json formatting settable from outside

README.md

@@ -54,40 +54,40 @@ Result:
 ```json
 {
  "base" : "EUR",
- "date" : "2024-03-22",
+ "date" : "2024-03-27",
  "rates" :
  {
-  "AUD" : 1.6600999999999999,
-  "BGN" : 1.9558,
-  "BRL" : 5.4099000000000004,
-  "CAD" : 1.4688000000000001,
-  "CHF" : 0.97289999999999999,
-  "CNY" : 7.8244999999999996,
-  "CZK" : 25.370999999999999,
-  "DKK" : 7.4581,
-  "GBP" : 0.85794999999999999,
-  "HKD" : 8.4644999999999992,
-  "HUF" : 396.30000000000001,
-  "IDR" : 17111.810000000001,
-  "ILS" : 3.9264999999999999,
-  "INR" : 90.409000000000006,
-  "ISK" : 148.90000000000001,
-  "JPY" : 163.74000000000001,
-  "KRW" : 1453.6199999999999,
-  "MXN" : 18.1372,
-  "MYR" : 5.1273999999999997,
-  "NOK" : 11.617000000000001,
-  "NZD" : 1.802,
-  "PHP" : 60.927999999999997,
-  "PLN" : 4.3170000000000002,
-  "RON" : 4.9726999999999997,
-  "SEK" : 11.4025,
-  "SGD" : 1.4593,
-  "THB" : 39.298000000000002,
-  "TRY" : 34.620899999999999,
-  "USD" : 1.0823,
-  "ZAR" : 20.559699999999999
- },
+    "AUD" : 1.66,
+    "BGN" : 1.9558,
+    "BRL" : 5.3969,
+    "CAD" : 1.4712,
+    "CHF" : 0.9811,
+    "CNY" : 7.8182,
+    "CZK" : 25.319,
+    "DKK" : 7.4582,
+    "GBP" : 0.85768,
+    "HKD" : 8.4615,
+    "HUF" : 395.4,
+    "IDR" : 17194.2,
+    "ILS" : 3.9582,
+    "INR" : 90.134,
+    "ISK" : 149.9,
+    "JPY" : 163.52,
+    "KRW" : 1461.31,
+    "MXN" : 17.9367,
+    "MYR" : 5.1192,
+    "NOK" : 11.6825,
+    "NZD" : 1.8043,
+    "PHP" : 60.849,
+    "PLN" : 4.3148,
+    "RON" : 4.9721,
+    "SEK" : 11.506,
+    "SGD" : 1.4586,
+    "THB" : 39.381,
+    "TRY" : 34.9005,
+    "USD" : 1.0816,
+    "ZAR" : 20.4716
+  },
  "success" : true
 }
 ```
@@ -102,14 +102,14 @@ Result:
 
 ```json
 {
- "base" : "USD",
- "date" : "2024-03-22",
- "rates" :
- {
-  "DKK" : 6.8909729280236531,
-  "EUR" : 0.92395823708768365,
-  "NOK" : 10.733622840247621
- },
- "success" : true
+  "base" : "USD",
+  "date" : "2024-03-27",
+  "rates" :
+  {
+    "DKK" : 6.89553,
+    "EUR" : 0.924556,
+    "NOK" : 10.8011
+  },
+  "success" : true
 }
 ```

TODO

@@ -1,9 +1,7 @@
+
 - use cmake presets
-- github actions for tests
 - target with asan
 - examples of configuration (nginx, cron)
-- json output - no so verbose if needed
-- json output - floats limited to 4 decimal places
 - make cross compilation work again
 - consider removing ECB namespace
 - consider using spdlog

src/Main_Server.cpp

@@ -37,7 +37,13 @@ int main(int argc, char *argv[])
         return num >= 1 && num <= 65535; // NOLINT
     });
 
+    options.add_optional("precision", "Numerical precision of rates: 1..20", "6", [](const std::string &value) {
+        uint32_t num = Options::as_uint(value);
+        return num >= 1 && num <= 20; // NOLINT
+    });
+
     options.add_flag("listen_all", "Listen on all interfaces");
+    options.add_flag("pretty", "Pretty print JSON output");
     options.add_flag("help", "Show help");
 
     const bool parse_result = options.parse(argc, argv);
@@ -83,10 +89,16 @@ int main(int argc, char *argv[])
     Main_Signals::Setup(); // handling SIGINT and SIGUSR1
 
     const uint16_t port = options.as_uint("port");
+    const uint16_t precision = options.as_uint("precision");
     const bool listen_all = options.as_bool("listen_all");
+    const bool pretty = options.as_bool("pretty");
     cout << "Starting server on port " << port << (listen_all ? " on all interfaces" : " on localhost only") << endl;
+    cout << "Pretty JSON output: " << (pretty ? "yes" : "no") << endl;
+    cout << "Numerical precision: " << precision << endl;
 
     auto &server = ECB::Server::Instance();
+    server.SetPrettyJson(pretty);
+    server.SetPrecision(precision);
 
     if (!server.Initialize(rates, port, listen_all))
     {

src/Main_Signals.cpp

@@ -2,7 +2,7 @@
 
 #include <csignal>
 
-volatile bool Main_Signals::m_keep_running = true; // NOLINT
+volatile bool Main_Signals::m_keep_running = true;    // NOLINT
 volatile bool Main_Signals::m_load_more_data = false; // NOLINT
 
 void Main_Signals::Setup()

src/Server.cpp

@@ -19,6 +19,9 @@ namespace ECB
         return m_impl->initialize(ecb, listening_address);
     }
 
+    void Server::SetPrettyJson(bool pretty) { m_impl->set_pretty_json(pretty); }
+    void Server::SetPrecision(uint16_t precision) { m_impl->set_precision(precision); }
+
     void Server::Start() { m_impl->start_polling(); }
 
     void Server::Stop() { m_impl->stop_polling(); }

src/Server.hpp

@@ -23,6 +23,10 @@ namespace ECB
 
         bool Initialize(std::shared_ptr<Rates> ecb, uint16_t port, bool listen_all);
 
+        void SetPrettyJson(bool pretty);
+
+        void SetPrecision(uint16_t precision);
+
         void Start();
 
         void Stop();

src/Server_Impl.cpp

@@ -9,7 +9,12 @@
 
 namespace ECB
 {
-    Server_Impl::Server_Impl() { mg_mgr_init(&m_mgr); }
+    Server_Impl::Server_Impl()
+    {
+        mg_mgr_init(&m_mgr);
+        m_json_builder["indentation"] = "";
+        m_json_builder["precision"] = 6; // default is 17
+    }
 
     Server_Impl::~Server_Impl() { mg_mgr_free(&m_mgr); }
 
@@ -83,10 +88,7 @@ namespace ECB
             }
         }
 
-        std::stringstream ss;
-
-        ss << ans;
-        return ss.str();
+        return Json::writeString(m_json_builder, ans);
     }
 
     std::string Server_Impl::print_error(const std::string &msg) const
@@ -95,10 +97,8 @@ namespace ECB
 
         ans["success"] = false;
         ans["error_text"] = msg;
-        std::stringstream ss;
 
-        ss << ans;
-        return ss.str();
+        return Json::writeString(m_json_builder, ans);
     }
 
     void Server_Impl::handler(mg_connection *connection, int event, void *event_data)

src/Server_Impl.hpp

@@ -3,6 +3,7 @@
 #include "Symbol.hpp"
 
 #include "mongoose.h"
+#include "json/json.h"
 
 #include <memory>
 #include <string>
@@ -20,6 +21,8 @@ namespace ECB
         ~Server_Impl();
 
         bool initialize(std::shared_ptr<Rates> rates, const std::string &listen_address);
+        void set_pretty_json(bool pretty) { m_json_builder["indentation"] = pretty ? "  " : ""; }
+        void set_precision(uint16_t precision) { m_json_builder["precision"] = precision; }
 
         void start_polling();
         void stop_polling() { m_running = false; }
@@ -36,6 +39,7 @@ namespace ECB
         struct mg_connection *m_conn = nullptr;
         bool m_running = false;
         std::shared_ptr<Rates> m_rates;
+        Json::StreamWriterBuilder m_json_builder;
 
         // must be static to be used as a callback for mongoose
         static void handler(mg_connection *connection, int event, void *event_data);