Still getting NotNullViolation despite belongs_to :foo, optional: true

Question

I have a has_one and belongs_to association, like so:

# teacher.rb
has_one: :student

and

# student.rb 
belongs_to :teacher, optional: true

but when I try to create a student without a teacher...

a = Student.new()
a.save!
ActiveRecord::NotNullViolation: PG::NotNullViolation: ERROR:  null value in column "teacher_id" violates not-null constraint

Which doesn't make sense, since I have optional: true. I have tried rake db:drop db:create db:migrate db:seed numerous times but still the same error

Answer 1

Thanks to @dbugger and @Daniel Sindrestean and with help from another forum I see it's as simple as going into the existing migration file and changing null: false to null: true. Then remake the database. Or run a migration to change null:true if working on an existing app. Either way, null: false needs to be null: true

Also, from @max's comment:

The optional and its inverse required options for belongs_to just control if the association adds a presence_of validation. That really does not have anything to with a database driver error