Implication for Q object.

[Bartłomiej Biernacki]

Starting with Django 2.2 we have CheckConstraints where we can use Q objects to create Database level checks.
I found that it's common to have some conditional check constrains i.e. "if some field_a has value 'x' then field_b have value greater than 0".
In basic logic we can write this as p => q which can be translated to ~p or q.
Using Django Q we can write this constraints as ~Q(field='x') or Q(field_b__gt=0).
While this serves the purpose it might be more readable if we will have a dedicated "implication" function.

I propose to use binary operator >> for that purpose, so in Django Q we could write a Q(field='x') >> Q(field_b__gt=0) which in mine opinion looks much more readable and can encourage people to use more database level constratins in their projects

I have provided a patch with this functionality: ​https://github.com/django/django/pull/11978
If this will be accepted I will add documentation to it.

[Mariusz Felisiak]

Thanks for this ticket, however using a >> operator for implications sounds extremely confusing for me and as you pointed it can be described by ~p or q. I don't think that we need a separate API for this. You can start a discussion on DevelopersMailingList if you don't agree.