Rails Simple Form Association submission not updating - ruby-on-rails

Question

I have a problem with has_many relationships setting up forms that do not update the values after submission.
Example
Upon submission of a new character, vn_id does not get updated and in Rails Consoles when I try to check for characters in a Vn, it returns empty.
I am trying to set up a form for characters which belongs to Vn which will be linked through the association but upon submission, it is not linked to Vn.
class Character < ActiveRecord::Base
validates :name, :presence => true
validates :summary, :presence => true
belongs_to :vn
end
class Vn < ActiveRecord::Base
has_many :characters
validates :name, presence: true
accepts_nested_attributes_for :characters
end
Form to create a new Character
<%= simple_form_for #character do |f| %>
<div class="col-lg-12">
<%= f.input :summary,input_html: {style: "height:150px;"} %>
</div>
<div class="col-lg-12">
<%= f.association :vn, as: :check_boxes %>
</div>
<%= f.button :submit , class: "btn btn-primary" %>
<% end %>
Controllers
class CharactersController < ApplicationController
def show
#character = Character.find(params[:id])
end
def new
#character = Character.new
end
def create
#character = Character.new(char_params)
if #character.save
else
render :action=>"new"
end
end
private
def char_params
params.require(:character).permit(:name, :summary,:voiceactor,:vn_name,vn_id: [])
end
end
class VnsController < ApplicationController
def show
#vn = Vn.find(params[:id])
end
def new
#vn = Vn.new
end
def create
#vn = Vn.new(vn_params)
if #vn.save
else
render :action=>"new"
end
end
private
def vn_params
def vn_params
params.require(:vn).permit(:name, :summary,:genre,:developer,:rating,vn_id: [])
end
end
end
Submission unpermitted vn_id
Parameters: {"utf8"=>"✓", "authenticity_token"=>"O2s6GVs77GGUMC5u3eZ9ebv/0l5u0MwP44yS8WGCQnjgwSgHfkbCmhEOUo6WKIMSMo5IfDuNYtMzyphnT/5cwQ==", "character"=>{"name"=>"2222", "voiceactor"=>"111", "summary"=>"one two tthee", "vn_id"=>"32"}, "commit"=>"Create Character"}
Unpermitted parameter: vn_id
(0.1ms) begin transaction
SQL (0.6ms) INSERT INTO "characters" ("name", "summary", "voiceactor", "created_at", "updated_at") VALUES (?, ?, ?, ?, ?) [["name", "2222"], ["summary", "one two tthee"], ["voiceactor", "111"], ["created_at", "2015-10-23 10:34:00.285447"], ["updated_at", "2015-10-23 10:34:00.285447"]

Answer 1

The problem is you're trying to permit an array for a singular association.
The f.association input is for your belongs_to association, so why would it allow multiple records?
You can even see how this works here:
The above are methods only for has_many
In short, they don't exist for belongs_to
Thus, when you call f.association :vn, you're populating an attribute vn_id which can then be associated in your database.
The only time you'd have vn_ids is if you used has_many etc.
This means...
def character_params
params.require(:character).permit(:vn_id)
end
with
f.association :vn
... should work

Answer 2

Somehow, changing vn_id: [] in CharactersController back to :vn_id worked.