diff --git a/.gitignore b/.gitignore
index e3452839..5aa71532 100644
--- a/.gitignore
+++ b/.gitignore
@@ -13,3 +13,4 @@ Makefile.local
 merged_api.yaml
 tests/results
 Makefile.local
+log_build.txt
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 35913f8e..b3ee9a40 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -23,6 +23,7 @@ add_library(${PROJECT_NAME}_objs OBJECT
 )
 target_include_directories(${PROJECT_NAME}_objs PUBLIC ${CMAKE_CURRENT_SOURCE_DIR}/src)
 target_link_libraries(${PROJECT_NAME}_objs PUBLIC userver-core userver-postgresql)
+# target_compile_options(${PROJECT_NAME}_objs PRIVATE -Wfatal-errors)
 
 
 # The Service
diff --git a/Makefile b/Makefile
index 3d2a7f3f..fa74fe33 100644
--- a/Makefile
+++ b/Makefile
@@ -200,6 +200,10 @@ gen:
 	$(MAKE) gen-sources
 	$(MAKE) gen-all-headers
 
+.PHONY: build-log
+build-log:
+	$(MAKE) -s test-debug > log_build.txt 2>&1
+
 # # Internal hidden targets that are used only in docker environment
 # --in-docker-start-debug --in-docker-start-release: --in-docker-start-%: install-%
 # 	@sed -i 's/config_vars.yaml/config_vars.docker.yaml/g' /home/user/.local/etc/timetable_vsu_backend/static_config.yaml
diff --git a/src/openapi/base/traits/array.hpp b/src/openapi/base/traits/array.hpp
index 768ade49..7e5ad782 100644
--- a/src/openapi/base/traits/array.hpp
+++ b/src/openapi/base/traits/array.hpp
@@ -13,8 +13,7 @@ concept HasMin = requires
 {
     {
         T::kMin
-    }
-    ->std::convertible_to<utils::ConstexprOptional<std::int64_t>>;
+    };
 };
 
 template <typename T>
@@ -22,8 +21,7 @@ concept HasMax = requires
 {
     {
         T::kMax
-    }
-    ->std::convertible_to<utils::ConstexprOptional<std::int64_t>>;
+    };
 };
 
 template <typename T>
@@ -31,75 +29,37 @@ concept HasUniqueItems = requires
 {
     {
         T::kUniqueItems
-    }
-    ->std::convertible_to<utils::ConstexprOptional<bool>>;
+    };
 };
 
-template <typename T>
-concept HasNotMin = !HasMin<T>;
-
-template <typename T>
-concept HasNotMax = !HasMax<T>;
-
-template <typename T>
-concept HasNotUniqueItems = !HasUniqueItems<T>;
 }  // namespace checks
 
-namespace detail
-{
-template <checks::HasMin T>
-constexpr auto _getMin()
-{
-    return T::kMin;
-}
-
-template <checks::HasNotMin T>
-constexpr auto _getMin()
-{
-    return utils::ConstexprOptional<std::int64_t>{utils::kNull};
-}
-
-template <checks::HasMax T>
-constexpr auto _getMax()
-{
-    return T::kMax;
-}
-
-template <checks::HasNotMax T>
-constexpr auto _getMax()
-{
-    return utils::ConstexprOptional<std::int64_t>{utils::kNull};
-}
-
-template <checks::HasUniqueItems T>
-constexpr auto _getUniqueItems()
-{
-    return T::kUniqueItems;
-}
-
-template <checks::HasNotUniqueItems T>
-constexpr auto _getUniqueItems()
-{
-    return utils::ConstexprOptional<bool>{utils::kNull};
-}
-}  // namespace detail
 
 namespace traits
 {
 template <typename T>
 constexpr utils::ConstexprOptional<std::int64_t> GetMin()
 {
-    return detail::_getMin<T>();
+    if constexpr (checks::HasMin<T>){
+        return T::kMin;
+    }
+    else return utils::kNull;
 }
 template <typename T>
 constexpr utils::ConstexprOptional<std::int64_t> GetMax()
 {
-    return detail::_getMax<T>();
+    if constexpr (checks::HasMax<T>){
+      return T::kMax;
+    }
+    else return utils::kNull;
 }
 template <typename T>
 constexpr utils::ConstexprOptional<bool> GetUniqueItems()
 {
-    return detail::_getUniqueItems<T>();
+    if constexpr (checks::HasUniqueItems<T>){
+        return T::kUniqueItems;
+    }
+    else return utils::kNull;
 }
 
 template <typename Traits>
diff --git a/src/openapi/base/traits/optional.hpp b/src/openapi/base/traits/optional.hpp
index 99cfa9b2..990fd5db 100644
--- a/src/openapi/base/traits/optional.hpp
+++ b/src/openapi/base/traits/optional.hpp
@@ -12,36 +12,20 @@ concept HasUseNullOnFail = requires
 {
     {
         T::kUseNullOnFail
-    }
-    ->std::convertible_to<utils::ConstexprOptional<bool>>;
+    };
 };
 
 }  // namespace checks
 
-namespace detail
-{
-template <typename T>
-requires checks::HasUseNullOnFail<T> constexpr utils::ConstexprOptional<bool>
-_getUseNullOnFail()
-{
-    return T::kUseNullOnFail;
-}
-
-template <typename T>
-requires(!checks::HasUseNullOnFail<T>) constexpr utils::ConstexprOptional<
-    bool> _getUseNullOnFail()
-{
-    return utils::kNull;
-}
-
-}  // namespace detail
-
 namespace traits
 {
 template <typename T>
 constexpr utils::ConstexprOptional<bool> GetUseNullOnFail()
 {
-    return detail::_getUseNullOnFail<T>();
+    if constexpr (checks::HasUseNullOnFail<T>){
+        return T::kUseNullOnFail;
+    }
+    else return utils::kNull;
 }
 
 template <typename Traits>
diff --git a/src/openapi/base/traits/string.hpp b/src/openapi/base/traits/string.hpp
index b715d747..464d214a 100644
--- a/src/openapi/base/traits/string.hpp
+++ b/src/openapi/base/traits/string.hpp
@@ -12,42 +12,21 @@ namespace checks
 template <typename T>
 concept HasPattern = requires
 {
-    {
-        decltype(T::kPattern)::kSize
-    }
-    ->std::convertible_to<std::size_t>;
-    requires std::is_same_v<
-        utils::ConstexprString<decltype(T::kPattern)::kSize>,
-        std::remove_cv_t<decltype(T::kPattern)>>;
     {
         T::kPattern
-    }
-    ->std::convertible_to<utils::ConstexprString<decltype(T::kPattern)::kSize>>;
+    };
 };
 }  // namespace checks
 
-namespace detail
-{
-template <typename T>
-requires checks::HasPattern<T> constexpr auto _getPattern()
-{
-    return T::kPattern;
-}
-
-template <typename T>
-requires(!checks::HasPattern<T>) constexpr auto _getPattern()
-{
-    using Type = utils::ConstexprString<1>;
-    return Type{""};
-}
-}  // namespace detail
-
 namespace traits
 {
 template <typename T>
 constexpr auto GetPattern()
 {
-    return detail::_getPattern<T>();
+    if constexpr (checks::HasPattern<T>){
+        return T::kPattern;
+    }
+    else return utils::kEmptyString;
 }
 
 template <typename Traits>
diff --git a/src/utils/constexpr_optional.hpp b/src/utils/constexpr_optional.hpp
index f3f7a5e3..02c360ad 100644
--- a/src/utils/constexpr_optional.hpp
+++ b/src/utils/constexpr_optional.hpp
@@ -29,6 +29,10 @@ struct ConstexprOptional
     using value_type = T;
     T value_;
     bool has_value_;
+    constexpr ConstexprOptional() noexcept
+        : value_(T{}), has_value_(false)
+    {
+    }
     constexpr ConstexprOptional(const T& value) noexcept
         : value_(value), has_value_(true)
     {
diff --git a/src/utils/constexpr_string.hpp b/src/utils/constexpr_string.hpp
index d102d617..18627026 100644
--- a/src/utils/constexpr_string.hpp
+++ b/src/utils/constexpr_string.hpp
@@ -69,6 +69,9 @@ struct ConstexprString
         return string == lhs;
     }
 };
+
+constexpr ConstexprString<1> kEmptyString{};
+
 template <std::size_t n>
 ConstexprString(char const (&)[n]) -> ConstexprString<n>;
 
diff --git a/utests/openapi/json/parse/datetime.cpp b/utests/openapi/json/parse/datetime.cpp
index f26d9992..422a0689 100644
--- a/utests/openapi/json/parse/datetime.cpp
+++ b/utests/openapi/json/parse/datetime.cpp
@@ -12,7 +12,7 @@
 
 using namespace openapi;
 
-UTEST(Openapi_Json_Parse, BasicUuid)
+UTEST(Openapi_Json_Parse, BasicDatetime)
 {
     //2011-08-12T20:17:46.384Z