Validate Active Storage Attachements

example.md

class Webpage < ApplicationRecord
  has_one_attached :open_graph_image

  validate :open_graph_image_content_type
  validate :open_graph_image_size

  private

  def open_graph_image_content_type
    return if open_graph_image.content_type.nil?
    permitted_content_type = %w[JPEG PNG]
    content_type = open_graph_image.content_type.split("/").last.upcase
    if !permitted_content_type.include? content_type
      errors.add(:open_graph_image, "should be a an JPEG or PNG")
    end
  end

  def open_graph_image_size
    return if open_graph_image.byte_size.nil?
    if open_graph_image.byte_size > 2000000
      errors.add(:open_graph_image, "cannot be larger than 2MB")
    end
  end
end

<%= form_with model: @webpage do |form| %>
  <%= form.label :open_graph_image, class: "form-label" %>
  <!--  Use the accept attribute for client side validation -->
  <%= form.file_field :open_graph_image, accept: "image/png, image/jpeg" %>
  <%= form.submit "Share The Link", class: "btn btn-primary" %>  
<% end %>