django-orm：如何更新一对一的关系字段值 [英] django-orm : How to update one-to-one relation field value

问题描述

models.py

  class Area（models.Model）：
 area_name = models.CharField（max_length = 255，null = False，blank = False）
描述= models.TextField（null = False，blank = False）
 
 class AreaPoint（models.Model）：
 x_axis = models.FloatField（default = 0.0）
 y_axis = models.FloatField（default = 0.0）
 area = models.OneToOneField（Area，primary_key = True，on_delete = models.CASCADE）
  

我尝试了两种方法，但是都失败了，请指导我。谢谢

 ＃第一种方法：
＃Area.objects.filter（id = 304）.update（area_name = 今天是1，description =今天是1，areapoint__x_axis = 111，areapoint__y_axis = 222）
＃错误：区域没有名为'areapoint__y_axis'的字段
 
＃第二种方法：
 obj = Area.objects.get（id = 304）
打印obj.areapoint.x_axis＃277 
打印obj.areapoint.y_axis＃65 
 obj.areapoint.x_axis = 100 
 obj.areapoint.y_axis = 200 
打印obj.areapoint.x_axis＃100 
打印obj.areapoint.y_axis＃200 
 obj.save（）
打印obj .areapoint.x_axis＃100 
打印obj.areapoint.y_axis＃200 
  

第二种方法

areapoint.x_axis 和 areapoint.y_axis 在更新后确实有所不同。
但是在我的数据库中。

解决方案

在两种方法中，您都尝试更新区域对象，而不是 AreaPoint 对象。

以下是两种方法的实现方法：

第一种方法：使用更新方法：

 ＃这是您的工作：
 Area.objects.filter（id = 304）.update（area_name = today is 1，
说明=今天是1，
 areapoint__x_axis = 111，
 areapoint__y_axis = 222）
  

以上将返回对象 Area ，并且由于没有字段 areapoint__x_axis 等，因此会引发错误。

您可以做的是在 AreaPoint 上进行过滤并更新：

  AreaPoint.objects.filter（area_id = 304）.update（x_axis = 111，y_axis = 222）
  

第二种方法：

  obj = Area.objects.get（id = 304）
 obj.areapoint.x_axis = 100 
 obj.areapoint.y_axis = 200 
 
＃保存obj.areapoint代替
 obj.areapoint.save（）
  

第三种方法：

  areapoint = AreaPoint.objects.get（area_id = 304）
 areapoint.x_axis = 100 
 areapoint.y_axis = 200 
 areapoint.save（）
  

models.py

class Area(models.Model):
    area_name = models.CharField(max_length=255, null=False, blank=False)
    description = models.TextField(null=False, blank=False)

class AreaPoint(models.Model):
    x_axis = models.FloatField(default=0.0)
    y_axis = models.FloatField(default=0.0)
    area = models.OneToOneField(Area,primary_key=True,on_delete=models.CASCADE)

I try two method , but both fail ,please guide me. thank you

# first method : 
# Area.objects.filter(id=304).update(area_name="today is 1", description="today is 1", areapoint__x_axis=111,areapoint__y_axis=222)
# error : Area has no field named 'areapoint__y_axis'

# second method : 
obj = Area.objects.get(id=304)
print obj.areapoint.x_axis # 277
print obj.areapoint.y_axis # 65
obj.areapoint.x_axis = 100
obj.areapoint.y_axis = 200
print obj.areapoint.x_axis # 100
print obj.areapoint.y_axis # 200
obj.save()
print obj.areapoint.x_axis # 100
print obj.areapoint.y_axis # 200

The second method is weird.
areapoint.x_axis and areapoint.y_axis are really different after update. But in my database.It still the same .

解决方案

In both the approach, you are trying to update the Area object and not the AreaPoint object.

Here is how you could do it using both approaches:

1st Approach: using update method:

# here is what you are doing:
Area.objects.filter(id=304).update(area_name="today is 1",
                                   description="today is 1",
                                   areapoint__x_axis=111,
                                   areapoint__y_axis=222)

Above will return an object of Area and since there are no fields areapoint__x_axis etc. it throws error.

What you could do is filter on AreaPoint instead and update it:

AreaPoint.objects.filter(area_id=304).update(x_axis=111, y_axis=222)

2nd Approach:

obj = Area.objects.get(id=304)
obj.areapoint.x_axis = 100
obj.areapoint.y_axis = 200 

# save obj.areapoint instead
obj.areapoint.save()

3rd Approach:

areapoint = AreaPoint.objects.get(area_id=304)
areapoint.x_axis = 100
areapoint.y_axis = 200
areapoint.save()

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