From be74f60bf51cfaa0bc0fe5ad493e781e15d48d99 Mon Sep 17 00:00:00 2001
From: David Sobek <david.sobek@picknik.ai>
Date: Fri, 24 Apr 2026 08:13:49 -0600
Subject: [PATCH] Allow for vector to string conversions

---
 include/behaviortree_cpp/basic_types.h | 39 ++++++++++++++++++++++++--
 include/behaviortree_cpp/blackboard.h  | 11 --------
 tests/gtest_ports.cpp                  |  7 +++++
 3 files changed, 44 insertions(+), 13 deletions(-)

diff --git a/include/behaviortree_cpp/basic_types.h b/include/behaviortree_cpp/basic_types.h
index b61d49c16..5907d846f 100644
--- a/include/behaviortree_cpp/basic_types.h
+++ b/include/behaviortree_cpp/basic_types.h
@@ -3,6 +3,7 @@
 #include <chrono>
 #include <iostream>
 #include <functional>
+#include <sstream>
 #include <string_view>
 #include <typeinfo>
 #include <unordered_map>
@@ -246,6 +247,18 @@ constexpr bool IsConvertibleToString()
 
 Expected<std::string> toJsonString(const Any& value);
 
+// Helper trait to check if templated type is a std::vector
+template <typename T>
+struct is_vector : std::false_type
+{
+};
+
+template <typename T, typename A>
+struct is_vector<std::vector<T, A>> : std::true_type
+{
+  using ValueType = T;
+};
+
 /**
  * @brief toStr is the reverse operation of convertFromString.
  *
@@ -255,10 +268,33 @@ Expected<std::string> toJsonString(const Any& value);
 template <typename T>
 [[nodiscard]] std::string toStr(const T& value)
 {
+  auto throw_unspecialized_error = []() {
+    throw LogicError(StrCat("Function BT::toStr<T>() not specialized for type [",
+                            BT::demangle(typeid(T)), "]"));
+  };
+
   if constexpr(IsConvertibleToString<T>())
   {
     return static_cast<std::string>(value);
   }
+  else if constexpr(is_vector<T>::value)
+  {
+    try
+    {
+      using InnerType = typename is_vector<T>::ValueType;
+      std::stringstream ss;
+      for(auto it = value.begin(); it != --value.end(); ++it)
+      {
+        ss << toStr<InnerType>(*it) << ';';
+      }
+      ss << toStr<InnerType>(value.back());
+      return ss.str();
+    }
+    catch(LogicError&)
+    {
+      throw_unspecialized_error();
+    }
+  }
   else if constexpr(!std::is_arithmetic_v<T>)
   {
     if(auto str = toJsonString(Any(value)))
@@ -266,8 +302,7 @@ template <typename T>
       return *str;
     }
 
-    throw LogicError(StrCat("Function BT::toStr<T>() not specialized for type [",
-                            BT::demangle(typeid(T)), "]"));
+    throw_unspecialized_error();
   }
   else
   {
diff --git a/include/behaviortree_cpp/blackboard.h b/include/behaviortree_cpp/blackboard.h
index 409ef8a1a..436542bf0 100644
--- a/include/behaviortree_cpp/blackboard.h
+++ b/include/behaviortree_cpp/blackboard.h
@@ -26,17 +26,6 @@ struct StampedValue
   Timestamp stamp;
 };
 
-// Helper trait to check if templated type is a std::vector
-template <typename T>
-struct is_vector : std::false_type
-{
-};
-
-template <typename T, typename A>
-struct is_vector<std::vector<T, A>> : std::true_type
-{
-};
-
 // Helper function to check if a demangled type string is a std::vector<..>
 inline bool isVector(const std::string& type_name)
 {
diff --git a/tests/gtest_ports.cpp b/tests/gtest_ports.cpp
index eaaf9733a..cbe644aaf 100644
--- a/tests/gtest_ports.cpp
+++ b/tests/gtest_ports.cpp
@@ -6,6 +6,13 @@
 
 using namespace BT;
 
+TEST(toStr, ConvertsVectors)
+{
+  std::string val_str;
+  ASSERT_NO_THROW(val_str = BT::toStr(std::vector<int>{ 1, 2, 3, 4 }));
+  EXPECT_EQ(val_str, "1;2;3;4");
+}
+
 class NodeWithPorts : public SyncActionNode
 {
 public: