1 files changed, 24 insertions, 0 deletions
diff --git a/activestorage/app/models/active_storage/blob/identifiable.rb b/activestorage/app/models/active_storage/blob/identifiable.rb
new file mode 100644
index 0000000000..2c17ddc25f
--- /dev/null
+++ b/activestorage/app/models/active_storage/blob/identifiable.rb
@@ -0,0 +1,24 @@
+# frozen_string_literal: true
+
+module ActiveStorage::Blob::Identifiable
+  def identify
+    update! content_type: identify_content_type, identified: true unless identified?
+  end
+
+  def identified?
+    identified
+  end
+
+  private
+    def identify_content_type
+      Marcel::MimeType.for download_identifiable_chunk, name: filename.to_s, declared_type: content_type
+    end
+
+    def download_identifiable_chunk
+      if byte_size.positive?
+        service.download_chunk key, 0...4.kilobytes
+      else
+        ""
+      end
+    end
+end