Using checkboxes to pass multiple strings to array in migration with ruby - ruby

Question

Im looking to have a user create a post where they specify what instruments they play. There should be a checkbox for each instrument so the user can select the ones that apply to the post. I was able to display the instruments and their checkboxes in the post creation but I cannot figure out how to save them to the post. I get error ActiveRecord::AssociationTypeMismatch.
Displaying all instruments and passing integers for each (Id like to pass strings)
<% Instrument.all.each do |instrument| %>
<%= check_box_tag "post[instruments][]", instrument.id %>
<%= instrument.name %> <br>
<% end %>
<div class="actions">
<%= form.submit %>
</div>
Migration to receive array of integers
class AddTagsToPost < ActiveRecord::Migration[5.2]
def change
add_column :posts, :instruments, :integer, array: true, :default => []
end
end
schema.rb
create_table "instruments", force: :cascade do |t|
t.string "name"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
end
create_table "posts", force: :cascade do |t|
t.bigint "category_id"
t.string "title"
t.text "content"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
t.bigint "account_id"
t.integer "instruments", default: [], array: true
t.index ["account_id"], name: "index_posts_on_account_id"
t.index ["category_id"], name: "index_posts_on_category_id"
end
post.rb model
class Post < ApplicationRecord
belongs_to :category
belongs_to :account
has_many :instruments
validates :title, presence: true, length: { minimum: 3 }
validates :content, presence: true, length: { maximum: 500 }
end
instrument.rb model
class Instrument < ApplicationRecord
belongs_to :posts, optional: true
end
Private end of the posts_controller.rb
private
# Use callbacks to share common setup or constraints between actions.
def set_post
#post = Post.find(params[:id])
end
# Only allow a list of trusted parameters through.
def post_params
params.fetch(:post, {}).permit(:title, :content, :category_id, instruments:[])
end
end