python - django 表单 : erorr passing model foreign into a form choice field

Question

我正在处理一个包含来自其他模型的两个外键的表单和模型。这两个 fk 字段需要在模板中显示为选项。我能够做到这一点，表单呈现得很好，但是，在尝试保存它时出现错误。一些帖子提供了信息，但没有一个能解决我的问题。看来问题不在我搜索的地方，或者至少我无法找到并修复它。

这是我的 models.py

class Partners(models.Model):
    
    PartnerName = models.CharField(max_length=100, primary_key=True)
    PartnerCategory = models.CharField(max_length=100)
    PartnerPhoneNumber = models.CharField(max_length=100)
    PartnerEmail = models.CharField(max_length=100)
    PartnerCompany = models.CharField(max_length=100, default='non')
    PartnerAdressLine = models.CharField(max_length=100, default="NA")
    PartnerZipCode = models.CharField(max_length=100, default="NA")
    PartnerCity = models.CharField(max_length=100, default="NA")
    PartnerState = models.CharField(max_length=100, default="NA")

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


class Products(models.Model):
   
    ProductName = models.CharField(max_length=100, primary_key=True)
    ProductUnit = models.CharField(max_length=100, default="NA")
    ProductCategory = models.CharField(max_length=100)
    ProductTagNumber = models.IntegerField(max_length=100)
    StockOnHand = models.FloatField(max_length=100)
    
    def __str__(self):
               return str(self.ProductName)


class Sales(models.Model):
    SaleID = models.AutoField(max_length=100, primary_key=True)
    SaleProductName= models.ForeignKey(Products, on_delete=models.CASCADE)
    SalePartnersName = models.ForeignKey(Partners,on_delete=models.CASCADE)   
    SalePartnerBusinessName = models.CharField(max_length=100,default="NA")
    SaleQuantity = models.FloatField(max_length=100,default="NA")
    SaleUnit = models.CharField(max_length=100,default="NA")
    SaleNetAmount = models.FloatField(max_length=100)
    
    SalePartnerCommission = models.FloatField(max_length=100)
    SaleDate = models.DateField(default=datetime.date.today)
    SaleStatus = models.CharField(max_length=100,default="Ongoing")
    

这是我的views.py

def RecordNewDealView(request):
     
        if request.method == 'POST':
            form = RecordNewDealForm(request.POST)
            if form.is_valid():
                
                form.save()
            return redirect('my_deals.html') 
        else:
            form = RecordNewDealForm()
            context = {'form': form,}
            
            return render(request, 'record_new_deal.html', context)

最后是forms.py文件

brokers_df = pd.DataFrame(list(Partners.objects.all().values()))
brokers = brokers_df[brokers_df['PartnerCategory'] == 'Broker']

                       
items_list1 = brokers['PartnerName'].tolist()
items_list2 = brokers['PartnerName'].tolist()

CHOICES_OF_BROKERS = [list(x) for x in zip(items_list1, items_list2)]
CHOICES_OF_BROKERS.insert(0,('Not involved','Not involved'))


class RecordNewDealForm(forms.ModelForm):
       
                              
       SaleStatus = forms.CharField(widget=forms.Select(choices=SALE_STATUS_CHOICES))
       SalesBroker = forms.CharField(widget=forms.Select(choices=CHOICES_OF_BROKERS))
       SaleProductName = forms.ModelChoiceField(queryset=Products.objects.all().values_list('ProductName', flat=True))
       SalePartnerName = forms.ModelChoiceField(queryset=Partners.objects.all().values_list('PartnerName', flat=True))
       class Meta:
            model = Sales
            fields = ("SaleID",
                      "SaleProductName","SalePartnerName",
                      "SalePartnerBusinessName",
                      "SaleQuantity",
                      "SaleUnit","SaleNetAmount",
                      "SalePartnerCommission", "SaleDate"
                     
                     )

尝试将表单保存到数据库时，输出以下错误

Cannot assign "'Gummies'": "Sales.SaleProductName" must be a "Products" instance.

我对这个问题不熟悉，而且我找不到解决我问题的方法。现在已经过去几天了，我无法确定这段代码有什么问题，将不胜感激任何帮助!

更新:我看到这篇文章 Cannot assign must be a instance Django所以我尝试在模型中修改我的 fk:

SaleProductName= models.ForeignKey(Products, related_name='products_catalogue', on_delete=models.CASCADE,  blank=True, null=True)
    SalePartnersName = models.ForeignKey(Partners, related_name='partner_name', on_delete=models.CASCADE, blank=True, null=True) 

尝试保存表单时出现同样的错误

Answer 1

我不是 Django 的专家。但是，我认为问题出在 forms.py 中的以下代码块中。

   SaleProductName = forms.ModelChoiceField(queryset=Products.objects.all().values_list('ProductName', flat=True))
   SalePartnerName = forms.ModelChoiceField(queryset=Partners.objects.all().values_list('PartnerName', flat=True))

您正在尝试将字符串插入 ForeignKey 字段，这是不可能的。您要么必须按以下方式更改它。

   SaleProductName = forms.ModelChoiceField(queryset=Products.objects.all())
   SalePartnerName = forms.ModelChoiceField(queryset=Partners.objects.all())

您可以更改 Product 和 Partners 模型中的 __str__ 方法以分别显示“ProductName”和“PartnerName”。

    def __str__(self):
        return self.ProductName

否则，您可以保留 forms.py，因为它现在在 views.py 中处理此问题。但是，如果您还想使用此表单进行更新，则此方法会使问题复杂化。