Added support for custom converters (closes #687)

extras/tests/JsonVariant/converters.cpp

@@ -0,0 +1,144 @@
+// ArduinoJson - arduinojson.org
+// Copyright Benoit Blanchon 2014-2021
+// MIT License
+
+#include <ArduinoJson.h>
+#include <stdint.h>
+#include <catch.hpp>
+
+namespace {
+struct Date {
+  int day;
+  int month;
+  int year;
+};
+
+bool convertToJson(JsonVariant variant, const Date& date) {
+  variant["day"] = date.day;
+  variant["month"] = date.month;
+  variant["year"] = date.year;
+  return true;
+}
+
+void convertFromJson(Date& date, JsonVariantConst variant) {
+  date.day = variant["day"];
+  date.month = variant["month"];
+  date.year = variant["year"];
+}
+
+bool canConvertFromJson(Date&, JsonVariantConst variant) {
+  return variant["day"].is<int>() && variant["month"].is<int>() &&
+         variant["year"].is<int>();
+}
+}  // namespace
+
+TEST_CASE("Custom converter with overloading") {
+  DynamicJsonDocument doc(4096);
+
+  SECTION("convert JSON to Date") {
+    doc["date"]["day"] = 2;
+    doc["date"]["month"] = 3;
+    doc["date"]["year"] = 2021;
+
+    Date date = doc["date"];
+
+    REQUIRE(date.day == 2);
+    REQUIRE(date.month == 3);
+    REQUIRE(date.year == 2021);
+  }
+
+  SECTION("is<Date>() returns true") {
+    doc["date"]["day"] = 2;
+    doc["date"]["month"] = 3;
+    doc["date"]["year"] = 2021;
+
+    REQUIRE(doc["date"].is<Date>());
+  }
+
+  SECTION("is<Date>() returns false") {
+    doc["date"]["day"] = 2;
+    doc["date"]["month"] = 3;
+    doc["date"]["year"] = "2021";
+
+    REQUIRE(doc["date"].is<Date>() == false);
+  }
+
+  SECTION("convert Date to JSON") {
+    Date date = {19, 3, 2021};
+    doc["date"] = date;
+
+    REQUIRE(doc["date"]["day"] == 19);
+    REQUIRE(doc["date"]["month"] == 3);
+    REQUIRE(doc["date"]["year"] == 2021);
+  }
+}
+
+class Complex {
+ public:
+  explicit Complex(double r, double i) : _real(r), _imag(i) {}
+
+  double real() const {
+    return _real;
+  }
+
+  double imag() const {
+    return _imag;
+  }
+
+ private:
+  double _real, _imag;
+};
+
+namespace ARDUINOJSON_NAMESPACE {
+template <>
+struct Converter<Complex> {
+  static bool toJson(VariantRef variant, const Complex& value) {
+    variant["real"] = value.real();
+    variant["imag"] = value.imag();
+    return true;
+  }
+
+  static Complex fromJson(VariantConstRef variant) {
+    return Complex(variant["real"], variant["imag"]);
+  }
+
+  static bool checkJson(VariantConstRef variant) {
+    return variant["real"].is<double>() && variant["imag"].is<double>();
+  }
+};
+}  // namespace ARDUINOJSON_NAMESPACE
+
+TEST_CASE("Custom converter with specialization") {
+  DynamicJsonDocument doc(4096);
+
+  SECTION("convert JSON to Complex") {
+    doc["value"]["real"] = 2;
+    doc["value"]["imag"] = 3;
+
+    Complex value = doc["value"];
+
+    REQUIRE(value.real() == 2);
+    REQUIRE(value.imag() == 3);
+  }
+
+  SECTION("is<Complex>() returns true") {
+    doc["value"]["real"] = 2;
+    doc["value"]["imag"] = 3;
+
+    REQUIRE(doc["value"].is<Complex>());
+  }
+
+  SECTION("is<Complex>() returns false") {
+    doc["value"]["real"] = 2;
+    doc["value"]["imag"] = "3";
+
+    REQUIRE(doc["value"].is<Complex>() == false);
+  }
+
+  SECTION("convert value to JSON") {
+    doc["value"] = Complex(19, 3);
+
+    REQUIRE(doc["value"]["real"] == 19);
+    REQUIRE(doc["value"]["imag"] == 3);
+  }
+}