diff --git a/search/search_quality/helpers.cpp b/search/search_quality/helpers.cpp
index f030c5c04f..433bf4fb1c 100644
--- a/search/search_quality/helpers.cpp
+++ b/search/search_quality/helpers.cpp
@@ -30,7 +30,7 @@ void ChangeMaxNumberOfOpenFiles(size_t n)
 
 namespace m2
 {
-void FromJSONObject(json_t * root, string const & field, RectD & rect)
+void FromJSONObject(json_t * root, char const * field, RectD & rect)
 {
   json_t * r = base::GetJSONObligatoryField(root, field);
   double minX, minY, maxX, maxY;
@@ -44,23 +44,38 @@ void FromJSONObject(json_t * root, string const & field, RectD & rect)
   rect.setMaxY(maxY);
 }
 
-void ToJSONObject(json_t & root, string const & field, RectD const & rect)
+void ToJSONObject(json_t & root, char const * field, RectD const & rect)
 {
   auto json = base::NewJSONObject();
   ToJSONObject(*json, "minx", rect.minX());
   ToJSONObject(*json, "miny", rect.minY());
   ToJSONObject(*json, "maxx", rect.maxX());
   ToJSONObject(*json, "maxy", rect.maxY());
-  json_object_set_new(&root, field.c_str(), json.release());
+  json_object_set_new(&root, field, json.release());
 }
 
-void FromJSONObject(json_t * root, string const & field, PointD & point)
+void FromJSONObject(json_t * root, string const & field, RectD & rect)
+{
+  FromJSONObject(root, field.c_str(), rect);
+}
+
+void ToJSONObject(json_t & root, string const & field, RectD const & rect)
+{
+  ToJSONObject(root, field.c_str(), rect);
+}
+
+void FromJSONObject(json_t * root, char const * field, PointD & point)
 {
   json_t * p = base::GetJSONObligatoryField(root, field);
   ParsePoint(p, point);
 }
 
-bool FromJSONObjectOptional(json_t * root, std::string const & field, PointD & point)
+void FromJSONObject(json_t * root, string const & field, PointD & point)
+{
+  FromJSONObject(root, field.c_str(), point);
+}
+
+bool FromJSONObjectOptional(json_t * root, char const * field, PointD & point)
 {
   json_t * p = base::GetJSONOptionalField(root, field);
   if (!p || base::JSONIsNull(p))
@@ -70,11 +85,21 @@ bool FromJSONObjectOptional(json_t * root, std::string const & field, PointD & p
   return true;
 }
 
-void ToJSONObject(json_t & root, string const & field, PointD const & point)
+void ToJSONObject(json_t & root, char const * field, PointD const & point)
 {
   auto json = base::NewJSONObject();
   ToJSONObject(*json, "x", point.x);
   ToJSONObject(*json, "y", point.y);
-  json_object_set_new(&root, field.c_str(), json.release());
+  json_object_set_new(&root, field, json.release());
+}
+
+bool FromJSONObjectOptional(json_t * root, std::string const & field, PointD & point)
+{
+  return FromJSONObjectOptional(root, field.c_str(), point);
+}
+
+void ToJSONObject(json_t & root, string const & field, PointD const & point)
+{
+  ToJSONObject(root, field.c_str(), point);
 }
 }  // namespace m2
diff --git a/search/search_quality/helpers.hpp b/search/search_quality/helpers.hpp
index 1829c4b78c..6ea9eb9e76 100644
--- a/search/search_quality/helpers.hpp
+++ b/search/search_quality/helpers.hpp
@@ -17,11 +17,16 @@ void ChangeMaxNumberOfOpenFiles(size_t n);
 
 namespace m2
 {
+void FromJSONObject(json_t * root, char const * field, RectD & rect);
+void ToJSONObject(json_t & root, char const * field, RectD const & rect);
 void FromJSONObject(json_t * root, std::string const & field, RectD & rect);
 void ToJSONObject(json_t & root, std::string const & field, RectD const & rect);
 
+void FromJSONObject(json_t * root, char const * field, PointD & point);
+bool FromJSONObjectOptional(json_t * root, char const * field, PointD & point);
 void FromJSONObject(json_t * root, std::string const & field, PointD & point);
 bool FromJSONObjectOptional(json_t * root, std::string const & field, PointD & point);
 
+void ToJSONObject(json_t & root, char const * field, PointD const & point);
 void ToJSONObject(json_t & root, std::string const & field, PointD const & point);
 }  // namespace m2
diff --git a/search/search_quality/sample.cpp b/search/search_quality/sample.cpp
index 693ed8f44b..2f8ace2f91 100644
--- a/search/search_quality/sample.cpp
+++ b/search/search_quality/sample.cpp
@@ -200,7 +200,7 @@ void Sample::FillSearchParams(search::SearchParams & params) const
   params.m_needHighlighting = false;
 }
 
-void FromJSONObject(json_t * root, string const & field, Sample::Result::Relevance & relevance)
+void FromJSONObject(json_t * root, char const * field, Sample::Result::Relevance & relevance)
 {
   string r;
   FromJSONObject(root, field, r);
@@ -214,7 +214,7 @@ void FromJSONObject(json_t * root, string const & field, Sample::Result::Relevan
     CHECK(false, ("Unknown relevance:", r));
 }
 
-void ToJSONObject(json_t & root, string const & field, Sample::Result::Relevance relevance)
+void ToJSONObject(json_t & root, char const * field, Sample::Result::Relevance relevance)
 {
   using Relevance = Sample::Result::Relevance;
 
@@ -226,7 +226,17 @@ void ToJSONObject(json_t & root, string const & field, Sample::Result::Relevance
   case Relevance::Irrelevant: r = "irrelevant"; break;
   }
 
-  json_object_set_new(&root, field.c_str(), json_string(r.c_str()));
+  json_object_set_new(&root, field, json_string(r.c_str()));
+}
+
+void FromJSONObject(json_t * root, string const & field, Sample::Result::Relevance & relevance)
+{
+  FromJSONObject(root, field.c_str(), relevance);
+}
+
+void ToJSONObject(json_t & root, string const & field, Sample::Result::Relevance relevance)
+{
+  ToJSONObject(root, field.c_str(), relevance);
 }
 
 void FromJSON(json_t * root, Sample::Result & result)
diff --git a/search/search_quality/sample.hpp b/search/search_quality/sample.hpp
index d63ed37d89..757877c64a 100644
--- a/search/search_quality/sample.hpp
+++ b/search/search_quality/sample.hpp
@@ -65,6 +65,9 @@ struct Sample
   std::vector<strings::UniString> m_relatedQueries;
 };
 
+void FromJSONObject(json_t * root, char const * field,
+                    Sample::Result::Relevance & relevance);
+void ToJSONObject(json_t & root, char const * field, Sample::Result::Relevance relevance);
 void FromJSONObject(json_t * root, std::string const & field,
                     Sample::Result::Relevance & relevance);
 void ToJSONObject(json_t & root, std::string const & field, Sample::Result::Relevance relevance);