使用 unique_together 并保存经过身份验证的用户时出现问题

Question

我的代码中存在两个字段条目唯一性检查的问题。

我用unique_together 定义了一个模型来检查每个用户的字段记录的唯一性，但它接受该用户添加的重复条目。

model.py

from django.db import models
from django.contrib.auth.models import User

class UserItem(models.Model):
    definer = models.ForeignKey(User, on_delete=models.CASCADE)
    item_name = models.CharField(max_length=50)
    .
    .
    class Meta:
        unique_together = ("definer", "item_name")

views.py

from django.contrib.auth.mixins import LoginRequiredMixin, UserPassesTestMixin
from django.views.generic.edit import CreateView, UpdateView, DeleteView

class RecordCreateView(LoginRequiredMixin, CreateView):
    model = UserItem
    template_name = 'item_new.html'
    #excluding "definer" field and inserting its value by form_valid
    fields = ['item_name', . . .]   

    def form_valid(self, form):
        form.instance.definer = self.request.user
        return super().form_valid(form)

我希望警告并阻止用户使用之前添加的相同“item_name”添加新记录，但它接受它们（没有警告）。

当我用其他字段替换“定义器”时，它可以正常工作并警告重复记录。此外，当管理员添加记录时，它会起作用并且会出现预期的警告。

我想，这个问题是因为在“unique_together = ("definer", "item_name")" 完成其角色之后，经过身份验证的用户被 "def form_valid" 插入为 "definer"。另一方面，当“定义器”为空时进行唯一性检查。

我应该怎么做才能解决这个问题？

编辑：添加完整模型

```` Full Model in model.py
class UserItem(models.Model):
    item_type = models.CharField(max_length=12, verbose_name='Item type')
    item_name = models.CharField(max_length=50)
    bound = models.CharField(null=True, blank=True, default=None, max_length=4, verbose_name='Bound')
    price = models.FloatField(default=0)
    maximum_use = models.FloatField(default=0, verbose_name='Maximum use (%)’)
    matterial = models.FloatField(null=True, blank=True, default=None, verbose_name='matterial (%)')
    energy = models.FloatField(null=True, blank=True, default=None, verbose_name='energy (kcal/k)')

    definer = models.ForeignKey(User, on_delete=models.CASCADE)

    def __str__(self):
        return "{}, name: {}, definer: {}".format(self.item_type, self.item_name, self.definer,)

    def get_absolute_url(self):
        return reverse('profile')

    class Meta:
        unique_together = ("definer", "item_name")
````


```` views.py after @Pedro suggestion to edit
from django.db import IntegrityError
from django.http import HttpResponse, HttpResponseRedirect
from django.urls import reverse
from django.views.generic.edit import CreateView, UpdateView, DeleteView
from django.contrib.auth.models import User
from django.contrib.auth.mixins import LoginRequiredMixin

class RecordCreateView(LoginRequiredMixin, CreateView):
    model = UserItem
    template_name = 'item_new.html'
    fields = ['item_name', 'matterial', 'energy',]

    def get_success_url(self):
        return reverse('profile')

    def form_valid(self, form):
        user_item = form.save(commit=False)
        user_item.definer = self.request.user
        user_item.item_type = 'required'
        user_item.bound = 'min'
        try:
            user_item.save()
        except IntegrityError:
            form.add_error('item_name', 'Item name is repeated')
            return self.form_invalid(form)
        return HttpResponseRedirect(self.get_success_url())
````

Answer 1

感谢@Pedro 非常有用的提示；最后，我可以通过对他的代码进行一些更改来解决我的问题。

我还删除了 model.py 中的这一部分： “类元： unique_together = ("定义器", "item_name")"

````views.py
class RecordCreateView(LoginRequiredMixin, CreateView):
    model = UserItem
    template_name = 'item_new.html'
    fields = ['item_name', 'matterial', 'energy',]

    def form_valid(self, form):
        user_items = form.save(commit=False)
        item_name = user_items.item_name
        qs = UserItemComposition.objects.filter(definer=self.request.user, item_name=item_name)
        if qs.exists():
            form.add_error('item_name', 'Item name is repeated')
            return self.form_invalid(form)
        form.instance.definer = self.request.user
        return super().form_valid(form)
````

Answer 2

问题是您在验证表单后添加definer。您可以将request.user 作为初始数据传递，如下所示：

class RecordCreateView(LoginRequiredMixin, CreateView):
    model = UserItem
    template_name = 'item_new.html'
    #excluding "definer" field and inserting its value by form_valid
    fields = ['item_name', 'definer', ...]

    def get_initial(self):
        initial = super().get_initial()
        initial['definer'] = self.request.user
        return initial

现在您不需要覆盖form_valid。

编辑：如果您不想在表单字段中出现definer，您可以这样做：

class RecordCreateView(LoginRequiredMixin, CreateView):
    model = UserItem
    template_name = 'item_new.html'
    fields = ['item_name', ...]

    def form_valid(self, form):
        user_item = form.save(commit=False)
        user_item.definer = self.request.user
        try:
            user_item.save()  # should raise an exception if unique_together constrain fails
        except ValidationError:
            form.add_error('item_name', 'Item name is repeated')  # add custom error to form
            return self.form_invalid(form)  # return the invalid form
        return HttpResponseRedirect(self.get_success_url())