Create SitesHelper with delivery_map_accepted_mime_types method

app/helpers/sites_helper.rb

@@ -0,0 +1,10 @@
+# frozen_string_literal: true
+
+module SitesHelper
+  def delivery_map_accepted_mime_types
+    Site.validators_on(:delivery_map).find { |v| v.is_a?(ActiveStorageValidations::ContentTypeValidator) }
+      .options[:in].map { |f| Mime[f].to_s }
+      .uniq
+      .join(", ")
+  end
+end

app/models/site.rb

@@ -8,7 +8,7 @@ class Site < ApplicationRecord
 
   has_one_attached :delivery_map
 
-  validates :delivery_map, content_type: %i[png jpg jpeg pdf gif]
+  validates :delivery_map, content_type: %i[png jpg jpeg gif pdf]
 
   geocoded_by :address
   after_validation :geocode

app/views/sites/_form.html.erb

@@ -71,7 +71,7 @@
       <%= f.label :delivery_map, class: "form-label" %>
       <%= f.file_field :delivery_map,
                        class: "form-control",
-                       accept: "image/png, image/jpeg, image/gif, application/pdf" %>
+                       accept: delivery_map_accepted_mime_types %>
       <% if @site.delivery_map.attached? && @site.persisted? %>
         <%= image_tag @site.delivery_map.representation(resize_to_limit: [200, 200]), class: "ms-0 mt-2" %>
       <% end %>

spec/helpers/sites_helper_spec.rb

@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+require "rails_helper"
+
+RSpec.describe SitesHelper do
+  describe "delivery_map_accepted_mime_types" do
+    it { expect(helper.delivery_map_accepted_mime_types).to eq("image/png, image/jpeg, image/gif, application/pdf") }
+  end
+end