Complex query in Django where subquery exists with relation ManyToMany

Question

I'm writing a query in Django ORM that return all persons that have a skill set.

For example: all persons with "language == English" and "role == Manager"

An example of the SQL query can be as follows:

select person.name 
  from person 
 where exists
        (select * 
          from skill 
         where skill.id = person.id
           and ((skill.type = 'language' and skill.value = 'English') and \ 
           (skill.type = 'role' and skill.value = 'Manager')))

Well, I have this structure class model in Django

class Person(models.Model):
    name = models.CharField(max_length=60)
    age = models.IntegerField()

class Skill(models.Model):
    type = models.CharField(max_length=20)
    value = models.CharField(max_length=30)
    persons = models.ManyToManyField(Person)

Records on table Person

| name   | age |
|--------|-----|
| Arnold | 23  |
| Bull   | 24  | 
| John   | 25  |

Records on table Skill

| type     | value      | persons      |
|----------|------------|--------------|
| role     | Customer   | John, Bull   |
| role     | Manager    | John         |
| language | English    | Bull, Arnold |
| language | Portuguese | John, Bull   |

Use cases:

• On filter role Customer and language English should return person Bull.
• On filter role Customer and language Portuguese should return persons John and Bull.
• On filter role Manager and language English should return no results.

Is it possible to build a query that attend these use cases?

Answer 1

This should work:

Person.objects.filter(skill__type='role', skill__value='Customer')

You can access to the related objects attributes with '__' notation.