django从jsonfield的对象列表中获取价值总和

发布于 2025-02-04 18:11:22 字数 581 浏览 3 评论 0原文

我有一个具有以下实现的模型，

class MyModel(models.Model):
    data = models.JSONField(null=True, blank=True)

i具有这种格式的json：

{
  "name": "Name",
  "irrelevant_list": [],
  "items": [
    {
      "name": "Name 1",
      "quantity": 1,
      "other_list_of_objects": []
    },
    {
      "name": "Name 2",
      "quantity": 2,
      "other_list_of_objects": []
    }
  ]
}

我想用dentity的总和注释DB行（IE Quantity = 3对于此DB行），我尝试了多种方法，仍然没有正确的查询。

原文

I have a model with the following implementation

class MyModel(models.Model):
    data = models.JSONField(null=True, blank=True)

The I have json in this format:

{
  "name": "Name",
  "irrelevant_list": [],
  "items": [
    {
      "name": "Name 1",
      "quantity": 1,
      "other_list_of_objects": []
    },
    {
      "name": "Name 2",
      "quantity": 2,
      "other_list_of_objects": []
    }
  ]
}

I want to annotate db rows with the sum of quantity (i.e. quantity = 3 for this db row), I have tried multiple approaches, still not getting the right query.

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回眸一遍 2025-02-11 18:11:22

您可以添加一个名为数量 charfield的字段，然后覆盖clean（）方法
从实例中计算数量。如果您想在Django Admin以外保持一致性，请不要忘记覆盖save（）方法，以调用full_clean（）方法。
这样的东西

def clean(self):
    sum_of_quantities = 0
    for item in self.data['items']:
        sum_of_quantities += item['quantity']
    self.quantities = sum_of_quantities
    super(MyModel, self).clean()

def save(self, force_insert=False, force_update=False, *args, **kwargs):
    self.full_clean()
    instance = super(MyModel, self).save(force_insert, force_update, *args, **kwargs)
    return instance

You could add a field named quantities CharField, and override the clean() method
to calculate the quantities from the instance. Don't forget to override the save() method to call the full_clean() method if you wanna keep consistency outside of django admin.
Something like this

def clean(self):
    sum_of_quantities = 0
    for item in self.data['items']:
        sum_of_quantities += item['quantity']
    self.quantities = sum_of_quantities
    super(MyModel, self).clean()

def save(self, force_insert=False, force_update=False, *args, **kwargs):
    self.full_clean()
    instance = super(MyModel, self).save(force_insert, force_update, *args, **kwargs)
    return instance

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