update function for a attachmentFile

src/views/feature/Feature_detail.vue

@@ -458,10 +458,10 @@ export default {
       //console.log("POST comment", data);
     },
     getAttachmentFileData(evt) {
-      const input = evt.target.value;
-      const period = input.lastIndexOf(".");
-      const fileName = input.substring(0, period);
-      const fileExtension = input.substring(period + 1);
+      const files = evt.target.files || evt.dataTransfer.files;
+      const period = files[0].name.lastIndexOf(".");
+      const fileName = files[0].name.substring(0, period)
+      const fileExtension = files[0].name.substring(period + 1);
       const shortName = fileName.slice(0, 10) + "[...]." + fileExtension;
       this.comment_form.attachment_file.value = shortName;
       this.comment_form.title.value = shortName;