Extract ActiveStorage::Streaming so your own controllers can use it (rails#41440)

Extract ActiveStorage::Streaming so your own controller can use it

Author: David Heinemeier Hansson

.rubocop.yml

@@ -89,9 +89,6 @@ Layout/EmptyLinesAroundModuleBody:
 Style/HashSyntax:
   Enabled: true
 
-Layout/FirstArgumentIndentation:
-  Enabled: true
-
 # Method definitions after `private` or `protected` isolated calls need one
 # extra level of indentation.
 Layout/IndentationConsistency:

activestorage/CHANGELOG.md

@@ -1,3 +1,20 @@
+*   Add `ActiveStorage::Streaming` module that can be included in a controller to get access to `#send_blob_stream`,
+    which wraps the new `ActionController::Base#send_stream` method to stream a blob from cloud storage:
+    
+    ```ruby
+    class MyPublicBlobsController < ApplicationController
+      include ActiveStorage::SetBlob, ActiveStorage::Streaming
+      
+      def show
+        http_cache_forever(public: true) do
+          send_blob_stream @blob, disposition: params[:disposition]
+        end
+      end
+    end
+    ```
+    
+    *DHH*
+
 *   Add ability to use pre-defined variants.
 
     ```ruby

activestorage/app/controllers/active_storage/base_controller.rb

@@ -2,18 +2,9 @@
 
 # The base class for all Active Storage controllers.
 class ActiveStorage::BaseController < ActionController::Base
-  include ActiveStorage::SetCurrent
+  include ActiveStorage::SetCurrent, ActiveStorage::Streaming
 
   protect_from_forgery with: :exception
 
   self.etag_with_template_digest = false
-
-  private
-    def stream(blob)
-      blob.download do |chunk|
-        response.stream.write chunk
-      end
-    ensure
-      response.stream.close
-    end
 end

activestorage/app/controllers/active_storage/blobs/proxy_controller.rb

@@ -3,12 +3,10 @@
 # Proxy files through application. This avoids having a redirect and makes files easier to cache.
 class ActiveStorage::Blobs::ProxyController < ActiveStorage::BaseController
   include ActiveStorage::SetBlob
-  include ActiveStorage::SetHeaders
 
   def show
     http_cache_forever public: true do
-      set_content_headers_from @blob
-      stream @blob
+      send_blob_stream @blob
     end
   end
 end

activestorage/app/controllers/active_storage/representations/proxy_controller.rb

@@ -3,12 +3,10 @@
 # Proxy files through application. This avoids having a redirect and makes files easier to cache.
 class ActiveStorage::Representations::ProxyController < ActiveStorage::BaseController
   include ActiveStorage::SetBlob
-  include ActiveStorage::SetHeaders
 
   def show
     http_cache_forever public: true do
-      set_content_headers_from representation.image
-      stream representation
+      send_blob_stream representation.image
     end
   end
 

activestorage/app/controllers/concerns/active_storage/set_headers.rb

@@ -0,0 +1,21 @@
+# frozen_string_literal: true
+
+module ActiveStorage::Streaming
+  DEFAULT_BLOB_STREAMING_DISPOSITION = "inline"
+
+  include ActionController::Live
+
+  private
+    # Stream the blob from storage directly to the response. The disposition can be controlled by setting +disposition+.
+    # The content type and filename is set directly from the +blob+.
+    def send_blob_stream(blob, disposition: nil) #:doc:
+      send_stream(
+          filename: blob.filename.sanitized,
+          disposition: blob.forced_disposition_for_serving || disposition || DEFAULT_BLOB_STREAMING_DISPOSITION,
+          type: blob.content_type_for_serving) do |stream|
+        blob.download do |chunk|
+          stream.write chunk
+        end
+      end
+    end
+end

activestorage/app/controllers/concerns/active_storage/streaming.rb

@@ -48,7 +48,7 @@ class ActiveStorage::Representations::ProxyControllerWithPreviewsTest < ActionDi
 
     assert_predicate @blob.preview_image, :attached?
 
-    image = read_image(@blob.preview_image.variant(resize: "100x100"))
+    image = read_image(@blob.preview_image.variant(resize: "100x100").processed)
     assert_equal 77, image.width
     assert_equal 100, image.height
   end