Python 自动为Django模型中的每个选项添加常量
在Django中,我经常使用以下模式:Python 自动为Django模型中的每个选项添加常量,python,django,django-models,Python,Django,Django Models,在Django中,我经常使用以下模式: class MyModel(models.Model): FOO = 1 BAR = 2 GOO = 3 BLAH_TYPES = ( (FOO, 'Foodally boogaly'), (BAR, 'Bar bar bar bar'), (GOO, 'Goo goo gaa gaa'), ) TYPE_FOR_ID = dict(BLAH_TYPES)
class MyModel(models.Model):
FOO = 1
BAR = 2
GOO = 3
BLAH_TYPES = (
(FOO, 'Foodally boogaly'),
(BAR, 'Bar bar bar bar'),
(GOO, 'Goo goo gaa gaa'),
)
TYPE_FOR_ID = dict(BLAH_TYPES)
ID_FOR_TYPE = dict(zip(TYPE_FOR_ID.values(), TYPE_FOR_ID.keys()))
blah = models.IntegerField(choices=BLAH_TYPES)
是否有一种其他人遵循的好模式可以实现相同的效果(即,我可以访问具有名称的常量和双向的字典)?这是初始化常量的最简洁的方法:
# foobar choices constants
FOO, BAR, BAZ = range(3)
# bebop choices constants (if you prefer this to readability)
(BUU,
BAA,
DII,
DUU) = range(4)
# then, in a galaxy far away, much to your expectations:
>> FOO
0
>> DII
2
在任何情况下,我通常会创建一个const.py
,并将所有的疯狂都保留在那里(只看一个98行长的),但一定要将它们移出模型类,并将它们作为模块数据的一部分,以节省时间和内存,除非您做一些动态的事情
否则,你就要尽可能地做好这件事。我还做了一个
BLAH_TYPES
,以符合每个开发人员都习惯于阅读的Django choices结构。这是你无法避免的,也无法走捷径的一部分。如果我需要这些转换,比如ID\u FOR_TYPE
,我只需在选项下面定义它们。可读、干净、紧凑。卡尔·迈耶的图书馆有一个很好的解决方案——选择类,它允许您声明一个通过人类可读属性访问的选择列表。我也有同样的渴望,这就是我写的:
from django.db import models
from django.db.models.base import ModelBase
import re
class ModelBaseWithChoices(ModelBase):
def __new__(cls, name, bases, attrs):
def format_label(label):
return re.sub('[^A-Z]+', '_', label.upper()).strip('_')
def get_choices(attrs):
for attr, value in attrs.items():
if attr.endswith('_CHOICES') and isinstance(value, tuple):
base = '_'.join(attr.split('_')[:-1])
for val, label in value:
yield '_'.join((base, format_label(label))), val
attrs.update(list(get_choices(attrs)))
return super(ModelBaseWithChoices, cls).__new__(cls, name, bases, attrs)
class ModelWithChoices(models.Model):
__metaclass__ = ModelBaseWithChoices
class Meta:
abstract = True
从那里,您可以将MyModel
改写为:
class MyModel(ModelWithChoices):
BLAH_CHOICES = ((1, 'Foodally boogaly'),
(2, 'Bar bar bar bar'),
(3, 'Goo goo gaa gaa'))
blah = models.IntegerField(choices = BLAH_CHOICES)
并在模型中自动为您创建所有常量。从Django shell:
>>> MyModel.BLAH_FOODALLY_BOOGALY
1
>>> MyModel.BLAH_GOO_GOO_GAA_GAA
3