diff --git a/src/json.hpp b/src/json.hpp
index 2dfa7c02..fc7781ea 100644
--- a/src/json.hpp
+++ b/src/json.hpp
@@ -257,6 +257,30 @@ struct is_compatible_integer_type_impl<true, RealIntegerType, CompatibleNumberIn
       RealLimits::is_signed == CompatibleLimits::is_signed;
 };
 
+// quickfix, just trying to make things compile before refactoring
+template <bool B, typename RealIntegerType, typename CompatibleEnumType>
+struct is_compatible_enum_type_impl : std::false_type{};
+
+template <typename RealIntegerType, typename CompatibleEnumType>
+struct is_compatible_enum_type_impl<true, RealIntegerType, CompatibleEnumType>
+{
+  using RealLimits = std::numeric_limits<RealIntegerType>;
+  using CompatibleLimits = std::numeric_limits<typename std::underlying_type<CompatibleEnumType>::type>;
+
+  static constexpr auto value =
+      CompatibleLimits::is_integer and
+      RealLimits::is_signed == CompatibleLimits::is_signed;
+};
+
+template <typename RealIntegerType, typename CompatibleEnumType>
+struct is_compatible_enum_type
+{
+  static constexpr auto value = is_compatible_enum_type_impl<
+// quickfix for all enums
+      std::is_enum<CompatibleEnumType>::value, RealIntegerType,
+      CompatibleEnumType>::value;
+};
+
 template <typename RealIntegerType, typename CompatibleNumberIntegerType>
 struct is_compatible_integer_type
 {
@@ -281,6 +305,7 @@ struct is_compatible_basic_json_type
       std::is_constructible<typename BasicJson::string_t, T>::value or
       std::is_same<typename BasicJson::boolean_t, T>::value or
       is_compatible_array_type<BasicJson, T>::value or
+      is_compatible_enum_type<T, typename BasicJson::number_integer_t>::value or
       is_compatible_object_type<typename BasicJson::object_t, T>::value or
       is_compatible_float_type<typename BasicJson::number_float_t, T>::value or
       is_compatible_integer_type<typename BasicJson::number_integer_t,
@@ -289,6 +314,16 @@ struct is_compatible_basic_json_type
                                  T>::value;
 };
 
+template <typename T, typename BasicJson, typename PrimitiveIterator>
+struct is_basic_json_nested_class
+{
+  static auto constexpr value = std::is_same<T, typename BasicJson::iterator>::value or
+                                std::is_same<T, typename BasicJson::const_iterator>::value or
+                                std::is_same<T, typename BasicJson::reverse_iterator>::value or
+                                std::is_same<T, typename BasicJson::const_reverse_iterator>::value or
+                                std::is_same<T, PrimitiveIterator>::value or
+                                std::is_same<T, typename BasicJson::json_pointer>::value;
+};
 
 // This trait checks if JSONSerializer<T>::from_json(json const&, udt&) exists
 template <template <typename, typename> class JSONSerializer, typename Json,
@@ -344,8 +379,8 @@ public:
 
 // those declarations are needed to workaround a MSVC bug related to ADL
 // (taken from MSVC-Ranges implementation)
-//void to_json();
-//void from_json();
+void to_json();
+void from_json();
 
 struct to_json_fn
 {
@@ -524,6 +559,7 @@ class basic_json
     using basic_json_t = basic_json<ObjectType, ArrayType, StringType,
           BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType,
           AllocatorType, JSONSerializer>;
+    class primitive_iterator_t;
 
   public:
     // forward declarations
@@ -1589,10 +1625,15 @@ class basic_json
         enable_if_t<not std::is_base_of<std::istream, uncvref_t<T>>::value and
                         not detail::is_compatible_basic_json_type<
                             uncvref_t<T>, basic_json_t>::value and
+                        not detail::is_basic_json_nested_class<uncvref_t<T>, basic_json_t, primitive_iterator_t>::value and
+                        not std::is_same<uncvref_t<T>, typename basic_json_t::array_t::iterator>::value and
+// quickfix
+not std::is_enum<uncvref_t<T>>::value and
+                        not std::is_same<uncvref_t<T>, typename basic_json_t::object_t::iterator>::value and
                         detail::has_to_json<JSONSerializer, basic_json,
                                             uncvref_t<T>>::value,
                     int> = 0>
-    explicit basic_json(T &&val)
+    basic_json(T &&val)
     {
       JSONSerializer<uncvref_t<T>>::to_json(*this, std::forward<T>(val));
     }
@@ -1793,7 +1834,8 @@ class basic_json
     template <
         typename CompatibleNumberIntegerType,
         enable_if_t<detail::is_compatible_integer_type<
-                        number_integer_t, CompatibleNumberIntegerType>::value,
+                        number_integer_t, CompatibleNumberIntegerType>::value or
+detail::is_compatible_enum_type<number_integer_t, CompatibleNumberIntegerType>::value,
                     int> = 0>
     basic_json(const CompatibleNumberIntegerType val) noexcept
         : m_type(value_t::number_integer),
@@ -8502,6 +8544,11 @@ class basic_json
     class primitive_iterator_t
     {
       public:
+
+        difference_type get_value() const noexcept
+        {
+          return m_it;
+        }
         /// set iterator to a defined beginning
         void set_begin() noexcept
         {
@@ -8526,16 +8573,85 @@ class basic_json
             return (m_it == end_value);
         }
 
-        /// return reference to the value to change and compare
-        operator difference_type& () noexcept
+        friend constexpr bool operator==(primitive_iterator_t lhs, primitive_iterator_t rhs) noexcept
         {
-            return m_it;
+          return lhs.m_it == rhs.m_it;
         }
 
-        /// return value to compare
-        constexpr operator difference_type () const noexcept
+        friend constexpr bool operator!=(primitive_iterator_t lhs, primitive_iterator_t rhs) noexcept
         {
-            return m_it;
+          return !(lhs == rhs);
+        }
+
+        friend constexpr bool operator<(primitive_iterator_t lhs, primitive_iterator_t rhs) noexcept
+        {
+          return lhs.m_it < rhs.m_it;
+        }
+
+        friend constexpr bool operator<=(primitive_iterator_t lhs, primitive_iterator_t rhs) noexcept
+        {
+          return lhs.m_it <= rhs.m_it;
+        }
+
+        friend constexpr bool operator>(primitive_iterator_t lhs, primitive_iterator_t rhs) noexcept
+        {
+          return lhs.m_it > rhs.m_it;
+        }
+
+        friend constexpr bool operator>=(primitive_iterator_t lhs, primitive_iterator_t rhs) noexcept
+        {
+          return lhs.m_it >= rhs.m_it;
+        }
+
+        friend constexpr bool operator+(primitive_iterator_t lhs, primitive_iterator_t rhs) noexcept
+        {
+          return lhs.m_it + rhs.m_it;
+        }
+
+        friend constexpr bool operator-(primitive_iterator_t lhs, primitive_iterator_t rhs) noexcept
+        {
+          return lhs.m_it - rhs.m_it;
+        }
+
+        friend std::ostream& operator<<(std::ostream& os, primitive_iterator_t it)
+        {
+          return os << it.m_it;
+        }
+
+        primitive_iterator_t& operator++()
+        {
+          ++m_it;
+          return *this;
+        }
+
+        primitive_iterator_t& operator++(int)
+        {
+          m_it++;
+          return *this;
+        }
+
+        primitive_iterator_t& operator--()
+        {
+          --m_it;
+          return *this;
+        }
+
+        primitive_iterator_t& operator--(int)
+        {
+          m_it--;
+          return *this;
+        }
+
+        primitive_iterator_t& operator+=(difference_type n)
+        {
+          m_it += n;
+          return *this;
+        }
+
+        primitive_iterator_t& operator-=(difference_type n)
+        {
+          m_it -= n;
+          return *this;
         }
 
       private:
@@ -9240,7 +9356,7 @@ class basic_json
 
                 default:
                 {
-                    if (m_it.primitive_iterator == -n)
+                    if (m_it.primitive_iterator.get_value() == -n)
                     {
                         return *m_object;
                     }
diff --git a/test/src/unit-class_const_iterator.cpp b/test/src/unit-class_const_iterator.cpp
index 13ce7c3f..a1f6b827 100644
--- a/test/src/unit-class_const_iterator.cpp
+++ b/test/src/unit-class_const_iterator.cpp
@@ -220,20 +220,20 @@ TEST_CASE("const_iterator class")
             {
                 json j(json::value_t::null);
                 json::const_iterator it = j.cbegin();
-                CHECK(it.m_it.primitive_iterator == 1);
+                CHECK(it.m_it.primitive_iterator.m_it == 1);
                 it++;
-                CHECK((it.m_it.primitive_iterator != 0 and it.m_it.primitive_iterator != 1));
+                CHECK((it.m_it.primitive_iterator.m_it != 0 and it.m_it.primitive_iterator.m_it != 1));
             }
 
             SECTION("number")
             {
                 json j(17);
                 json::const_iterator it = j.cbegin();
-                CHECK(it.m_it.primitive_iterator == 0);
+                CHECK(it.m_it.primitive_iterator.m_it == 0);
                 it++;
-                CHECK(it.m_it.primitive_iterator == 1);
+                CHECK(it.m_it.primitive_iterator.m_it == 1);
                 it++;
-                CHECK((it.m_it.primitive_iterator != 0 and it.m_it.primitive_iterator != 1));
+                CHECK((it.m_it.primitive_iterator.m_it != 0 and it.m_it.primitive_iterator.m_it != 1));
             }
 
             SECTION("object")
@@ -271,20 +271,20 @@ TEST_CASE("const_iterator class")
             {
                 json j(json::value_t::null);
                 json::const_iterator it = j.cbegin();
-                CHECK(it.m_it.primitive_iterator == 1);
+                CHECK(it.m_it.primitive_iterator.m_it == 1);
                 ++it;
-                CHECK((it.m_it.primitive_iterator != 0 and it.m_it.primitive_iterator != 1));
+                CHECK((it.m_it.primitive_iterator.m_it != 0 and it.m_it.primitive_iterator.m_it != 1));
             }
 
             SECTION("number")
             {
                 json j(17);
                 json::const_iterator it = j.cbegin();
-                CHECK(it.m_it.primitive_iterator == 0);
+                CHECK(it.m_it.primitive_iterator.m_it == 0);
                 ++it;
-                CHECK(it.m_it.primitive_iterator == 1);
+                CHECK(it.m_it.primitive_iterator.m_it == 1);
                 ++it;
-                CHECK((it.m_it.primitive_iterator != 0 and it.m_it.primitive_iterator != 1));
+                CHECK((it.m_it.primitive_iterator.m_it != 0 and it.m_it.primitive_iterator.m_it != 1));
             }
 
             SECTION("object")
@@ -322,18 +322,18 @@ TEST_CASE("const_iterator class")
             {
                 json j(json::value_t::null);
                 json::const_iterator it = j.cend();
-                CHECK(it.m_it.primitive_iterator == 1);
+                CHECK(it.m_it.primitive_iterator.m_it == 1);
             }
 
             SECTION("number")
             {
                 json j(17);
                 json::const_iterator it = j.cend();
-                CHECK(it.m_it.primitive_iterator == 1);
+                CHECK(it.m_it.primitive_iterator.m_it == 1);
                 it--;
-                CHECK(it.m_it.primitive_iterator == 0);
+                CHECK(it.m_it.primitive_iterator.m_it == 0);
                 it--;
-                CHECK((it.m_it.primitive_iterator != 0 and it.m_it.primitive_iterator != 1));
+                CHECK((it.m_it.primitive_iterator.m_it != 0 and it.m_it.primitive_iterator.m_it != 1));
             }
 
             SECTION("object")
@@ -371,18 +371,18 @@ TEST_CASE("const_iterator class")
             {
                 json j(json::value_t::null);
                 json::const_iterator it = j.cend();
-                CHECK(it.m_it.primitive_iterator == 1);
+                CHECK(it.m_it.primitive_iterator.m_it == 1);
             }
 
             SECTION("number")
             {
                 json j(17);
                 json::const_iterator it = j.cend();
-                CHECK(it.m_it.primitive_iterator == 1);
+                CHECK(it.m_it.primitive_iterator.m_it == 1);
                 --it;
-                CHECK(it.m_it.primitive_iterator == 0);
+                CHECK(it.m_it.primitive_iterator.m_it == 0);
                 --it;
-                CHECK((it.m_it.primitive_iterator != 0 and it.m_it.primitive_iterator != 1));
+                CHECK((it.m_it.primitive_iterator.m_it != 0 and it.m_it.primitive_iterator.m_it != 1));
             }
 
             SECTION("object")
diff --git a/test/src/unit-class_iterator.cpp b/test/src/unit-class_iterator.cpp
index 640bc816..1e8a3cec 100644
--- a/test/src/unit-class_iterator.cpp
+++ b/test/src/unit-class_iterator.cpp
@@ -204,20 +204,20 @@ TEST_CASE("iterator class")
             {
                 json j(json::value_t::null);
                 json::iterator it = j.begin();
-                CHECK(it.m_it.primitive_iterator == 1);
+                CHECK(it.m_it.primitive_iterator.m_it == 1);
                 it++;
-                CHECK((it.m_it.primitive_iterator != 0 and it.m_it.primitive_iterator != 1));
+                CHECK((it.m_it.primitive_iterator.m_it != 0 and it.m_it.primitive_iterator.m_it != 1));
             }
 
             SECTION("number")
             {
                 json j(17);
                 json::iterator it = j.begin();
-                CHECK(it.m_it.primitive_iterator == 0);
+                CHECK(it.m_it.primitive_iterator.m_it == 0);
                 it++;
-                CHECK(it.m_it.primitive_iterator == 1);
+                CHECK(it.m_it.primitive_iterator.m_it == 1);
                 it++;
-                CHECK((it.m_it.primitive_iterator != 0 and it.m_it.primitive_iterator != 1));
+                CHECK((it.m_it.primitive_iterator.m_it != 0 and it.m_it.primitive_iterator.m_it != 1));
             }
 
             SECTION("object")
@@ -255,20 +255,20 @@ TEST_CASE("iterator class")
             {
                 json j(json::value_t::null);
                 json::iterator it = j.begin();
-                CHECK(it.m_it.primitive_iterator == 1);
+                CHECK(it.m_it.primitive_iterator.m_it == 1);
                 ++it;
-                CHECK((it.m_it.primitive_iterator != 0 and it.m_it.primitive_iterator != 1));
+                CHECK((it.m_it.primitive_iterator.m_it != 0 and it.m_it.primitive_iterator.m_it != 1));
             }
 
             SECTION("number")
             {
                 json j(17);
                 json::iterator it = j.begin();
-                CHECK(it.m_it.primitive_iterator == 0);
+                CHECK(it.m_it.primitive_iterator.m_it == 0);
                 ++it;
-                CHECK(it.m_it.primitive_iterator == 1);
+                CHECK(it.m_it.primitive_iterator.m_it == 1);
                 ++it;
-                CHECK((it.m_it.primitive_iterator != 0 and it.m_it.primitive_iterator != 1));
+                CHECK((it.m_it.primitive_iterator.m_it != 0 and it.m_it.primitive_iterator.m_it != 1));
             }
 
             SECTION("object")
@@ -306,18 +306,18 @@ TEST_CASE("iterator class")
             {
                 json j(json::value_t::null);
                 json::iterator it = j.end();
-                CHECK(it.m_it.primitive_iterator == 1);
+                CHECK(it.m_it.primitive_iterator.m_it == 1);
             }
 
             SECTION("number")
             {
                 json j(17);
                 json::iterator it = j.end();
-                CHECK(it.m_it.primitive_iterator == 1);
+                CHECK(it.m_it.primitive_iterator.m_it == 1);
                 it--;
-                CHECK(it.m_it.primitive_iterator == 0);
+                CHECK(it.m_it.primitive_iterator.m_it == 0);
                 it--;
-                CHECK((it.m_it.primitive_iterator != 0 and it.m_it.primitive_iterator != 1));
+                CHECK((it.m_it.primitive_iterator.m_it != 0 and it.m_it.primitive_iterator.m_it != 1));
             }
 
             SECTION("object")
@@ -355,18 +355,18 @@ TEST_CASE("iterator class")
             {
                 json j(json::value_t::null);
                 json::iterator it = j.end();
-                CHECK(it.m_it.primitive_iterator == 1);
+                CHECK(it.m_it.primitive_iterator.m_it == 1);
             }
 
             SECTION("number")
             {
                 json j(17);
                 json::iterator it = j.end();
-                CHECK(it.m_it.primitive_iterator == 1);
+                CHECK(it.m_it.primitive_iterator.m_it == 1);
                 --it;
-                CHECK(it.m_it.primitive_iterator == 0);
+                CHECK(it.m_it.primitive_iterator.m_it == 0);
                 --it;
-                CHECK((it.m_it.primitive_iterator != 0 and it.m_it.primitive_iterator != 1));
+                CHECK((it.m_it.primitive_iterator.m_it != 0 and it.m_it.primitive_iterator.m_it != 1));
             }
 
             SECTION("object")
diff --git a/test/src/unit-udt.cpp b/test/src/unit-udt.cpp
index cd9ec1c4..28443344 100644
--- a/test/src/unit-udt.cpp
+++ b/test/src/unit-udt.cpp
@@ -37,35 +37,35 @@ namespace udt
 {
   struct age
   {
-    int val;
+    int m_val;
   };
 
   struct name
   {
-    std::string val;
+    std::string m_val;
   };
 
   struct address
   {
-    std::string val;
+    std::string m_val;
   };
 
   struct person
   {
-    age age;
-    name name;
+    age m_age;
+    name m_name;
   };
 
   struct contact
   {
-    person person;
-    address address;
+    person m_person;
+    address m_address;
   };
 
   struct contact_book
   {
-    name book_name;
-    std::vector<contact> contacts;
+    name m_book_name;
+    std::vector<contact> m_contacts;
   };
 }
 
@@ -74,39 +74,105 @@ namespace udt
 {
   void to_json(nlohmann::json& j, age a)
   {
-    j = a.val;
+    j = a.m_val;
   }
 
   void to_json(nlohmann::json& j, name const& n)
   {
-    j = n.val;
+    j = n.m_val;
   }
 
   void to_json(nlohmann::json& j, person const& p)
   {
     using nlohmann::json;
-    j = json{{"age", json{p.age}}, {"name", json{p.name}}};
-
-    // this unfortunately does not compile ...
-    // j["age"] = p.age;
-    // j["name"] = p.name;
+    j = json{{"age", json{p.m_age}}, {"name", json{p.m_name}}};
   }
 
   void to_json(nlohmann::json& j, address const& a)
   {
-    j = a.val;
+    j = a.m_val;
   }
 
   void to_json(nlohmann::json& j, contact const& c)
   {
     using nlohmann::json;
-    j = json{{"person", json{c.person}}, {"address", json{c.address}}};
+    j = json{{"person", json{c.m_person}}, {"address", json{c.m_address}}};
   }
 
   void to_json(nlohmann::json& j, contact_book const& cb)
   {
     using nlohmann::json;
-    j = json{{"name", json{cb.book_name}}, {"contacts", cb.contacts}};
+    j = json{{"name", json{cb.m_book_name}}, {"contacts", cb.m_contacts}};
+  }
+
+  // operators
+  bool operator==(age lhs, age rhs)
+  {
+    return lhs.m_val == rhs.m_val;
+  }
+
+  bool operator==(address const &lhs, address const &rhs)
+  {
+    return lhs.m_val == rhs.m_val;
+  }
+
+  bool operator==(name const &lhs, name const &rhs)
+  {
+    return lhs.m_val == rhs.m_val;
+  }
+
+  bool operator==(person const &lhs, person const &rhs)
+  {
+    return std::tie(lhs.m_name, lhs.m_age) == std::tie(rhs.m_name, rhs.m_age);
+  }
+
+  bool operator==(contact const &lhs, contact const &rhs)
+  {
+    return std::tie(lhs.m_person, lhs.m_address) ==
+           std::tie(rhs.m_person, rhs.m_address);
+  }
+
+  bool operator==(contact_book const &lhs, contact_book const &rhs)
+  {
+    return std::tie(lhs.m_book_name, lhs.m_contacts) ==
+           std::tie(rhs.m_book_name, rhs.m_contacts);
+  }
+}
+
+// from_json methods for default basic_json
+namespace udt
+{
+  void from_json(nlohmann::json const& j, age &a)
+  {
+    a.m_val = j.get<int>();
+  }
+
+  void from_json(nlohmann::json const& j, name &n)
+  {
+    n.m_val = j.get<std::string>();
+  }
+
+  void from_json(nlohmann::json const& j, person &p)
+  {
+    p.m_age = j["age"].get<age>();
+    p.m_name = j["name"].get<name>();
+  }
+
+  void from_json(nlohmann::json const &j, address &a)
+  {
+    a.m_val = j.get<std::string>();
+  }
+
+  void from_json(nlohmann::json const& j, contact &c)
+  {
+    c.m_person = j["person"].get<person>();
+    c.m_address = j["address"].get<address>();
+  }
+
+  void from_json(nlohmann::json const&j, contact_book &cb)
+  {
+    cb.m_book_name = j["name"].get<name>();
+    cb.m_contacts = j["contacts"].get<std::vector<contact>>();
   }
 }
 
@@ -114,17 +180,49 @@ TEST_CASE("basic usage", "[udt]")
 {
   using nlohmann::json;
 
+  // a bit narcissic maybe :) ?
+  const udt::age a{23};
+  const udt::name n{"theo"};
+  const udt::person sfinae_addict{a, n};
+  const udt::address addr{"Paris"};
+  const udt::contact cpp_programmer{sfinae_addict, addr};
+  const udt::contact_book book{{"C++"}, {cpp_programmer, cpp_programmer}};
+
   SECTION("conversion to json via free-functions")
   {
-    udt::age a{23};
-
-    CHECK(json{a} == json{23});
-
-    // a bit narcissic maybe :) ?
-    udt::name n{"theo"};
-    CHECK(json{n} == json{"theo"});
-
-    udt::person sfinae_addict{a, n};
+    CHECK(json{a} == json(23));
+    CHECK(json{n} == json("theo"));
     CHECK(json{sfinae_addict} == R"({"name":"theo", "age":23})"_json);
+    CHECK(json("Paris") == json{addr});
+    CHECK(json{cpp_programmer} ==
+          R"({"person" : {"age":23, "name":"theo"}, "address":"Paris"})"_json);
+
+    CHECK(
+        json{book} ==
+        R"({"name":"C++", "contacts" : [{"person" : {"age":23, "name":"theo"}, "address":"Paris"}, {"person" : {"age":23, "name":"theo"}, "address":"Paris"}]})"_json);
   }
-}
\ No newline at end of file
+
+  SECTION("conversion from json via free-functions")
+  {
+    const auto big_json =
+        R"({"name":"C++", "contacts" : [{"person" : {"age":23, "name":"theo"}, "address":"Paris"}, {"person" : {"age":23, "name":"theo"}, "address":"Paris"}]})"_json;
+    const auto parsed_book = big_json.get<udt::contact_book>();
+    const auto book_name = big_json["name"].get<udt::name>();
+    const auto contacts = big_json["contacts"].get<std::vector<udt::contact>>();
+    const auto contact_json = big_json["contacts"].at(0);
+    const auto contact = contact_json.get<udt::contact>();
+    const auto person = contact_json["person"].get<udt::person>();
+    const auto address = contact_json["address"].get<udt::address>();
+    const auto age = contact_json["person"]["age"].get<udt::age>();
+    const auto name = contact_json["person"]["name"].get<udt::name>();
+
+    CHECK(age == a);
+    CHECK(name == n);
+    CHECK(address == addr);
+    CHECK(person == sfinae_addict);
+    CHECK(contact == cpp_programmer);
+    CHECK(contacts == book.m_contacts);
+    CHECK(book_name == udt::name{"C++"});
+    CHECK(book == parsed_book);
+  }
+}