Question

What is the difference between:

t.boolean :test, :default => true

and

t.boolean :test, :null => true

and

t.boolean :test, :default => true, :null => true

EDIT

Does the following make any sense?

t.boolean :test, :default => true, :null => false

Answer 1

“null” means “are you allowed to enter a null value in this column”?

Whereas “default” means “if there is a null value in this column … then use this default value instead”

So, for your examples:

t.boolean :test, :default => true

“this boolean column will insert a true if you don’t bother setting a value for it”

t.boolean :test, :null => true

“this boolean column will let you set it to true, false or null – and it will stay the way you set it”

t.boolean :test, :default => true, :null => true

“this boolean column will let you set it to true, false or null… but if you set it to null it will automatically be set to true”