Fix zero-byte files upload

3 files changed, 12 insertions, 1 deletions

diff --git a/activestorage/app/models/active_storage/blob/identifiable.rb b/activestorage/app/models/active_storage/blob/identifiable.rb
index 049e45dc3e..2c17ddc25f 100644
--- a/activestorage/app/models/active_storage/blob/identifiable.rb
+++ b/activestorage/app/models/active_storage/blob/identifiable.rb
@@ -15,6 +15,10 @@ module ActiveStorage::Blob::Identifiable
     end
 
     def download_identifiable_chunk
-      service.download_chunk key, 0...4.kilobytes
+      if byte_size.positive?
+        service.download_chunk key, 0...4.kilobytes
+      else
+        ""
+      end
     end
 end
diff --git a/activestorage/test/fixtures/files/empty_file.txt b/activestorage/test/fixtures/files/empty_file.txt
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/activestorage/test/fixtures/files/empty_file.txt
diff --git a/activestorage/test/service/s3_service_test.rb b/activestorage/test/service/s3_service_test.rb
index 4bfcda017f..559aa028f2 100644
--- a/activestorage/test/service/s3_service_test.rb
+++ b/activestorage/test/service/s3_service_test.rb
@@ -31,6 +31,13 @@ if SERVICE_CONFIGURATIONS[:s3]
       end
     end
 
+    test "upload a zero byte file" do
+      blob = directly_upload_file_blob filename: "empty_file.txt", content_type: nil
+      user = User.create! name: "DHH", avatar: blob
+
+      assert_equal user.avatar.blob, blob
+    end
+
     test "signed URL generation" do
       url = @service.url(@key, expires_in: 5.minutes,
         disposition: :inline, filename: ActiveStorage::Filename.new("avatar.png"), content_type: "image/png")