IntegrityError in django duplicated key

Question

Hello I have a form on django that im trying to validate so it does not allow duplicated values, as of right now when you enter a duplicated value it raises this error on the app:

Exception Type: IntegrityError
Exception Value:    
duplicate key violates uniqueness restriction «utiles_employee_user_id_key»
DETAIL:  The key already exists (user_id)=(3).

Here's my form:

class EmployeeForm(Form):
    first_name = CharField(max_length=40, label=_('Nombre'))
    last_name = CharField(max_length=40, label=_('Apellido'))
    children = IntegerField(label=_('Cantidad de Hijos'), required=False)
    email2 = EmailField(label=_('Correo electrónico personal'), required=False)
    email = EmailField(label=_('Correo electrónico Corporativo'))
    company = ModelChoiceField(queryset=Company.objects.all(), required=False, label=_('Empleado de'))

    def __init__(self, data=None, files=None, auto_id='id_%s', prefix=None, initial=None, error_class=ErrorList,
                 label_suffix=None, empty_permitted=False, user=None):
        super().__init__(data, files, auto_id, prefix, initial, error_class, label_suffix, empty_permitted)
        if not user.is_staff:
            self.fields['company'].queryset = Company.objects.filter(id=user.employee.company.id)

how can I raise an error message saying to the user that it entered a duplicated object, as of right now the app crashes when I do.

EDIT: I added this method to the form but the problem persist.

    def clean(self):
        cd = self.cleaned_data['email']
        user = Employee.objects.get(email2=cd)
        if self.instance and not user == self.instance:
            raise ValidationError('trial msg')
        return cd
            

but now i get this error:

Exception Type: AttributeError
Exception Value:    
'EmployeeForm' object has no attribute 'instance'

Answer 1

You can achieve the desired behavior using the clean method. This method is present either on the Field definition itself and also on the Form .

You can find more detailed information on Django's documentation:

• Cleaning using the FormField itself
• Cleaning a specific form attribute
• More general form cleaning

By raising a ValidationError when the duplicate data is present, it will allow you to detect the issue in the view and then display/render the desired error message.