Django Web应用注册时重复创建两个Profile问题求助

问题核心原因 #

你遇到的重复创建Profile的问题，大概率是两种创建逻辑重复触发：

• 视图代码里手动调用了Profile.objects.create创建实例
• 你的Profile模型可能配置了post_save信号，在User对象创建时自动生成Profile

两种逻辑叠加，就会导致每次注册生成两个Profile实例。另外，视图里通过create_user已经得到了user对象，没必要再用User.objects.get(username=username)重复查询，这属于冗余代码，但不会直接导致重复创建。

解决方案 #

方案1：移除视图手动创建逻辑（推荐） #

如果你的models.py中存在如下自动创建Profile的信号配置：

# models.py中的信号代码示例
from django.db.models.signals import post_save
from django.contrib.auth.models import User
from django.dispatch import receiver
from .models import Profile

@receiver(post_save, sender=User)
def create_profile(sender, instance, created, **kwargs):
    if created:
        Profile.objects.create(user=instance)

则需要删除视图里手动创建Profile的代码，优化后的视图代码如下：

def signup(request):
    
    if request.method == "POST":
        print("Signup view called")
        
        username = request.POST["username"]
        email = request.POST["email"]
        password = request.POST["password"]
        password2 = request.POST["password2"]
        
        if password == password2:
            if User.objects.filter(email=email).exists():
                messages.info(request, "Email Taken")
                return redirect("signup")
            elif User.objects.filter(username=username).exists():
                messages.info(request, "Username Taken")
                return redirect("signup")
            else:
                # create_user方法会自动保存用户，无需额外调用user.save()
                User.objects.create_user(username=username, email=email, password=password)
                return redirect("signup")
        else:
            messages.info(request, "Password Not Matching")
            return redirect("signup")
    else:
        return render(request, "signup.html")

方案2：移除信号逻辑，保留视图手动创建 #

如果不需要信号自动生成Profile，先删除models.py中的post_save信号代码，再优化视图里的冗余查询：

def signup(request):
    
    if request.method == "POST":
        print("Signup view called")
        
        username = request.POST["username"]
        email = request.POST["email"]
        password = request.POST["password"]
        password2 = request.POST["password2"]
        
        if password == password2:
            if User.objects.filter(email=email).exists():
                messages.info(request, "Email Taken")
                return redirect("signup")
            elif User.objects.filter(username=username).exists():
                messages.info(request, "Username Taken")
                return redirect("signup")
            else:
                user = User.objects.create_user(username=username, email=email, password=password)
                # 直接使用已创建的user对象，无需重复查询
                Profile.objects.create(user=user)
                # create方法自动保存实例，无需调用new_profile.save()
                return redirect("signup")
        else:
            messages.info(request, "Password Not Matching")
            return redirect("signup")
    else:
        return render(request, "signup.html")

内容的提问来源于stack exchange，提问作者Usman Ndako