gistfile1.txt

# In production mode
2.1.0 :001 > p = { a: 1, b: 2, c: 3 }
 => {:a=>1, :b=>2, :c=>3}
2.1.0 :002 > params = ActionController::Parameters.new(p)
 => {"a"=>1, "b"=>2, "c"=>3}
2.1.0 :003 > params.permit(:a)
 => {"a"=>1}
2.1.0 :004 >

# In development mode
2.1.0 :001 > p = { a: 1, b: 2, c: 3 }
 => {:a=>1, :b=>2, :c=>3}
2.1.0 :002 > params = ActionController::Parameters.new(p)
 => {"a"=>1, "b"=>2, "c"=>3}
2.1.0 :003 > params.permit(:a)
Unpermitted parameters: b, c
 => {"a"=>1}
2.1.0 :004 >