C++: Hello API & OpenAPI with Swagger (#28)

* C++ web app

* WIP: Get APIs working

* Add commented code to adjust swagger/openapi doc URLs

* Remove files that are no longer needed

* Add a POST: /ping route, and fix GET: /hello

* / redirects to /swagger/ui

Until oatpp/oatpp-swagger#99 is addressed

* Tag "Hello API" endpoints with "exp"

* Update Readme

Author: gldraphael

README.md

@@ -21,10 +21,10 @@ Service  | Port
 
 |                       | C++ | C# | Go | Python | Rust |
 |-----------------------|-----|----|----|--------|------|
-| Hello API             | ❌ | ✅ | ✅ |  ✅   |  ✅  |
-| Open API & Swagger UI | ❌ | ✅ | ✅ |  ✅   |  ✅  |
+| Hello API             | ✅ | ✅ | ✅ |  ✅   |  ✅  |
+| Open API & Swagger UI | ✅ | ✅ | ✅ |  ✅   |  ✅  |
 | Dev container         | ✅ | ✅ | ✅ |  ✅   |  ✅  |
-| Dependency management | ❌ | ✅ | ✅ |  ✅   |  ❌  |
+| Dependency management | ✅ | ✅ | ✅ |  ✅   |  ❌  |
 | Configuration         | ❌ | ✅ | ✅ |  ✅   |  ❌  |
 | Structured logging    | ❌ | ❌ | ❌ |  ❌   |  ❌  |
 | Docker container      | ❌ | ✅ | ✅ |  ✅   |  ❌  |

cpp/.gitignore

@@ -1 +1,4 @@
 bin/
+
+build/
+vcpkg_installed/

cpp/.vscode/c_cpp_properties.json

@@ -9,7 +9,8 @@
             "compilerPath": "/usr/bin/g++-14",
             "cStandard": "c17",
             "cppStandard": "c++23",
-            "intelliSenseMode": "gcc-x64"
+            "intelliSenseMode": "gcc-x64",
+            "configurationProvider": "ms-vscode.cmake-tools"
         }
     ],
     "version": 4

cpp/.vscode/launch.json

@@ -0,0 +1,47 @@
+cmake_minimum_required(VERSION 3.30)
+project(lpg VERSION 0.1.0 LANGUAGES CXX)
+set(CMAKE_CXX_STANDARD 23)
+
+
+add_library(lpg-lib
+
+        src/dto/MessageDto.hpp
+        src/dto/StatusDto.hpp
+
+        src/controller/StaticController.hpp
+        src/controller/HelloApiController.hpp
+
+        src/AppComponent.hpp
+        src/SwaggerComponent.hpp
+        src/ErrorHandler.cpp
+        src/ErrorHandler.hpp
+)
+
+
+find_package(oatpp          1.3.0 REQUIRED)
+find_package(oatpp-swagger  1.3.0 REQUIRED)
+
+target_link_libraries(lpg-lib
+        PUBLIC oatpp::oatpp
+        PUBLIC oatpp::oatpp-swagger
+)
+
+add_definitions(
+    ## define path to swagger-ui static resources folder
+    -DOATPP_SWAGGER_RES_PATH="${oatpp-swagger_INCLUDE_DIRS}/../bin/oatpp-swagger/res"
+)
+
+if(CMAKE_SYSTEM_NAME MATCHES Linux)
+    find_package(Threads REQUIRED)
+    target_link_libraries(lpg-lib INTERFACE Threads::Threads ${CMAKE_DL_LIBS})
+endif()
+
+
+# Add executable
+add_executable(lpg 
+    src/App.cpp
+)
+
+target_link_libraries(lpg 
+    lpg-lib
+)

cpp/.vscode/tasks.json

@@ -0,0 +1,19 @@
+{
+    "version": 8,
+    "configurePresets": [
+        {
+            "name": "main",
+            "displayName": "GCC 14.2.0 x86_64-linux-gnu",
+            "description": "Using compilers: C = /usr/bin/gcc, CXX = /usr/bin/g++",
+            "binaryDir": "${sourceDir}/out/build/${presetName}",
+            "cacheVariables": {
+                "CMAKE_INSTALL_PREFIX": "${sourceDir}/out/install/${presetName}",
+                "CMAKE_C_COMPILER": "/usr/bin/gcc",
+                "CMAKE_CXX_COMPILER": "/usr/bin/g++-14",
+                "CMAKE_BUILD_TYPE": "Debug",
+                "CMAKE_TOOLCHAIN_FILE": "$env{VCPKG_ROOT}/scripts/buildsystems/vcpkg.cmake",
+                "VCPKG_TARGET_TRIPLET": "x64-linux"
+            }
+        }
+    ]
+}

cpp/CMakeLists.txt

@@ -0,0 +1,62 @@
+
+#include "AppComponent.hpp"
+
+#include "controller/StaticController.hpp"
+#include "controller/HelloApiController.hpp"
+
+#include "oatpp-swagger/Controller.hpp"
+
+#include "oatpp/network/Server.hpp"
+
+#include <iostream>
+
+void run() {
+  
+  AppComponent components; // Create scope Environment components
+  
+  /* Get router component */
+  OATPP_COMPONENT(std::shared_ptr<oatpp::web::server::HttpRouter>, router);
+
+  oatpp::web::server::api::Endpoints docEndpoints;
+
+//   docEndpoints.append(router->addController(UserController::createShared())->getEndpoints());
+
+    docEndpoints.append(router ->addController(HelloApiController::createShared())->getEndpoints());
+  router->addController(oatpp::swagger::Controller::createShared(docEndpoints));
+  router->addController(StaticController::createShared());
+
+  /* Get connection handler component */
+  OATPP_COMPONENT(std::shared_ptr<oatpp::network::ConnectionHandler>, connectionHandler);
+
+  /* Get connection provider component */
+  OATPP_COMPONENT(std::shared_ptr<oatpp::network::ServerConnectionProvider>, connectionProvider);
+
+  /* create server */
+  oatpp::network::Server server(connectionProvider,
+                                connectionHandler);
+  
+  OATPP_LOGD("Server", "Running on port %s...", connectionProvider->getProperty("port").toString()->c_str());
+  
+  server.run();
+  
+}
+
+/**
+ *  main
+ */
+int main(int argc, const char * argv[]) {
+
+  oatpp::base::Environment::init();
+
+  run();
+  
+  /* Print how many objects were created during app running, and what have left-probably leaked */
+  /* Disable object counting for release builds using '-D OATPP_DISABLE_ENV_OBJECT_COUNTERS' flag for better performance */
+  std::cout << "\nEnvironment:\n";
+  std::cout << "objectsCount = " << oatpp::base::Environment::getObjectsCount() << "\n";
+  std::cout << "objectsCreated = " << oatpp::base::Environment::getObjectsCreated() << "\n\n";
+  
+  oatpp::base::Environment::destroy();
+  
+  return 0;
+}

cpp/CMakePresets.json

@@ -0,0 +1,68 @@
+
+#ifndef AppComponent_hpp
+#define AppComponent_hpp
+
+#include "SwaggerComponent.hpp"
+
+#include "ErrorHandler.hpp"
+
+#include "oatpp/web/server/HttpConnectionHandler.hpp"
+#include "oatpp/web/server/HttpRouter.hpp"
+#include "oatpp/network/tcp/server/ConnectionProvider.hpp"
+
+#include "oatpp/parser/json/mapping/ObjectMapper.hpp"
+
+#include "oatpp/core/macro/component.hpp"
+
+/**
+ *  Class which creates and holds Application components and registers components in oatpp::base::Environment
+ *  Order of components initialization is from top to bottom
+ */
+class AppComponent {
+public:
+  
+  /**
+   *  Swagger component
+   */
+  SwaggerComponent swaggerComponent;
+
+  /**
+   * Create ObjectMapper component to serialize/deserialize DTOs in Controller's API
+   */
+  OATPP_CREATE_COMPONENT(std::shared_ptr<oatpp::data::mapping::ObjectMapper>, apiObjectMapper)([] {
+    auto objectMapper = oatpp::parser::json::mapping::ObjectMapper::createShared();
+    objectMapper->getDeserializer()->getConfig()->allowUnknownFields = false;
+    return objectMapper;
+  }());
+  
+  /**
+   *  Create ConnectionProvider component which listens on the port
+   */
+  OATPP_CREATE_COMPONENT(std::shared_ptr<oatpp::network::ServerConnectionProvider>, serverConnectionProvider)([] {
+    return oatpp::network::tcp::server::ConnectionProvider::createShared({"0.0.0.0", 8000, oatpp::network::Address::IP_4});
+  }());
+  
+  /**
+   *  Create Router component
+   */
+  OATPP_CREATE_COMPONENT(std::shared_ptr<oatpp::web::server::HttpRouter>, httpRouter)([] {
+    return oatpp::web::server::HttpRouter::createShared();
+  }());
+  
+  /**
+   *  Create ConnectionHandler component which uses Router component to route requests
+   */
+  OATPP_CREATE_COMPONENT(std::shared_ptr<oatpp::network::ConnectionHandler>, serverConnectionHandler)([] {
+
+    OATPP_COMPONENT(std::shared_ptr<oatpp::web::server::HttpRouter>, router); // get Router component
+    OATPP_COMPONENT(std::shared_ptr<oatpp::data::mapping::ObjectMapper>, objectMapper); // get ObjectMapper component
+
+    auto connectionHandler = oatpp::web::server::HttpConnectionHandler::createShared(router);
+    connectionHandler->setErrorHandler(std::make_shared<ErrorHandler>(objectMapper));
+    return connectionHandler;
+
+  }());
+
+};
+
+#endif /* AppComponent_hpp */