From f9bd8b6a6bbc91c8436602d56f376998da6ec8dc Mon Sep 17 00:00:00 2001
From: Sarah Hoffmann <lonvia@denofr.de>
Date: Mon, 8 Jun 2026 11:24:13 +0200
Subject: [PATCH] make sure 'replacements' exists and is of right type

---
 .../query_preprocessing/config.py             | 23 +++++++++++++++++--
 .../query_preprocessing/regex_replace.py      |  2 +-
 .../query_processing/test_regex_replace.py    | 15 ++++++++++--
 3 files changed, 35 insertions(+), 5 deletions(-)

diff --git a/src/nominatim_api/query_preprocessing/config.py b/src/nominatim_api/query_preprocessing/config.py
index a3c6a9ad..ab757c36 100644
--- a/src/nominatim_api/query_preprocessing/config.py
+++ b/src/nominatim_api/query_preprocessing/config.py
@@ -5,11 +5,15 @@
 # Copyright (C) 2026 by the Nominatim developer community.
 # For a full list of authors see the git log.
 """
-Configuration for Sanitizers.
+Configuration for query preprocessors.
 """
-from typing import Any
+from typing import Any, TypeVar
 from collections import UserDict
 
+from ..errors import UsageError
+
+T = TypeVar('T')
+
 
 class QueryConfig(UserDict[str, Any]):
     """ The `QueryConfig` class is a read-only dictionary
@@ -18,3 +22,18 @@ class QueryConfig(UserDict[str, Any]):
         accessors to standard preprocessor options that are used by many of the
         preprocessors.
     """
+
+    def require_typed(self, param: str, dtype: type[T]) -> T:
+        """ Return the value for the given parameter.
+            Raises a UsageError if the parameter is not present or
+            of the wrong type.
+        """
+        result = self.get(param)
+
+        if result is None:
+            raise UsageError(f"Parameter '{param}' missing.")
+
+        if not isinstance(result, dtype):
+            raise UsageError(f"Parameter '{param}' must be of type {dtype.__name__}")
+
+        return result
diff --git a/src/nominatim_api/query_preprocessing/regex_replace.py b/src/nominatim_api/query_preprocessing/regex_replace.py
index d62b1e18..2433c917 100644
--- a/src/nominatim_api/query_preprocessing/regex_replace.py
+++ b/src/nominatim_api/query_preprocessing/regex_replace.py
@@ -29,7 +29,7 @@ class _GenericPreprocessing:
         """Initialise the _GenericPreprocessing class with patterns from the ICU config file."""
         self.config = config
 
-        match_patterns = self.config.get('replacements', 'Key not found')
+        match_patterns = self.config.require_typed('replacements', list)
         self.compiled_patterns = [
             (re.compile(item['pattern']), item['replace']) for item in match_patterns
             ]
diff --git a/test/python/api/query_processing/test_regex_replace.py b/test/python/api/query_processing/test_regex_replace.py
index cb3f6037..26d32eb6 100644
--- a/test/python/api/query_processing/test_regex_replace.py
+++ b/test/python/api/query_processing/test_regex_replace.py
@@ -4,14 +4,15 @@
 #
 # Copyright (C) 2026 by the Nominatim developer community.
 # For a full list of authors see the git log.
-'''
+"""
 Tests for replacing values in an input using custom regex.
-'''
+"""
 import pytest
 
 import nominatim_api.search.query as qmod
 from nominatim_api.query_preprocessing.config import QueryConfig
 from nominatim_api.query_preprocessing import regex_replace
+from nominatim_api.errors import UsageError
 
 
 def run_preprocessor_on(query):
@@ -46,3 +47,13 @@ def test_split_phrases(inp, outp):
 
     out = run_preprocessor_on(query)
     assert out == [qmod.Phrase(qmod.PHRASE_ANY, text) for text in outp]
+
+
+def test_missing_replacement_section():
+    with pytest.raises(UsageError, match="'replacements' missing"):
+        regex_replace.create(QueryConfig())
+
+
+def test_bad_type_for_replacement():
+    with pytest.raises(UsageError, match="'replacements' must be of type list"):
+        regex_replace.create(QueryConfig({'replacements': 'something'}))
-- 
2.47.3