Validates acceptance always fails - ruby-on-rails

Question

No other answers I found on that issue helped me.
I have a terms and conditions box and want to validate if it's checked on creation.
In my model:
validates :terms_and_conditions, :on => :create, acceptance: true, :allow_nil => false
In my view:
<%= f.check_box(:terms_and_conditions )%>
It always fails, no matter if the check_box is checked or not. I think it never actually sets the field and the problem is in my view, but I can't find it.
Log when submitting the form.
Processing by Users::RegistrationsController#create as HTML
Parameters: {"utf8"=>"✓", "authenticity_token"=>"xNNmGTWSV4hkj0rrlZeOq+AiTlJ9sc9+cAT1Sy0bjhc=", "user"=>{"email"=>"sdasdr#gmail.com", "password"=>"[FILTERED]", "password_confirmation"=>"[FILTERED]", "name"=>"", "surname"=>"", "country_id"=>"", "language"=>"", "description"=>"", "register_as_company"=>"1", "terms_and_conditions"=>"1"}, "commit"=>"Sign up"}
Unpermitted parameters: name, surname, country_id, language, description, register_as_company, terms_and_conditions
[1m[35m (0.1ms)[0m begin transaction
[1m[36mUser Exists (0.3ms)[0m [1mSELECT 1 AS one FROM "users" WHERE "users"."email" = 'sdasdr#gmail.com' LIMIT 1[0m
[1m[35m (0.1ms)[0m rollback transaction
[1m[36mCountry Load (0.2ms)[0m [1mSELECT "countries".* FROM "countries"[0m
Rendered devise/registrations/new.html.erb within layouts/application (6.1ms)
Rendered layouts/_auth_widget.html.erb (1.1ms)
Completed 200 OK in 127ms (Views: 22.8ms | ActiveRecord: 0.7ms)

Answer 1

You have not permitted terms_and_conditions attribute to be saved in the database. If you notice the server logs closely,
Unpermitted parameters: name, surname, country_id, language, description, register_as_company, terms_and_conditions
there are multiple attributes which are not permitted so all of them are not getting saved in database. terms_and_conditions goes as nil and results in error as the value submitted via form is ignored (because of unpermitted status).
This is related to Rails 4 Strong Parameters concept wherein only those attributes would be saved in database which are whitelisted/ permitted.
Checkout the information on Strong Parameters
Also, as per the server log I noticed that these attributes are part of User model which is a Devise model. Permitting attributes for Devise can be done in different ways,
you can refer to SO Question: Rails devise simple form not saving all fields for this.