Django：检查数据库中是否已经存在更新的字段答案

【问题标题】：Django: Check if updated field is already present in databaseDjango：检查数据库中是否已经存在更新的字段
【发布时间】：2019-11-11 07:42:53
【问题描述】：

我正在尝试使用电子邮件作为字段来更新 django ModelForm。在创建表单中，我正在检查该字段是否已存在于数据库中，如果存在则引发验证错误。该部分按预期工作。

但是，如果我在更新表单中使用相同的检查，则会引发验证错误，因为现有记录具有给定的电子邮件。是否有直接的方法来确保此验证？

forms.py

class MyObjCreateForm(forms.ModelForm):
    first_name = forms.CharField(max_length=50, label='First name')
    last_name = forms.CharField(max_length=50, label='Last name')
    email = forms.EmailField(label='Email')
    location = forms.ChoiceField(choices=TP_TM_Location, label='Location')
    designation = forms.ChoiceField(choices=TP_TM_Designation, label='Designation')
    date_of_joining = forms.DateField(label='Date of joining',
                                    widget=forms.TextInput(attrs={'type': 'date'}),
                                    initial=date.today())
    username = forms.CharField(label='Login username')
    password = forms.CharField(widget=forms.PasswordInput(), label='Login password')
    current_status = forms.ChoiceField(choices=TP_Status, label='Current status')

    def clean_email(self):
        email = self.cleaned_data.get('email')
        try:
            match = MyObj.objects.get(email=email)
            raise forms.ValidationError("email already exists in system. Please check the existing list.")
        except MyObj.DoesNotExist:
            return email

class MyObjUpdateForm(forms.ModelForm):
    first_name = forms.CharField(max_length=50, label='First name')
    last_name = forms.CharField(max_length=50, label='Last name')
    email = forms.EmailField(label='Email')
    location = forms.ChoiceField(choices=TP_TM_Location, label='Location')
    designation = forms.ChoiceField(choices=TP_TM_Designation, label='Designation')
    date_of_joining = forms.DateField(label='Date of joining',
                                    widget=forms.TextInput(attrs={'type': 'date'}),
                                    initial=date.today())
    current_status = forms.ChoiceField(choices=TP_Status, label='Current status')
    username = forms.CharField(label='Login username')

    def clean_email(self):
        email = self.cleaned_data.get('email')
        try:
            match = MyObj.objects.get(email=email)
            raise forms.ValidationError("email already exists in system. Please check the existing list.")
        except MyObj.DoesNotExist:
            return email

谢谢，

【问题讨论】：

标签： django validation django-forms

【解决方案1】：

为此，您需要像这样从查询集中排除当前用户。

    def clean_email(self):
        email = self.cleaned_data.get('email')
        email_match = MyObj.objects.filter(email=email).exclude(pk=self.instance.pk)  
        if self.instance and self.instance.pk and not email_match:
            return email
        else:
            raise forms.ValidationError("email already exists in system. Please check the existing list.")

【讨论】：

【解决方案2】：

您需要删除更新类中的验证。您可以直接退回电子邮件而无需验证。

def clean_email(self):
    return self.cleaned_data.get('email')

但是，如果您想检查用户是否已经拥有新的电子邮件，那么您可以使用以下验证方法：

def clean_email(self):
    email = self.cleaned_data.get('email')
    if self.instance.email == email:
        raise forms.ValidationError("Email already present.")
    return email

【讨论】：