When looking for a key that does not exist we now raise a warning, (if there is a valid callback).

CHANGELOG.md

@@ -5,6 +5,14 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [0.2.5] - 2026-06-11
+
+### Added
+- Added warning callback trigger when attempting to retrieve non-existent keys in `TJValueObject` using `try_get_string`, `get_*(..)`, or `get<>(..)` methods.
+
+### Changed
+- Incremented version to 0.3.0.
+
 ## [0.2.4] - 2026-05-20
 
 ### Added

README.md

@@ -2,7 +2,7 @@
 
 [![CI](https://github.com/FFMG/TinyJSON/actions/workflows/c-cpp.yml/badge.svg)](https://github.com/FFMG/TinyJSON/actions/workflows/c-cpp.yml)
 [![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](LICENSE)
-[![Version](https://img.shields.io/badge/version-0.2.4-blue.svg)](src/TinyJSON.h)
+[![Version](https://img.shields.io/badge/version-0.2.5-blue.svg)](src/TinyJSON.h)
 
 A lightweight and lightning-fast C++ JSON & JSON5 parser designed for high performance and minimal footprint.
 
@@ -131,8 +131,8 @@ The version is set in the `TinyJSON.h` file.
 ```cpp
 static const short TJ_VERSION_MAJOR = 0;
 static const short TJ_VERSION_MINOR = 2;
-static const short TJ_VERSION_PATCH = 4;
-static const char TJ_VERSION_STRING[] = "0.2.4";
+static const short TJ_VERSION_PATCH = 5;
+static const char TJ_VERSION_STRING[] = "0.2.5";
 ```
 
 ### Simple Value Access
@@ -169,6 +169,7 @@ if (tj) {
   * json5_1_0_0
 * Callback: (`callback_function:std::function<void(message_type, const TJCHAR*)>`)  Callback function called where there is an error, warning etc.
   NB: The Callback function is called even if Throw is false.
+  * If a getter method (`try_get_string`, `get_*(..)`, or `get<>(..)`) is called on a key that does not exist in a `TJValueObject`, a warning message indicating the missing key (e.g. `"The key 'missing' was not found!"`) is passed to the callback function.
   * trace
   * debug
   * info
@@ -673,7 +674,7 @@ auto doubles = obj->get<std::vector<double>>("floats");
 #### Strict Get values
 
 
-Getter methods on `TJValue` (or through `TJValueObject` keys) can be used to retrieve specific types. By default, these methods are non-strict and return default values if the type is incorrect. By setting `strict: true` in `parse_options`, these methods will throw a `TJParseException` instead.
+Getter methods on `TJValue` (or through `TJValueObject` keys) can be used to retrieve specific types. By default, these methods are non-strict and return default values if the type is incorrect. By setting `strict: true` in `parse_options`, these methods will throw a `TJParseException` instead. If a key is not found when calling `try_get_string`, `get_*(..)`, or `get<>(..)`, a warning callback is triggered with a message indicating the key that was not found (e.g. `"The key 'missing' was not found!"`) if a callback function is registered in `parse_options`.
 
   - get_number<T>()
   - get_float<T>()

src/TinyJSON.cpp

@@ -5396,16 +5396,68 @@ namespace TinyJSON
     return object;
   }
 
+  void TJValueObject::raise_key_not_found(const TJCHAR* key, bool is_strict) const
+  {
+    if (key == nullptr)
+    {
+      return;
+    }
+    int key_len = 0;
+    while (key[key_len] != 0)
+    {
+      key_len++;
+    }
+    int total_len = 9 + key_len + 17;
+    TJCHAR* msg = new TJCHAR[total_len + 1];
+
+    const TJCHAR* prefix = TJCHARPREFIX("The key '");
+    for (int i = 0; i < 9; ++i)
+    {
+      msg[i] = prefix[i];
+    }
+
+    for (int i = 0; i < key_len; ++i)
+    {
+      msg[9 + i] = key[i];
+    }
+
+    const TJCHAR* suffix = TJCHARPREFIX("' was not found!");
+    for (int i = 0; i < 17; ++i)
+    {
+      msg[9 + key_len + i] = suffix[i];
+    }
+
+    msg[total_len] = 0;
+
+    if (is_strict)
+    {
+      _parse_options.callback_function(parse_options::message_type::fatal, msg);
+      if (_parse_options.throw_exception)
+      {
+#if TJ_USE_CHAR == 1
+        TJParseException ex(msg);
+        delete[] msg;
+        throw ex;
+#else
+        delete[] msg;
+        throw TJParseException("The key was not found!");
+#endif
+      }
+    }
+    else
+    {
+      _parse_options.callback_function(parse_options::message_type::warning, msg);
+    }
+
+    delete[] msg;
+  }
+
   Optional<long double> TJValueObject::get_raw_float(const TJCHAR* key, bool case_sensitive) const
   {
     auto value = try_get_value(key, case_sensitive);
     if (nullptr == value)
     {
-      if (_parse_options.strict)
-      {
-        ParseResult _parse_result(_parse_options);
-        _parse_result.assign_exception_message_and_throw("The key was not found!");
-      }
+      raise_key_not_found(key, _parse_options.strict);
       return Optional<long double>();
     }
     return Optional<long double>(value->get_raw_float());
@@ -5416,11 +5468,7 @@ namespace TinyJSON
     auto value = try_get_value(key, case_sensitive);
     if (nullptr == value)
     {
-      if (_parse_options.strict)
-      {
-        ParseResult _parse_result(_parse_options);
-        _parse_result.assign_exception_message_and_throw("The key was not found!");
-      }
+      raise_key_not_found(key, _parse_options.strict);
       return Optional<long long>();
     }
     return Optional<long long>(value->get_raw_number());
@@ -5431,11 +5479,7 @@ namespace TinyJSON
     auto value = try_get_value(key, case_sensitive);
     if (nullptr == value)
     {
-      if (_parse_options.strict)
-      {
-        ParseResult _parse_result(_parse_options);
-        _parse_result.assign_exception_message_and_throw("The key was not found!");
-      }
+      raise_key_not_found(key, _parse_options.strict);
       return Optional<std::vector<long double>>();
     }
     return Optional<std::vector<long double>>(value->get_raw_floats());
@@ -5446,11 +5490,7 @@ namespace TinyJSON
     auto value = try_get_value(key, case_sensitive);
     if (nullptr == value)
     {
-      if (_parse_options.strict)
-      {
-        ParseResult _parse_result(_parse_options);
-        _parse_result.assign_exception_message_and_throw("The key was not found!");
-      }
+      raise_key_not_found(key, _parse_options.strict);
       return Optional<std::vector<long long>>();
     }
     return Optional<std::vector<long long>>(value->get_raw_numbers());
@@ -5461,11 +5501,7 @@ namespace TinyJSON
     auto value = try_get_value(key, case_sensitive);
     if (nullptr == value)
     {
-      if (_parse_options.strict)
-      {
-        ParseResult _parse_result(_parse_options);
-        _parse_result.assign_exception_message_and_throw("The key was not found!");
-      }
+      raise_key_not_found(key, _parse_options.strict);
       return TJCHARPREFIX("");
     }
     return value->get_string();
@@ -5476,11 +5512,7 @@ namespace TinyJSON
     auto value = try_get_value(key, case_sensitive);
     if (nullptr == value)
     {
-      if (_parse_options.strict)
-      {
-        ParseResult _parse_result(_parse_options);
-        _parse_result.assign_exception_message_and_throw("The key was not found!");
-      }
+      raise_key_not_found(key, _parse_options.strict);
       return false;
     }
     return value->get_boolean();
@@ -5898,6 +5930,7 @@ namespace TinyJSON
     auto value = try_get_value(key, case_sensitive);
     if (nullptr == value)
     {
+      raise_key_not_found(key, false);
       return nullptr;
     }
 

src/TinyJSON.h

@@ -45,11 +45,12 @@
 // v0.2.1 - added remove_at to TJValueArray.
 // v0.2.2 - added support for Json5 https://github.com/json5/
 // v0.2.3 - added atomic file saving
-// v0.2.4 - added operator[] and as<T>() accessors to TJValue
+// v0.2.4 - added operator[] and as<T>() accessor to TJValue
+// v0.2.5 - added raise warning when key is not found.
 static const short TJ_VERSION_MAJOR = 0;
 static const short TJ_VERSION_MINOR = 2;
-static const short TJ_VERSION_PATCH = 4;
-static const char TJ_VERSION_STRING[] = "0.2.4";
+static const short TJ_VERSION_PATCH = 5;
+static const char TJ_VERSION_STRING[] = "0.2.5";
 
 #ifndef TJ_USE_CHAR
 #  define TJ_USE_CHAR 1
@@ -1157,6 +1158,7 @@ class TJDictionary;
     }
 
   private:
+    void raise_key_not_found(const TJCHAR* key, bool is_strict) const;
     template<typename V>
     std::vector<V> get_vector_internal(const TJCHAR* key, bool case_sensitive, std::true_type) const
     {

tests/CMakeLists.txt

@@ -35,6 +35,7 @@ set( Sources
   "testtinyjsonstrings.cpp"
   testtinyjsonvaluesget.cpp
   testtinyjsonversion.cpp
+  testtinyjsonwarnings.cpp
   testtinyjsonconstructors.cpp
   testtinyjsonwrite.cpp
   testtinyjsonset.cpp

tests/testtinyjsonexceptions.cpp

@@ -285,7 +285,7 @@ TEST(TestException, GettingNonExistentKeyWillLogAndNotThrow) {
   options.strict = true;
   options.callback_function = [&](TinyJSON::parse_options::message_type message_type, const TJCHAR* exception_message) {
     EXPECT_EQ(message_type, TinyJSON::parse_options::fatal);
-    EXPECT_STREQ(exception_message, "The key was not found!");
+    EXPECT_STREQ(exception_message, "The key 'b' was not found!");
     called = true;
     };
   TinyJSON::TJValue* json = TinyJSON::TJ::parse("{\"a\" : 12}", options);

tests/testtinyjsonversion.cpp

@@ -5,18 +5,22 @@
 #define TJ_USE_CHAR 1
 #include "../src/TinyJSON.h"
 
-TEST(TestVersion, CheckVersionMajor) {
+TEST(TestVersion, CheckVersionMajor)
+{
   ASSERT_EQ(0, TJ_VERSION_MAJOR);
 }
 
-TEST(TestVersion, CheckVersionMinor) {
+TEST(TestVersion, CheckVersionMinor)
+{
   ASSERT_EQ(2, TJ_VERSION_MINOR);
 }
 
-TEST(TestVersion, CheckVersionPatch) {
-  ASSERT_EQ(4, TJ_VERSION_PATCH);
+TEST(TestVersion, CheckVersionPatch)
+{
+  ASSERT_EQ(5, TJ_VERSION_PATCH);
 }
 
-TEST(TestVersion, CheckVersionString) {
-  ASSERT_STREQ("0.2.4", TJ_VERSION_STRING);
+TEST(TestVersion, CheckVersionString)
+{
+  ASSERT_STREQ("0.2.5", TJ_VERSION_STRING);
 }