As we know Ruby language has only two false values false and nil. Any other value in Ruby treated as true.

But sometimes we need to pass true/false values into params from checkboxes or from custom url param into our API endpoint. Our url may looks like /products.json?simple_view=false then we get our param’s value as String

> params[:simple_view]
=> "false"

That will prevents us to build condition like

if params[:simple_view]

in that case we will face unexpected behavior. Yes we can describe condition as

if params[:simple_view] != "false"

and that will work until someone pass simple_view=f or simple_view=off. We can extend our condition and soon it will looks ugly.

On the other hand when we’re using checkbox on our HTML page and that checkbox is binded to one of columns of the Model, Rails treats “off” and “0” values as false. Rails knows what exactly do we mean by passing values like these becase of FALSE_VALUES list.

> ActiveRecord::ConnectionAdapters::Column::FALSE_VALUES
=> #<Set: {false, 0, "0", "f", "F", "false", "FALSE", "off", "OFF"}>

Now we can describe our condition as:

unless ActiveRecord::ConnectionAdapters::Column::FALSE_VALUES.include?(params[:simple_view])

It’s looks quite verbose so we can extract it into helper method.