Question

我有一个名为billing的应用。以下是我的应用中的模型。

class ProductType(models.Model):
    name = models.CharField(max_length=128)
    unique_id = models.CharField(max_length=128)
    price = models.DecimalField(max_digits=50,decimal_places=4)

class Product(models.Model):
    type = models.ForeignKey(ProductType,related_name="products")
    mac_id = models.CharField(max_length=128)
    product_unique_id = models.CharField(max_length=128)
    assigned = models.BooleanField(default=False)

class BillRecord(models.Model):
    products = models.ManyToManyField(Product, related_name="billrecords",blank=True)
    send_sms = models.BooleanField(default=True)
    send_email = models.BooleanField(default=True)
    invoice = models.FileField(null=True,blank=True,upload_to='invoices/')

    def save(self, *args, **kwargs):
        super(BillRecord, self).save(*args, **kwargs)
        total_products = Product.objects.filter(assigned=False)
        self.products.add(*total_products)

保存BillRecord对象并查询对象products后返回billing.Product.None

如何在products模型的保存方法中添加BillRecord。

Answer 1

您需要更改保存方法

def save(self, *args, **kwargs):
    item = super(BillRecord, self).save(*args, **kwargs)
    total_products = Products.objects.filter(assigned=False)
    item.products.add(*total_products)
    item.save()

首先，调用super（）。save方法，然后添加要与自身对象关联的对象。

Answer 2

管理员中的多对多保存将无法正常工作。您需要像这样覆盖Admin类....

class BillRecordAdmin(admin.ModelAdmin):

    def save_model(self, request, obj, form, change):
        super(ArticleAdmin, self).save_model(request, obj, form, change)
        total_products = Product.objects.filter(assigned=False)
        form.instance.products.add(*total_products)


admin.site.register(BillRecord, BillRecordAdmin)

Answer 3

您正在尝试向billrecord对象添加多对多字段对象，这就是您收到错误的原因，“

"<BillRecord: test>" needs to have a value for field "billrecord" before this many-to-many relationship can be used"

首先，您需要保存BillRecord模型的对象，然后将该对象的查询集添加到多对多关系中。

ManyToMany字段没有保存Django

3 个答案: