installed Applications:
['django.contrib.admin',
 'django.contrib.auth',
 'django.contrib.contenttypes',
 'django.contrib.sessions',
 'django.contrib.messages',
 'django.contrib.staticfiles',
 'apps.accounts',
 'apps.result']
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',
 'apps.result.middleware.LoginRequiredMiddleware']



Traceback (most recent call last):
  File "C:\Users\Habib\Documents\django\django-new\resultLab\venv\lib\site-packages\django\db\backends\utils.py", line 84, in _execute
    return self.cursor.execute(sql, params)
  File "C:\Users\Habib\Documents\django\django-new\resultLab\venv\lib\site-packages\django\db\backends\sqlite3\base.py", line 413, in execute
    return Database.Cursor.execute(self, query, params)

The above exception (UNIQUE constraint failed: Users.username) was the direct cause of the following exception:
  File "C:\Users\Habib\Documents\django\django-new\resultLab\venv\lib\site-packages\django\core\handlers\exception.py", line 47, in inner
    response = get_response(request)
  File "C:\Users\Habib\Documents\django\django-new\resultLab\venv\lib\site-packages\django\core\handlers\base.py", line 179, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "C:\Users\Habib\Documents\django\django-new\resultLab\apps\accounts\views.py", line 32, in register_school
    user = User.objects.create_user(username=username,email=email,password=password)
  File "C:\Users\Habib\Documents\django\django-new\resultLab\venv\lib\site-packages\django\contrib\auth\models.py", line 146, in create_user
    return self._create_user(username, email, password, **extra_fields)
  File "C:\Users\Habib\Documents\django\django-new\resultLab\venv\lib\site-packages\django\contrib\auth\models.py", line 140, in _create_user
    user.save(using=self._db)
  File "C:\Users\Habib\Documents\django\django-new\resultLab\venv\lib\site-packages\django\contrib\auth\base_user.py", line 67, in save
    super().save(*args, **kwargs)
  File "C:\Users\Habib\Documents\django\django-new\resultLab\venv\lib\site-packages\django\db\models\base.py", line 754, in save
    force_update=force_update, update_fields=update_fields)
  File "C:\Users\Habib\Documents\django\django-new\resultLab\venv\lib\site-packages\django\db\models\base.py", line 792, in save_base
    force_update, using, update_fields,
  File "C:\Users\Habib\Documents\django\django-new\resultLab\venv\lib\site-packages\django\db\models\base.py", line 895, in _save_table
    results = self._do_insert(cls._base_manager, using, fields, returning_fields, raw)
  File "C:\Users\Habib\Documents\django\django-new\resultLab\venv\lib\site-packages\django\db\models\base.py", line 935, in _do_insert
    using=using, raw=raw,
  File "C:\Users\Habib\Documents\django\django-new\resultLab\venv\lib\site-packages\django\db\models\manager.py", line 85, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "C:\Users\Habib\Documents\django\django-new\resultLab\venv\lib\site-packages\django\db\models\query.py", line 1254, in _insert
    return query.get_compiler(using=using).execute_sql(returning_fields)
  File "C:\Users\Habib\Documents\django\django-new\resultLab\venv\lib\site-packages\django\db\models\sql\compiler.py", line 1397, in execute_sql
    cursor.execute(sql, params)
  File "C:\Users\Habib\Documents\django\django-new\resultLab\venv\lib\site-packages\django\db\backends\utils.py", line 98, in execute
    return super().execute(sql, params)
  File "C:\Users\Habib\Documents\django\django-new\resultLab\venv\lib\site-packages\django\db\backends\utils.py", line 66, in execute
    return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
  File "C:\Users\Habib\Documents\django\django-new\resultLab\venv\lib\site-packages\django\db\backends\utils.py", line 75, in _execute_with_wrappers
    return executor(sql, params, many, context)
  File "C:\Users\Habib\Documents\django\django-new\resultLab\venv\lib\site-packages\django\db\backends\utils.py", line 84, in _execute
    return self.cursor.execute(sql, params)
  File "C:\Users\Habib\Documents\django\django-new\resultLab\venv\lib\site-packages\django\db\utils.py", line 90, in __exit__
    raise dj_exc_value.with_traceback(traceback) from exc_value
  File "C:\Users\Habib\Documents\django\django-new\resultLab\venv\lib\site-packages\django\db\backends\utils.py", line 84, in _execute
    return self.cursor.execute(sql, params)
  File "C:\Users\Habib\Documents\django\django-new\resultLab\venv\lib\site-packages\django\db\backends\sqlite3\base.py", line 413, in execute
    return Database.Cursor.execute(self, query, params)

Exception Type: IntegrityError at /accounts/register-result
Exception Value: UNIQUE constraint failed: Users.username

意见：

def register_school(request):
if request.method == 'POST':
    form = SchoolRegistrationForm(request.POST)
    if form.is_valid():
        cleaned = form.cleaned_data
        username = cleaned['username']
        password = cleaned['password']
        email = cleaned['email']
        school_name = cleaned['school_name']
        address = cleaned['address']
        user = User.objects.create_user(username=username,email=email,password=password)
        user.usertype = 'result'
        user = form.save(commit=False)
        user.save()
        school = School(user=user,
                        name=school_name,
                        address=address,
                        )
        school.save()
        return redirect(reverse('registration-complete', kwargs={'username': username}))
else:
    form = SchoolRegistrationForm
    return render(request, 'registration.html', {'form': form})

形式：

class SchoolRegistrationForm(forms.Form):
    username = forms.CharField(label='Username')
    password = forms.CharField(label='Password', widget=forms.PasswordInput)
    password_second = forms.CharField(label='Password', widget=forms.PasswordInput)
    email = forms.EmailField(label='Email Address')
    school_name = forms.CharField(label='School Name')
    address = forms.CharField(label='Office Address')

标签： djangodjango-modelsdjango-formsdjango-views

Answer 1

该错误只是表示username您输入的内容已存在于数据库中。要解决此问题，请username为SchoolRegistrationForm. 此外，form.save(commit=False)由于表单不是ModelForm.

只有基于模型的表单ModelForm具有内置的保存方法。对于基于 的表单Form，您必须创建一个模态对象并保存该实例。

def register_school(request):
    if request.method == 'POST':
        form = SchoolRegistrationForm(request.POST)
        if form.is_valid():
            cleaned = form.cleaned_data

            # https://docs.djangoproject.com/en/3.1/topics/auth/default/#creating-users
            username = cleaned['username']
            password = cleaned['password']
            email = cleaned['email']
            user = User.objects.create_user(
                username=username,
                email=email,
                password=password
                )
            user.usertype = 'result'
            user.save()

            # create model instance and save()
            school_name = cleaned['school_name']
            address = cleaned['address']
            school = School(
                user=user,
                name=school_name,
                address=address,
                )
            school.save()
            return redirect(reverse('registration-complete', kwargs={'username': username}))     
    else:
        form = SchoolRegistrationForm()
        return render(request, 'registration.html', {'form': form})

向表单中的username字段添加验证。这将检查用户名是否已经存在，并在创建视图SchoolRegistrationForm时在表单中引发验证错误，而不是模式错误。User

# forms.py
# imports
from django.core.exceptions import ValidationError
from django.contrib.auth import get_user_model

class SchoolRegistrationForm(forms.Form):
    username = forms.CharField(label='Username')
    # other fields

    # https://docs.djangoproject.com/en/3.1/ref/forms/validation/#cleaning-a-specific-field-attribute
    def clean_username(self):
        data = self.cleaned_data['username']
        user_model = get_user_model()
        if user_model.objects.filter(username=data).exists():
            raise ValidationError("Username already exists")

        # Always return a value to use as the new cleaned data, even if
        # this method didn't change it.
        return data