I can't save record in sqlite Rails - ruby-on-rails

Question

I try save record on database, in pivot table but I have a error(screen) if I write #video.category_ids = 1 it works but category id = 1 in database
Below I put my code if you neeed more information please write.
videos_controller.rb
class VideosController < ApplicationController
layout 'master'
before_action :chceck_login
def index
#videos = Video.sortASC
end
def new
#categories = Category.all
end
def create
#video = Video.new(video_params)
#video.category_ids = [video_params]
if #video.save
flash[:notice] = 'The movie has been added successfuly'
redirect_to(:action => 'index')
else
#categories = Category.all
render('new')
end
end
def show
end
def edit
end
def delete
end
private
def video_params
params.require(:video).permit(:title, :url, :description, category_attributes: [:id]).merge(user_id: session[:user_id])
end
end
_form_html.erb
<div class="input-group mb-3">
<div class="input-group-prepend">
<span class="input-group-text" id="basic-addon1"><i class="fas fa-tag"></i></span>
</div>
<%= f.text_field :title, placeholder: 'Title', :class => 'form-control', :id => 'title' %>
</div>
<div class="input-group mb-3">
<div class="input-group-prepend">
<span class="input-group-text" id="basic-addon1"><i class="fas fa-link"></i></span>
</div>
<%= f.text_field :url, placeholder: 'URL', :class => 'form-control', :id => 'url' %>
</div>
<div class="input-group mb-3">
<div class="input-group-prepend">
<span class="input-group-text" id="basic-addon1"><i class="fas fa-edit"></i></span>
</div>
<%= f.text_area :description, placeholder: 'Description', rows: 5, :class => 'form-control', :id => 'description' %>
</div>
<div class="input-group mb-3">
<div class="input-group-prepend">
<span class="input-group-text" id="basic-addon1"><i class="fas fa-sitemap"></i></span>
</div>
<%= f.select(:category_id, #categories.map{|t| [t.name, t.id]}, {}, :multiple => true, :class => 'custom-select') %>
</div>
video.rb
class Video < ApplicationRecord
belongs_to :user
has_and_belongs_to_many :categories
scope :sortASC, lambda{order("videos.created_at ASC")}
end
new.html.erb
<% #page_title = 'Add Film' %>
<div class='container'>
<div class='row'>
<div class='col s-6'>
<div class="jumbotron jumbotron-fluid bg-info">
<div class="container">
<h1 class="display-4 text-center">ADD NEW FILM <i class="fas fa-plus"></i></h1>
<p class="lead">This is a modified jumbotron that occupies the entire horizontal space of its parent.</p>
</div>
</div>
</div>
<div class='col s-6'>
<%= form_for(:video, :url => {:action => 'create'}) do |f| %>
<%= render(:partial => 'form', :locals => {:f => f}) %>
<%= submit_tag('Add Film', :class => 'btn btn-primary float-right') %>
<% end %>
</div>
</div>
</div>
Error
https://imgur.com/7P4WpMU
If you want I have put my project on Github.

Answer 1

I would suggest the following changes:
In _form.html.erb pluralize the name of the select, i.e. change
<%= f.select(:category_id, #categories.map{|t| [t.name, t.id]}, {}, :multiple => true, :class => 'custom-select') %>
to
<%= f.select(:category_ids, #categories.map{|t| [t.name, t.id]}, {}, :multiple => true, :class => 'custom-select') %>
In videos_controller.rb change
def video_params
params.require(:video).permit(:title, :url, :description, category_attributes: [:id]).merge(user_id: session[:user_id])
end
to
def video_params
params[:video][:category_ids].reject!(&:blank?) unless params[:video][:category_ids].nil?
params.require(:video).permit(:title, :url, :description, category_ids: []).merge(user_id: session[:user_id])
end
Also in videos_controller.rb remove
#video.category_ids = [video_params]
to leave things to the constructor
Regarding 2. I am not 100% sure about the exact solution, maybe you should also reject the empty id you have in your parameters (according to the provided screenshot, use .reject!(&:blank?) for that) - for analyzing further problems check the output of the video_params function before passing it to the constructor - it basically should look like a hash representation of the expected object.
edit Updated the change proposal for 2. regarding category_ids