update search page to show no resutl found message and tell how to search

src/ui/widgets/searchPage.py

@@ -143,6 +143,8 @@ class SearchStatisticPage(QtWidgets.QDialog, Ui_Dialog):
             self.stackedWidget_4.setCurrentIndex(1)
 
     def search_book(self):
+        self.no_result.setText("")
+
         self.book_search_result.setRowCount(0)
         signature = self.search_by_signature.text()
         title = self.search_by_title.text()
@@ -151,9 +153,11 @@ class SearchStatisticPage(QtWidgets.QDialog, Ui_Dialog):
             "title": title if title != "" else None,
         }
         params = {key: value for key, value in params.items() if value is not None}
-        log.debug(params)
+        log.info(params)
         retdata = self.db.searchBook(params)
-        if retdata is None:
+        log.info(retdata)
+        if retdata == [] or retdata is None:
+            self.no_result.setText("Keine Ergebnisse gefunden")
             return
         for book in retdata:
             log.debug(book)