django.db.utils.IntegrityError：唯一约束失败：new__bank_profile.fname_id

Question

i was trying to migrate and this error occurred.

django.db.utils.IntegrityError: UNIQUE constraint failed: new__bank_profile.fname_id

i was trying to extend User model and that happened.following are my views and models.

my views:

def dashboard(request):
    if request.method=="POST":
        fname = request.POST.get('fname')
        age = request.POST.get('age')
        gender = request.POST.get('gender')
        address = request.POST.get('address')
        occupation = request.POST.get('occupation')
        bio = request.POST.get('bio')
        img = request.POST.get('img')
        filename = request.POST.get('filename')
        user=profile(fname=fname,age=age,gender=gender,address=address,occupation=occupation,bio=bio,img=img,filename=filename)
        user.save()    
        return render(request, 'bank/index2.html')            
    else:
        return render(request, 'bank/signin.html')

my models:

from django.db import models
from django.contrib.auth.models import User
from django.db.models.signals import post_save
from django.dispatch import receiver

class profile(models.Model):
    fname = models.OneToOneField(User,max_length=50,default="",blank=True,null=True,on_delete=models.CASCADE,related_name='fname',unique=True)
    #fname = models.CharField(max_length=500,default="",blank=True,null=True)
    age = models.CharField(max_length=3,default="",blank=True,null=True)
    address = models.CharField(max_length=500,default="",blank=True,null=True)
    occupation = models.CharField(max_length=150, default="",blank=True,null=True)
    bio = models.TextField(max_length=500, blank=True,null=True,default="")
    img = models.ImageField(upload_to='bank/images', default="",blank=True,null=True)
    filename = models.ImageField(upload_to='bank/images', default="",blank=True,null=True)
    GENDER_CHOICES = (
        ('M', 'Male'),
        ('F', 'Female'),
    )
    gender = models.CharField(max_length=1, choices=GENDER_CHOICES, default="",blank=True,null=True)

    def __str__(self):
        return str(self.fname)

Answer 1

You defined your variables inside the "if statement". Try to change that. Try putting the "if statement" above the "user.save()".

Answer 2

The fname field in the profile shouldn't allow blank values because you are extending a user model and fname field is like the primary key of the profile model, primary keys shouldn't be blank . So remove blank true and null true on the fname field.

Another problem on your view , the user shouldn't provide a primary key on the form while creating a profile. The user should come automatically from the request object. Like request.user.id . This is the best practice I guess and not:-

This is bad

fname = request. Form.get('fname')

Remove this and provide the authenticated request.user directly to the profile model when the user is creating the profile

Answer 3

"If you have not started with a custom user model from the very first migrate command you run, then you're in for a world of hurt because User is tightly interwoven with the rest of Django internally. It is challenging to switch over to a custom user model mid- project. A point of confusion for many people is that custom user models were only added in Django 1.5. Up until that point the recommended approach was to add a One- ToOneField53, often called a Profile model, to User. You'll often see this set up in older projects. But these days using a custom user model is the more common approach. However as with many things Django-related, there are implementation choices: either extend AbstractUser54 which keeps the default User fields and permissions or extend Ab- stractBaseUser55 which is even more granular, and flexible..." Extract from Django for professionals by William s. Vincent