strong parameters not accepting array

Question

I have this in my view which is a multiselect checkbox Model ``` class User < ActiveRecord::Base has_many :user_roles, :dependent => :destroy accepts_nested_attributes_for :user_roles, :allow_destroy => true has_many :roles, :through => :user_roles end ``` view ``` <%= check_box_tag 'user[role_ids][]', role.id, user.blank? ? nil : user.roles.include?(role) ,id: dom_id(role)%> ``` the strong parameters for this is written as ``` def user params.require(:user).permit(:first_name,{:role_ids => []}) end ``` But on create it says ``` Processing by Admin::UsersController#create as HTML Parameters: {"utf8"=>"✓", "authenticity_token"=>"+y8iWya5KIILqS0embEUEZuClycXq0O9Q4pA+MnbM0g=", "user"=>{"first_name"=>"", "last_name"=>"", "email"=>"a@loclahost.com", "language"=>"en", "access_level_id"=>"1", "role_ids"=>["", "1", "", "5", "", "", ""], "password"=>"[FILTERED]", "password_confirmation"=>"[FILTERED]"}, "commit"=>"Create user"} Unpermitted parameters: role_ids Unpermitted parameters: role_ids U…

Accepted Answer

Answering myself, I got it working not directly, but the below method from the Strong Parameters issues discussion helped me in converting a normal parameter to a whitelisted one.

```
def user_params
  params.require(:user).permit(:first_name).tap do |whitelisted|
    whitelisted[:role_ids] = params[:user][:role_ids]
  end
end
```

strong parameters not accepting array

Solution

Problem