django filter depeding on character count of the item

I have two models such that

class Employer(models.Model):
    code = models.CharField(null=False,blank=False,default="")

class JobTitle(models.Model):
    employer = models.ForeignKey(Employer,unique=False,null=False,default=0)
    name = models.CharField(max_length=1000,null=False,default="")
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and I would like to get all employers whose jobtitle name is less than X chracters. How can I achive this in Django ?

Thanks

---

Use extra:

Emp.objects.extra(select={'name_length': 'LENGTH(`name`)'},
                  where=['name_length < 24'])

or raw:

Emp.objects.raw('SELECT * FROM myapp_emp WHERE LENGTH(`name`) < 24')