Store newly-uploaded files on save rather than assignment

1 files changed, 65 insertions, 0 deletions

diff --git a/activestorage/lib/active_storage/attached/changes/create_one.rb b/activestorage/lib/active_storage/attached/changes/create_one.rb
new file mode 100644
index 0000000000..bb59a651ba
--- /dev/null
+++ b/activestorage/lib/active_storage/attached/changes/create_one.rb
@@ -0,0 +1,65 @@
+# frozen_string_literal: true
+
+module ActiveStorage
+  class Attached::Changes::CreateOne #:nodoc:
+    attr_reader :name, :record, :attachable
+
+    def initialize(name, record, attachable)
+      @name, @record, @attachable = name, record, attachable
+    end
+
+    def attachment
+      @attachment ||= find_or_build_attachment
+    end
+
+    def blob
+      @blob ||= find_or_build_blob
+    end
+
+    def upload
+      case attachable
+      when ActionDispatch::Http::UploadedFile, Rack::Test::UploadedFile
+        blob.upload_without_unfurling(attachable.open)
+      when Hash
+        blob.upload_without_unfurling(attachable.fetch(:io))
+      end
+    end
+
+    def save
+      record.public_send("#{name}_attachment=", attachment)
+    end
+
+    private
+      def find_or_build_attachment
+        find_attachment || build_attachment
+      end
+
+      def find_attachment
+        if record.public_send("#{name}_blob") == blob
+          record.public_send("#{name}_attachment")
+        end
+      end
+
+      def build_attachment
+        ActiveStorage::Attachment.new(record: record, name: name, blob: blob)
+      end
+
+      def find_or_build_blob
+        case attachable
+        when ActiveStorage::Blob
+          attachable
+        when ActionDispatch::Http::UploadedFile, Rack::Test::UploadedFile
+          ActiveStorage::Blob.build_after_unfurling \
+            io: attachable.open,
+            filename: attachable.original_filename,
+            content_type: attachable.content_type
+        when Hash
+          ActiveStorage::Blob.build_after_unfurling(attachable)
+        when String
+          ActiveStorage::Blob.find_signed(attachable)
+        else
+          raise "Could not find or build blob: expected attachable, got #{attachable.inspect}"
+        end
+      end
+  end
+end