class Employee(models.Model):
    name = models.CharField(max_length=255)

class Attendance(models.Model):
    date = models.DateField()
    employee = models.ForeignKey(Employee, related_name='attendance')

class Salary(models.Model):
    salary = models.DecimalField(max_digits=20, decimal_places=0)
    employee = models.ForeignKey(Employee, related_name='salary')

class Salary(DetailView):
    context_object_name = 'salary_detail'
    model = models.Salary
    template_name = 'system/salary_detail.html'

class Employee(models.Model):
    name = models.CharField(max_length=255)

class Attendance(models.Model):
    date = models.DateField()
    employee = models.ForeignKey(Employee, related_name='attendance')

class Salary(models.Model):
    from_date = models.DateField()
    to_date = models.DateField()
    salary = models.DecimalField(max_digits=20, decimal_places=0)
    employee = models.ForeignKey(Employee, related_name='salary')


employee.attendance.filter(date__gte=employee.salary.from_date, date__lte=employee.salary.to_date).values('dates')