From 5859e0fd3fff37a0b2d54f0cbf2eb24e6754e784 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ozan=20Arma=C4=9Fan?=
 <70442658+ozanarmagan@users.noreply.github.com>
Date: Thu, 6 Jun 2024 14:19:12 +0300
Subject: [PATCH] Fix filtering on stemmed fields (#1776)

* Fix filtering on stemmed fields

* Fix getting stemmer twice
---
 src/filter.cpp                     | 14 +++++++++++--
 test/collection_filtering_test.cpp | 32 ++++++++++++++++++++++++++++++
 2 files changed, 44 insertions(+), 2 deletions(-)

diff --git a/src/filter.cpp b/src/filter.cpp
index cba4e83d..7d55ef91 100644
--- a/src/filter.cpp
+++ b/src/filter.cpp
@@ -639,10 +639,20 @@ Option<bool> toFilter(const std::string expression,
                 return Option<bool>(400, "Error with filter field `" + _field.name +
                                          "`: Filter value array cannot be empty.");
             }
-
+            if(_field.stem) {
+                auto stemmer = _field.get_stemmer();
+                for (std::string& filter_value: filter_values) {
+                    filter_value = stemmer->stem(filter_value);
+                }
+            }
             filter_exp = {field_name, filter_values, {str_comparator}};
         } else {
-            filter_exp = {field_name, {raw_value.substr(filter_value_index)}, {str_comparator}};
+            std::string filter_value = raw_value.substr(filter_value_index);
+            if(_field.stem) {
+                auto stemmer = _field.get_stemmer();
+                filter_value = stemmer->stem(filter_value);
+            }
+            filter_exp = {field_name, {filter_value}, {str_comparator}};
         }
 
         filter_exp.apply_not_equals = apply_not_equals;
diff --git a/test/collection_filtering_test.cpp b/test/collection_filtering_test.cpp
index 95799dbf..56953d84 100644
--- a/test/collection_filtering_test.cpp
+++ b/test/collection_filtering_test.cpp
@@ -2564,3 +2564,35 @@ TEST_F(CollectionFilteringTest, PrefixFilterOnTextFields) {
         ASSERT_EQ(id, result_id);
     }
 }
+
+TEST_F(CollectionFilteringTest, FilterOnStemmedField) {
+    nlohmann::json schema = R"({
+         "name": "companies",
+         "fields": [
+           {"name": "keywords", "type": "string[]", "facet": true, "stem": true }
+         ]
+       })"_json;
+
+    auto op = collectionManager.create_collection(schema);
+    ASSERT_TRUE(op.ok());
+
+    auto coll = op.get();
+
+    nlohmann::json doc1 = {
+        {"id", "124"},
+        {"keywords", {"Restaurant"}}
+    };
+
+    nlohmann::json doc2 = {
+        {"id", "125"},
+        {"keywords", {"Baking"}}
+    };
+
+    ASSERT_TRUE(coll->add(doc1.dump()).ok());
+    ASSERT_TRUE(coll->add(doc2.dump()).ok());
+
+    auto results = coll->search("*", {}, "keywords:=Baking", {}, {}, {0}, 10, 1, FREQUENCY, {false}).get();
+    ASSERT_EQ(1, results["hits"].size());
+    ASSERT_EQ("125", results["hits"][0]["document"]["id"].get<std::string>());
+
+}
\ No newline at end of file