Rails: How can i set empty array with current parameters

Question

my application want to send empty array if check_box_tag is unchecked

This is my hidden_field_tag code

<%= hidden_field_tag('user[roles][]') %>

now i get parameter

"user"=>{"roles"=>[""]}

i want to instead with

 "user"=>{"roles"=>[]}

please guides

Answer 1

You cant prevent rails from assigning "" as default value but you can remove empty strings from an array in the controller like this:

@arr = params["user"]["roles"].map{ |x|
  x unless x.empty?
  nil if x.empty?
}.compact

The map replaces empty strings with nil and compact removes the nil values from the array.

Answer 2

<%= hidden_field_tag('user[roles][]', nil) %>