Custom order field with Django Rest Framework-CodePudding

I have a model like

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']

I would like to order the quesryset by colorCode, but not as GREEN, RED, YELLOW items. I want to make the order like RED, YELLOW, GREEN items.

Is it possible? Is there something like Java Comparator? Thanks in advance.

CodePudding user response：

You could use the Python sorted function, but to take advantage of Django queries:

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')

Otherwise you could change your model:

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']