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			31 lines
		
	
	
		
			668 B
		
	
	
	
		
			Python
		
	
	
	
	
	
			
		
		
	
	
			31 lines
		
	
	
		
			668 B
		
	
	
	
		
			Python
		
	
	
	
	
	
| from django.db import models
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| 
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| 
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| class Person(models.Model):
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|     name = models.CharField(max_length=200)
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| 
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| 
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| class Movie(models.Model):
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|     title = models.CharField(max_length=200)
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|     director = models.ForeignKey(Person, models.CASCADE)
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| 
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| 
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| class Event(models.Model):
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|     pass
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| 
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| 
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| class Screening(Event):
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|     movie = models.ForeignKey(Movie, models.CASCADE)
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| 
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| 
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| class ScreeningNullFK(Event):
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|     movie = models.ForeignKey(Movie, models.SET_NULL, null=True)
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| 
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| 
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| class Package(models.Model):
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|     screening = models.ForeignKey(Screening, models.SET_NULL, null=True)
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| 
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| 
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| class PackageNullFK(models.Model):
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|     screening = models.ForeignKey(ScreeningNullFK, models.SET_NULL, null=True)
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