fix: SyntaxWarning: invalid escape sequence '\:'

invenio_app_rdm/records_ui/views/filters.py

@@ -3,6 +3,7 @@
 # Copyright (C) 2019-2024 CERN.
 # Copyright (C) 2019-2020 Northwestern University.
 # Copyright (C)      2021 TU Wien.
+# Copyright (C) 2024 Graz University of Technology.
 #
 # Invenio App RDM is free software; you can redistribute it and/or modify it
 # under the terms of the MIT License; see LICENSE file for more details.
@@ -183,9 +184,13 @@ def custom_fields_search(field, field_value, field_cfg=None):
         if not locale:
             locale = current_app.config.get("BABEL_DEFAULT_LOCALE", "en")
         # example: cern:experiments.title.en
-        namespace_string = "\:".join(namespace_array) + f".{localised_title}.{locale}"
+        # the \ is necessary for the lucene syntax but produces a SyntaxWarning.
+        # The r marks the string as raw and prevents the warning
+        # https://docs.python.org/3/reference/lexical_analysis.html#escape-sequences
+        namespace_string = r"\:".join(namespace_array) + f".{localised_title}.{locale}"
     else:
-        namespace_string = "\:".join(namespace_array)
+        namespace_string = r"\:".join(namespace_array)
+
     return url_for(
         "invenio_search_ui.search", q=f"custom_fields.{namespace_string}:{field_value}"
     )