Django get all objects whose many to many filed contains a filter

I have 3 models:

City: indicating a city
Titles: indicating job titles
Contacts: indicating people. A person can have multiple titles and multiple cities

Now, given an city object and a title object, I want to query for all people that have those objects in their instance. Basically something like "All Lawyers in NY".

class City(models.Model):
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    name=models.CharField(max_length=40)
    state=models.CharField(max_length=15)

class Title(models.Model):
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    title_name=models.CharField(max_length=40)

class Contact(models.Model):
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    name_surname = models.CharField(max_length=60)
    title = models.ManyToManyField(Title)
    city = models.ManyToManyField(City)

Solution

You can filter with:

Contract.objects.filter(
    title__title_name='Lawyer',
    city__name='NY'
)

But, the modeling does not make much sense, since here a Contract relates to multiple Titles and multiple Citys, but it is unclear what title belongs to what city.

Imagine that we have a person who is a software engineer in New York, and a barman in Los Angeles, then the modelling can not make a distinction between this person, and a person who is a barman in New York, and a software engineer in Los Angeles.

We can model this with a Person and a Contract that refers to a city and a title, so:

class City(models.Model):
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    name=models.CharField(max_length=40)
    state=models.CharField(max_length=15)

class Title(models.Model):
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    title_name=models.CharField(max_length=40)

class Person(models.Model):
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=Falsee)
    name_surname = models.CharField(max_length=60)

class Contact(models.Model):
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    person = models.ForeignKey(Person, on_delete=models.CASCADE)
    title = models.ForeignKey(Title, on_delete=models.CASCADE)
    city = models.ForeignKey(City, on_delete=models.CASCADE)

Then we can determine such person with:

Person.objects.filter(
    contract__title__title_name='Lawyer',
    contract__city__name='NY'
)

Then we thus retrieve all Persons that have at least a Contract with lawyer as title_name, and NY as name for the city.