Show attachments in HTML

app/controllers/attachments_controller.rb

@@ -0,0 +1,22 @@
+# frozen_string_literal: true
+
+class AttachmentsController < ApplicationController
+  skip_forgery_protection
+
+  def show
+    if (key = decode_verified_key)
+      send_data ActiveStorage::Blob.service.download(key[:key]), content_type: key[:content_type], disposition: key[:disposition]
+    else
+      head :not_found
+    end
+  rescue Errno::ENOENT
+    head :not_found
+  end
+
+  private
+
+  def decode_verified_key
+    key = ActiveStorage.verifier.verified(params[:encoded_key], purpose: :blob_key)
+    key&.deep_symbolize_keys
+  end
+end

app/views/messages/_attachment.html.erb

@@ -0,0 +1,49 @@
+<% if attachment.content_type&.start_with?('image/') %>
+  <div class="space-y-2">
+    <div class="flex items-center gap-3 text-sm">
+      <svg class="w-4 h-4 text-gray-400 dark:text-gray-500 flex-shrink-0" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+        <path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M4 16l4.586-4.586a2 2 0 012.828 0L16 16m-2-2l1.586-1.586a2 2 0 012.828 0L20 14m-6-6h.01M6 20h12a2 2 0 002-2V6a2 2 0 00-2-2H6a2 2 0 00-2 2v12a2 2 0 002 2z"></path>
+      </svg>
+      <%= link_to attachment.filename.to_s, rails_blob_path(attachment, disposition: "attachment"), class: "text-red-600 dark:text-red-400 hover:text-red-800 dark:hover:text-red-300 font-medium" %>
+      <span class="text-gray-500 dark:text-gray-400">(<%= number_to_human_size(attachment.byte_size) %>)</span>
+    </div>
+    <%= image_tag rails_blob_path(attachment), class: "max-w-full h-auto rounded border border-gray-300 dark:border-gray-600", alt: attachment.filename.to_s %>
+  </div>
+<% elsif attachment.content_type&.start_with?('text/') %>
+  <div class="space-y-2">
+    <div class="flex items-center gap-3 text-sm">
+      <svg class="w-4 h-4 text-gray-400 dark:text-gray-500 flex-shrink-0" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+        <path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 12h6m-6 4h6m2 5H7a2 2 0 01-2-2V5a2 2 0 012-2h5.586a1 1 0 01.707.293l5.414 5.414a1 1 0 01.293.707V19a2 2 0 01-2 2z"></path>
+      </svg>
+      <%= link_to attachment.filename.to_s, rails_blob_path(attachment, disposition: "attachment"), class: "text-red-600 dark:text-red-400 hover:text-red-800 dark:hover:text-red-300 font-medium" %>
+      <span class="text-gray-500 dark:text-gray-400">(<%= number_to_human_size(attachment.byte_size) %>, <%= attachment.content_type %>)</span>
+    </div>
+    <% if attachment.byte_size < 100_000 %>
+      <pre class="whitespace-pre-wrap font-mono text-sm text-gray-800 dark:text-gray-300 bg-gray-100 dark:bg-gray-800 p-4 rounded border border-gray-300 dark:border-gray-600 overflow-x-auto"><%= attachment.download %></pre>
+    <% end %>
+  </div>
+<% elsif attachment.content_type == 'application/pdf' %>
+  <div class="flex items-center gap-3 text-sm">
+    <svg class="w-4 h-4 text-red-500 dark:text-red-400 flex-shrink-0" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+      <path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M7 21h10a2 2 0 002-2V9.414a1 1 0 00-.293-.707l-5.414-5.414A1 1 0 0012.586 3H7a2 2 0 00-2 2v14a2 2 0 002 2z"></path>
+    </svg>
+    <%= link_to attachment.filename.to_s, rails_blob_path(attachment, disposition: "attachment"), class: "text-red-600 dark:text-red-400 hover:text-red-800 dark:hover:text-red-300 font-medium" %>
+    <span class="text-gray-500 dark:text-gray-400">(<%= number_to_human_size(attachment.byte_size) %>, PDF)</span>
+  </div>
+<% elsif attachment.content_type&.match?(/zip|tar|gzip|compress|bzip|lha/) %>
+  <div class="flex items-center gap-3 text-sm">
+    <svg class="w-4 h-4 text-gray-400 dark:text-gray-500 flex-shrink-0" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+      <path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M5 19a2 2 0 01-2-2V7a2 2 0 012-2h4l2 2h4a2 2 0 012 2v1M5 19h14a2 2 0 002-2v-5a2 2 0 00-2-2H9a2 2 0 00-2 2v5a2 2 0 01-2 2z"></path>
+    </svg>
+    <%= link_to attachment.filename.to_s, rails_blob_path(attachment, disposition: "attachment"), class: "text-red-600 dark:text-red-400 hover:text-red-800 dark:hover:text-red-300 font-medium" %>
+    <span class="text-gray-500 dark:text-gray-400">(<%= number_to_human_size(attachment.byte_size) %>, Archive)</span>
+  </div>
+<% else %>
+  <div class="flex items-center gap-3 text-sm">
+    <svg class="w-4 h-4 text-gray-400 dark:text-gray-500 flex-shrink-0" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+      <path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M15.172 7l-6.586 6.586a2 2 0 102.828 2.828l6.414-6.586a4 4 0 00-5.656-5.656l-6.415 6.585a6 6 0 108.486 8.486L20.5 13"></path>
+    </svg>
+    <%= link_to attachment.filename.to_s, rails_blob_path(attachment, disposition: "attachment"), class: "text-red-600 dark:text-red-400 hover:text-red-800 dark:hover:text-red-300 font-medium" %>
+    <span class="text-gray-500 dark:text-gray-400">(<%= number_to_human_size(attachment.byte_size) %><% if attachment.content_type %>, <%= attachment.content_type %><% end %>)</span>
+  </div>
+<% end %>

app/views/messages/_message.html.erb

@@ -23,4 +23,13 @@
   <div class="px-6 py-4">
     <pre class="whitespace-pre-wrap font-mono text-sm text-gray-800 dark:text-gray-300 leading-relaxed"><%= message.body %></pre>
   </div>
+
+  <% if message.attachments.attached? %>
+    <div class="border-t border-gray-200 dark:border-gray-700 px-6 py-4 bg-gray-50 dark:bg-gray-900">
+      <h3 class="text-sm font-medium text-gray-700 dark:text-gray-300 mb-3">Attachments (<%= message.attachments.count %>)</h3>
+      <div class="space-y-4">
+        <%= render partial: 'messages/attachment', collection: message.attachments %>
+      </div>
+    </div>
+  <% end %>
 </div>

config/routes.rb

@@ -3,6 +3,8 @@
   get '/:list_name/:list_seq', to: 'messages#show'
   get '/:list_name/', to: 'messages#index'
 
+  get '/attachments/:encoded_key/*filename' => 'attachments#show', as: :attachment
+
   # Define your application routes per the DSL in https://guides.rubyonrails.org/routing.html
 
   # Reveal health status on /up that returns 200 if the app boots with no exceptions, otherwise 500.

lib/active_storage/service/database_service.rb

@@ -33,6 +33,34 @@ def exist?(key)
 
     private
 
+    def private_url(key, expires_in:, filename:, content_type:, disposition:, **)
+      content_disposition = content_disposition_with(type: disposition, filename: filename)
+      verified_key_with_expiration = ActiveStorage.verifier.generate(
+        {
+          key: key,
+          disposition: content_disposition,
+          content_type: content_type,
+          service_name: name
+        },
+        expires_in: expires_in,
+        purpose: :blob_key
+      )
+
+      if url_options.blank?
+        raise ArgumentError, "Cannot generate URL for #{filename} using Database service, please set ActiveStorage::Current.url_options."
+      end
+
+      url_helpers.attachment_url(verified_key_with_expiration, filename: filename, **url_options)
+    end
+
+    def url_helpers
+      @url_helpers ||= Rails.application.routes.url_helpers
+    end
+
+    def url_options
+      ActiveStorage::Current.url_options
+    end
+
     def service_name
       'Database'
     end

test/controllers/messages_controller_test.rb

@@ -2,7 +2,7 @@
 
 class MessagesControllerTest < ActionDispatch::IntegrationTest
   setup do
-    @message = messages(:one)
+    @message = messages(:message1)
   end
 
   test "should get index" do

test/fixtures/active_storage/attachments.yml

@@ -0,0 +1,5 @@
+attachment2:
+  name: attachments
+  record_type: Message
+  record: message2
+  blob: blob2

test/fixtures/active_storage/blobs.yml

@@ -0,0 +1,7 @@
+blob2:
+  key: 3mj2l9tdw1nb531oajdax3r7vylh
+  filename: 1.patch
+  content_type: text/x-diff
+  metadata: '{"identified":true,"analyzed":true}'
+  byte_size: 5
+  service_name: local

test/fixtures/active_storage/file_blobs.yml

@@ -0,0 +1,3 @@
+file_blob2:
+  key: 3mj2l9tdw1nb531oajdax3r7vylh
+  data: Hello

test/fixtures/messages.yml

@@ -1,15 +1,15 @@
 # Read about fixtures at https://api.rubyonrails.org/classes/ActiveRecord/FixtureSet.html
 
-one:
-  subject: MyString
-  from: MyString
-  body: MyText
+message1:
+  subject: Mail1
+  from: From1
+  body: Body1
   list_id: 1
   list_seq: 123
 
-two:
-  subject: MyString
-  from: MyString
-  body: MyText
+message2:
+  subject: Mail2
+  from: From2
+  body: Body2
   list_id: 2
   list_seq: 234

test/system/messages_test.rb

@@ -2,7 +2,18 @@
 
 class MessagesTest < ApplicationSystemTestCase
   setup do
-    @message = messages(:one)
+    @message1 = messages(:message1)
+    @message2 = messages(:message2)
+  end
+
+  test 'visiting ruby-dev index, and showing a message with an attachment' do
+    visit '/ruby-dev'
+    assert_content @message2.subject
+
+    click_link @message2.subject
+    assert_content @message2.body
+
+    click_link @message2.attachments_attachments.first.blob.filename.to_s
   end
 
   test "visiting the index" do