Added an example for uploading files

Relates to issue #591.

examples/CMakeLists.txt

@@ -89,6 +89,10 @@ add_executable(example_session middlewares/example_session.cpp)
 add_warnings_optimizations(example_session)
 target_link_libraries(example_session PUBLIC Crow::Crow)
 
+add_executable(example_file_upload example_file_upload.cpp)
+add_warnings_optimizations(example_file_upload)
+target_link_libraries(example_file_upload PUBLIC Crow::Crow)
+
 if(MSVC)
   add_executable(example_vs example_vs.cpp)
   add_warnings_optimizations(example_vs)

examples/example_file_upload.cpp

@@ -0,0 +1,72 @@
+#include "crow.h"
+
+int main()
+{
+    crow::SimpleApp app;
+
+    CROW_ROUTE(app, "/uploadfile")
+      .methods(crow::HTTPMethod::Post)([](const crow::request& req) {
+          crow::multipart::message file_message(req);
+          for (const auto& part : file_message.part_map)
+          {
+              const auto& part_name = part.first;
+              const auto& part_value = part.second;
+              CROW_LOG_DEBUG << "Part: " << part_name;
+              if ("InputFile" == part_name)
+              {
+                  // Extract the file name
+                  auto headers_it = part_value.headers.find("Content-Disposition");
+                  if (headers_it == part_value.headers.end())
+                  {
+                      CROW_LOG_ERROR << "No Content-Disposition found";
+                      return crow::response(400);
+                  }
+                  auto params_it = headers_it->second.params.find("filename");
+                  if (params_it == headers_it->second.params.end())
+                  {
+                      CROW_LOG_ERROR << "Part with name \"InputFile\" should have a file";
+                      return crow::response(400);
+                  }
+                  const std::string outfile_name = params_it->second;
+
+                  for (const auto& part_header : part_value.headers)
+                  {
+                      const auto& part_header_name = part_header.first;
+                      const auto& part_header_val = part_header.second;
+                      CROW_LOG_DEBUG << "Header: " << part_header_name << '=' << part_header_val.value;
+                      for (const auto& param : part_header_val.params)
+                      {
+                          const auto& param_key = param.first;
+                          const auto& param_val = param.second;
+                          CROW_LOG_DEBUG << " Param: " << param_key << ',' << param_val;
+                      }
+                  }
+
+                  // Create a new file with the extracted file name and write file contents to it
+                  std::ofstream out_file(outfile_name);
+                  if (!out_file)
+                  {
+                      CROW_LOG_ERROR << " Write to file failed\n";
+                      continue;
+                  }
+                  out_file << part_value.body;
+                  out_file.close();
+                  CROW_LOG_INFO << " Contents written to " << outfile_name << '\n';
+              }
+              else
+              {
+                  CROW_LOG_DEBUG << " Value: " << part_value.body << '\n';
+              }
+          }
+          return crow::response(200);
+      });
+
+    // enables all log
+    app.loglevel(crow::LogLevel::Debug);
+
+    app.port(18080)
+      .multithreaded()
+      .run();
+
+    return 0;
+}