使用 Django Rest 框架的自定义订单字段

Question

我有个模特就像

class MyModel(models.Model):
    COLOR_CODES = ['RED', 'YELLOW', 'GREEN']
    name = models.CharField(db_column='name', max_length=200, blank=False, null=False, unique=True)
    colorCode = EnumField(db_column='color_code', choices=COLOR_CODES, null=False, default='GREEN')
    

    class Meta:
        managed = True
        db_table = 'MyModel'
        ordering = ['colorCode']

我想按色标订购quesryset，但不是绿色、红色、黄色产品。我想订购红色、黄色、绿色的产品。

可能吗？有没有像Java Comparator这样的东西？提前谢谢。

Answer 1

您可以使用Python排序函数，但要利用Django查询：

from django.db.models import Value, IntegerField, When, Case
# Don' t set the default order in the model (this also improves performance), simply write this query when you need this particular order
MyModel.objects.annotate(order=Case(When(colorCode='RED', then=0), When(colorCode='YELLOW', then=1), default=Value(2), output_field=IntegerField())).order_by('order')

否则，您可以更改模型：

from enum import Enum

class MyModel(models.Model):
   class ColorCodes(Enum):
      # In the admin interface you will see 'red' and not '0r' (so don't worry about ugly names), the second value is stored in the database and is used for order the queryset
      red = ('red', '0r')
      yellow = ('yellow', '1y')
      green  = ('green', '2g')
      
      @classmethod
      def get_value(cls, member):
         return cls[member].value[0]
  

   colorCode = CharField(db_column='color_code', null=False, default=ColorCodes.get_value('green'), max_length=2, choices=[x.value for x in ColorCodes])
    
   class Meta:
      managed = True
      db_table = 'MyModel'
      ordering = ['colorCode']