Django 检索组 ChoiceField 的键

Question

检索组 ChoiceField 的键

MEDIA_CHOICES = (
('Audio', (
        ('vinyl', 'Vinyl'),
        ('cd', 'CD'),
    )
),
('Video', (
        ('vhs', 'VHS Tape'),
        ('dvd', 'DVD'),
    )
),
('unknown', 'Unknown'),

)

class ressource(models.Model):
....

media = models.CharField(max_length=50, choices=MEDIA_CHOICES)

在现场媒体中，我有黑胶唱片或 cd 或 vhs 或 dvd...但是如何检索音频、视频、未知？

Answer 1

你应该向我们证明更多细节。首先选择应该是iterable 对象（例如tuple，在你的情况下），但你的tuple 在你的情况下非常复杂（Django 无法处理这个）。你应该传递这样的东西作为选择。

选择示例（这是很好的元组代码）

CHOICES = (
    ('key', 'value') # key will be inserted in database (and validation purposes), and  value is just for representation purposes.
)
LANGUAGES = (
    ('python', 'Python'),
    ('js', 'JS'),
    ('ruby', 'Ruby'),
)

想象一下，您正试图从数据库中检索对象。

class ressource(models.Model):
    ''' This is your model '''
    media = models.CharField(max_length=50, choices=MEDIA_CHOICES)

res = ressource.objects.get(pk=1) # retrieve data from database.
print(res.media) # returns string object. you will read actual value of media field
''' But if you want to read all available choices on this field, Django provide as _meta api. You can use it very nice way '''
res = ressource.objects.get(pk=1)
fields = res._meta.fields # This will return tuple-like object.
for field in fields:
    if field.name == 'media':
        # you want to find "media" field
        print(field.choices) # This will return all available choices on your media field

希望对您有所帮助。祝你好运。