Two collection_select that save as two different records

Question

I have this:

<%= f.collection_select :category_ids, Category.all, :id, :name, {} %>

inside my form and it creates the record no problem, however I'm lost on how to make more two or more records inside the same form, all the things I try either just create the one record or none at all. I found this solution, which I analyzed and was sure was gonna work (altough I don't really get on why it uses nil):

<%= f.fields_for :category_ids do |category| %>

  <%= category.collection_select(nil, Category.all, :id, :name,
    {include_blank: "---", selected: 0},
    {id: :event_category_id_1}) %>

  <%= category.collection_select(nil, Category.all, :id, :name,
    {include_blank: "---", selected: 0},
    {id: :event_category_id_2}) %>

<% end %>

but this time it creates no record at all.

Here are my models:

class Event < ApplicationRecord

  has_many :categorizations
  has_many :categories, through: :categorizations
  accepts_nested_attributes_for :categorizations

end

class Category < ApplicationRecord

  has_many :categorizations
  has_many :events, through: :categorizations

end

class Categorization < ApplicationRecord

  belongs_to :event
  belongs_to :category

end

Answer 1

You want to assign more than one Category to your Model? Post your model so we can figure what's going wrong when storing it.

Adding multiple: true (and size: 5) will expand your select field and by holding ctrl/cmd you can select multiple entries.

<%= f.collection_select :category_ids, Category.all, :id, :name, {multiple: true, size: 5} %>