Add ActiveStorage::Blob#open

[David Robertson & George Claghorn]

1 files changed, 40 insertions, 0 deletions

diff --git a/activestorage/lib/active_storage/downloader.rb b/activestorage/lib/active_storage/downloader.rb
new file mode 100644
index 0000000000..7f5b4936a5
--- /dev/null
+++ b/activestorage/lib/active_storage/downloader.rb
@@ -0,0 +1,40 @@
+# frozen_string_literal: true
+
+module ActiveStorage
+  class Downloader
+    def initialize(blob)
+      @blob = blob
+    end
+
+    def download_blob_to_tempfile
+      open_tempfile do |file|
+        download_blob_to file
+        yield file
+      end
+    end
+
+    private
+      attr_reader :blob
+
+      def open_tempfile
+        file = Tempfile.open([ "ActiveStorage", tempfile_extension_with_delimiter ])
+
+        begin
+          yield file
+        ensure
+          file.close!
+        end
+      end
+
+      def download_blob_to(file)
+        file.binmode
+        blob.download { |chunk| file.write(chunk) }
+        file.flush
+        file.rewind
+      end
+
+      def tempfile_extension_with_delimiter
+        blob.filename.extension_with_delimiter
+      end
+  end
+end