1from django.core.exceptions import ValidationError 

2from django.db import models 

3 

4 

5class SingletonModel(models.Model): 

6 class Meta: 

7 abstract = True 

8 

9 def save(self, *args, **kwargs): 

10 self.pk = 1 

11 super(SingletonModel, self).save(*args, **kwargs) 

12 

13 def delete(self, *args, **kwargs): 

14 pass 

15 

16 @classmethod 

17 def load(cls): 

18 obj, created = cls.objects.get_or_create(pk=1) 

19 return obj 

20 

21 

22class SiteSetting(SingletonModel): 

23 start_date = models.DateField() 

24 end_date = models.DateField() 

25 child_family_start_date = models.DateField("Child family support/participation start date", null=True) 

26 child_family_end_date = models.DateField("Child family support/participation end date", null=True) 

27 

28 def clean(self): 

29 if self.start_date and self.end_date and \ 

30 self.start_date > self.end_date: 

31 raise ValidationError( 

32 'Start Date shouldn\'t be greater then End Date' 

33 ) 

34 if self.child_family_start_date and self.child_family_end_date and \ 

35 self.child_family_start_date > self.child_family_end_date: 

36 raise ValidationError( 

37 'Start Date shouldn\'t be greater then End Date' 

38 ) 

39 

40 def __str__(self): 

41 return 'Site Settings'