args_processing.cpp

/*
 This file is part of libhttpserver
 Copyright (C) 2011-2025 Sebastiano Merlino

 This library is free software; you can redistribute it and/or
 modify it under the terms of the GNU Lesser General Public
 License as published by the Free Software Foundation; either
 version 2.1 of the License, or (at your option) any later version.

 This library is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 Lesser General Public License for more details.

 You should have received a copy of the GNU Lesser General Public
 License along with this library; if not, write to the Free Software
 Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301
 USA
*/

// args_processing.cpp - demonstrates get_args() and get_args_flat() to
// process all query string and body arguments from an HTTP request.
//
// Try these URLs:
// http://localhost:8080/args?name=john&age=30
// http://localhost:8080/args?id=1&id=2&id=3 (multiple values for same key)
// http://localhost:8080/args?colors=red&colors=green&colors=blue

#include <iostream>
#include <sstream>
#include <string>
#include <string_view>

#include <httpserver.hpp>

int main() {
 httpserver::webserver ws{httpserver::create_webserver(8080)};

 ws.on_get("/args", [](const httpserver::http_request& req) {
 std::ostringstream response_body;

 response_body << "=== Using get_args() (supports multiple values per key) ===\n\n";

 // get_args() returns a const reference to a map where each key
 // maps to an http_arg_value. http_arg_value contains a vector of
 // values for parameters like "?id=1&id=2&id=3". The reference
 // remains valid for the duration of this handler call.
 const auto& args = req.get_args();
 for (const auto& [key, arg_value] : args) {
 response_body << "Key: " << key << "\n";
 // Use get_all_values() to get all values for this key
 auto all_values = arg_value.get_all_values();
 if (all_values.size() > 1) {
 response_body << " Values (" << all_values.size() << "):\n";
 for (const auto& v : all_values) {
 response_body << " - " << v << "\n";
 }
 } else {
 // For single values, http_arg_value converts to string_view
 response_body << " Value: " << std::string_view(arg_value) << "\n";
 }
 }

 response_body << "\n=== Using get_args_flat() (one value per key) ===\n\n";

 // get_args_flat() returns a simple map with one value per key.
 // If a key has multiple values, only the first value is returned.
 auto args_flat = req.get_args_flat();
 for (const auto& [key, value] : args_flat) {
 response_body << key << " = " << value << "\n";
 }

 response_body << "\n=== Accessing individual arguments ===\n\n";

 // You can also access individual arguments directly
 auto name = req.get_arg("name"); // Returns http_arg_value (may have multiple values)
 auto name_flat = req.get_arg_flat("name"); // Returns string_view (first value only)

 if (!name.get_flat_value().empty()) {
 response_body << "name (via get_arg): " << std::string_view(name) << "\n";
 }
 if (!name_flat.empty()) {
 response_body << "name (via get_arg_flat): " << name_flat << "\n";
 }

 return httpserver::http_response::string(response_body.str());
 });

 std::cout << "Server running on http://localhost:8080/args\n";
 std::cout << "Try: http://localhost:8080/args?name=john&age=30\n";
 std::cout << "Or: http://localhost:8080/args?id=1&id=2&id=3\n";

 ws.start(true);
 return 0;
}