/Python/Unique mark boolean django model field

Unique mark boolean django model field

#FIELDS.py

from django.db.models import BooleanField


class UniqueBooleanField(BooleanField):
    def pre_save(self, model_instance, add):
        objects = model_instance.__class__.objects
        # If True then set all others as False
        if getattr(model_instance, self.attname):
            objects.update(**{self.attname: False})
        # If no true object exists that isnt saved model, save as True
        elif not objects.exclude(id=model_instance.id)\
                        .filter(**{self.attname: True}):
            return True
        return getattr(model_instance, self.attname)

# To use with South
from south.modelsinspector import add_introspection_rules
add_introspection_rules([], ["^project\.apps\.fields\.UniqueBooleanField"])


#Models.py
from django.db import models

from project.apps.fields import UniqueBooleanField


class UniqueBooleanModel(models.Model):
    unique_boolean = UniqueBooleanField()

    def __unicode__(self):
        return str(self.unique_boolean)

Source: stackoverflow.com

Similar codes

0 vote310 views1 answer
How to extract zip file in jupyter notebook
Python
0 vote294 views1 answer
Render django views
Python
10 votes297 views5 answers
Progress bar in cmd python
Python
0 vote281 views1 answer
Get type name python
Python
1 vote255 views2 answers
How to put iput python
Python
0 vote286 views1 answer
How to access a file from root folder in python project
Python
3 votes291 views1 answer
No module named 'django.core.urlresolvers'
Python Django
1 vote289 views1 answer
Python remove first item in tuple
Python
0 vote260 views1 answer
Bar Plot Seaborn with No Error Bars
Python
3 votes258 views1 answer
AttributeError: module 'librosa' has no attribute 'display' site:stackoverflow.com
Python