Python Django：访问给定字段的选择元组
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Django: Access given field's choices tuple
提问by Furbeenator
I would like to get the named values of a choices field for a choice that is not currently selected. Is this possible?
我想获取当前未选择的选项的选项字段的命名值。这可能吗？
For instance: models.py
例如：models.py
FILE_STATUS_CHOICES = (
('P', 'Pending'),
('A', 'Approved'),
('R', 'Rejected'),
)
class File(models.Model):
status = models.CharField(max_length=1, default='P', choices=FILE_STATUS_CHOICES)
views.py
视图.py
f = File()
f.status = 'P'
f.save()
old_value = f.status
print f.get_status_display()
> Pending
f.status = 'A'
f.save()
new_value = f.status
print f.get_status_display()
> Approved
How can I get the old display value from the 'P' to 'Pending?' I may be able to do so by creating a form in the view and accessing its dictionary of values/labels. Is this the best/only approach?
如何从“P”到“Pending”获取旧的显示值？我可以通过在视图中创建一个表单并访问它的值/标签字典来做到这一点。这是最好/唯一的方法吗？
采纳答案by alecxe
This is pretty much ok to import your choice mapping FILE_STATUS_CHOICESfrom models and use it to get Pendingby P:
这是非常确定导入你的选择映射FILE_STATUS_CHOICES从模型，并用它来获得Pending的P：
from my_app.models import FILE_STATUS_CHOICES
print dict(FILE_STATUS_CHOICES).get('P')
get_FIELD_display()method on your model is doing essentially the same thing:
get_FIELD_display()模型上的方法基本上做同样的事情：
def _get_FIELD_display(self, field):
value = getattr(self, field.attname)
return force_text(dict(field.flatchoices).get(value, value), strings_only=True)
And, since there is a flatchoicesfield on the model field, you can use it with the help of _metaand get_field_by_name()method:
并且，由于flatchoices模型字段上有一个字段，您可以在_meta和get_field_by_name()方法的帮助下使用它：
choices = f._meta.get_field_by_name('name')[0].flatchoices
print dict(choices).get('P')
where fis your model instance.
f你的模型实例在哪里。
Also see:
另见：
回答by Ibrohim Ermatov
I recommend using Choicefrom django-model-utils: https://django-model-utils.readthedocs.io/en/latest/utilities.html#choices.
我建议使用Choice来自django-model-utils：https://django-model-utils.readthedocs.io/en/latest/utilities.html#choices。
I use it in every my models if I need choice field. See examples, it has excellent options.
如果我需要选择字段，我会在我的每个模型中使用它。查看示例，它有很好的选择。
