fix: linefeeds in custom_query (#3813)

* fix linefeeds in custom_query

* add double quote test case

Author: tstadel

haystack/document_stores/search_engine.py

@@ -1064,7 +1064,7 @@ def _construct_query_body(
         elif custom_query:  # substitute placeholder for query and filters for the custom_query template string
             template = Template(custom_query)
             # replace all "${query}" placeholder(s) with query
-            substitutions = {"query": f'"{query}"'}
+            substitutions = {"query": json.dumps(query)}
             # For each filter we got passed, we'll try to find & replace the corresponding placeholder in the template
             # Example: filters={"years":[2018]} => replaces {$years} in custom_query with '[2018]'
             if filters:

test/nodes/test_retriever.py

@@ -272,6 +272,14 @@ def test_elasticsearch_custom_query():
     results = retriever.retrieve(query="test", filters={"years": ["2020", "2021"]})
     assert len(results) == 4
 
+    # test linefeeds in query
+    results = retriever.retrieve(query="test\n", filters={"years": ["2020", "2021"]})
+    assert len(results) == 3
+
+    # test double quote in query
+    results = retriever.retrieve(query='test"', filters={"years": ["2020", "2021"]})
+    assert len(results) == 3
+
     # test custom "term" query
     retriever = BM25Retriever(
         document_store=document_store,