diff --git a/native_class.mustache b/native_class.mustache
index 3a6c457..b1c8c5b 100644
--- a/native_class.mustache
+++ b/native_class.mustache
@@ -32,7 +32,7 @@ class {{{classname}}} {
       {{/required}}
     {{/isNullable}}
   {{/isEnum}}
-  {{{datatypeWithEnum}}}{{#isNullable}}?{{/isNullable}}{{^isNullable}}{{^required}}{{^defaultValue}}?{{/defaultValue}}{{/required}}{{/isNullable}} {{{name}}};
+  {{#isNullable}}Option<{{/isNullable}}{{{datatypeWithEnum}}}{{#isNullable}}>?{{/isNullable}}{{^isNullable}}{{^required}}{{^defaultValue}}?{{/defaultValue}}{{/required}}{{/isNullable}} {{{name}}};
 
 {{/vars}}
   @override
@@ -55,7 +55,7 @@ class {{{classname}}} {
     final json = <String, dynamic>{};
   {{#vars}}
     {{#isNullable}}
-    if (this.{{{name}}} != null) {
+    if (this.{{{name}}}?.isSome ?? false) {
     {{/isNullable}}
     {{^isNullable}}
       {{^required}}
@@ -67,38 +67,40 @@ class {{{classname}}} {
     {{#isDateTime}}
       {{#pattern}}
       json[r'{{{baseName}}}'] = _isEpochMarker(r'{{{pattern}}}')
-        ? this.{{{name}}}{{#isNullable}}!{{/isNullable}}{{^isNullable}}{{^required}}{{^defaultValue}}!{{/defaultValue}}{{/required}}{{/isNullable}}.millisecondsSinceEpoch
-        : this.{{{name}}}{{#isNullable}}!{{/isNullable}}{{^isNullable}}{{^required}}{{^defaultValue}}!{{/defaultValue}}{{/required}}{{/isNullable}}.toUtc().toIso8601String();
+        ? this.{{{name}}}{{#isNullable}}!.unwrap(){{/isNullable}}{{^isNullable}}{{^required}}{{^defaultValue}}!{{/defaultValue}}{{/required}}{{/isNullable}}.millisecondsSinceEpoch
+        : this.{{{name}}}{{#isNullable}}!.unwrap(){{/isNullable}}{{^isNullable}}{{^required}}{{^defaultValue}}!{{/defaultValue}}{{/required}}{{/isNullable}}.toUtc().toIso8601String();
       {{/pattern}}
       {{^pattern}}
-      json[r'{{{baseName}}}'] = this.{{{name}}}{{#isNullable}}!{{/isNullable}}{{^isNullable}}{{^required}}{{^defaultValue}}!{{/defaultValue}}{{/required}}{{/isNullable}}.toUtc().toIso8601String();
+      json[r'{{{baseName}}}'] = this.{{{name}}}{{#isNullable}}!.unwrap(){{/isNullable}}{{^isNullable}}{{^required}}{{^defaultValue}}!{{/defaultValue}}{{/required}}{{/isNullable}}.toUtc().toIso8601String();
       {{/pattern}}
     {{/isDateTime}}
     {{#isDate}}
       {{#pattern}}
       json[r'{{{baseName}}}'] = _isEpochMarker(r'{{{pattern}}}')
-        ? this.{{{name}}}{{#isNullable}}!{{/isNullable}}{{^isNullable}}{{^required}}{{^defaultValue}}!{{/defaultValue}}{{/required}}{{/isNullable}}.millisecondsSinceEpoch
-        : _dateFormatter.format(this.{{{name}}}{{#isNullable}}!{{/isNullable}}{{^isNullable}}{{^required}}{{^defaultValue}}!{{/defaultValue}}{{/required}}{{/isNullable}}.toUtc());
+        ? this.{{{name}}}{{#isNullable}}!.unwrap(){{/isNullable}}{{^isNullable}}{{^required}}{{^defaultValue}}!{{/defaultValue}}{{/required}}{{/isNullable}}.millisecondsSinceEpoch
+        : _dateFormatter.format(this.{{{name}}}{{#isNullable}}!.unwrap(){{/isNullable}}{{^isNullable}}{{^required}}{{^defaultValue}}!{{/defaultValue}}{{/required}}{{/isNullable}}.toUtc());
       {{/pattern}}
       {{^pattern}}
-      json[r'{{{baseName}}}'] = _dateFormatter.format(this.{{{name}}}{{#isNullable}}!{{/isNullable}}{{^isNullable}}{{^required}}{{^defaultValue}}!{{/defaultValue}}{{/required}}{{/isNullable}}.toUtc());
+      json[r'{{{baseName}}}'] = _dateFormatter.format(this.{{{name}}}{{#isNullable}}!.unwrap(){{/isNullable}}{{^isNullable}}{{^required}}{{^defaultValue}}!{{/defaultValue}}{{/required}}{{/isNullable}}.toUtc());
       {{/pattern}}
     {{/isDate}}
     {{^isDateTime}}
       {{^isDate}}
-      json[r'{{{baseName}}}'] = this.{{{name}}}{{#isArray}}{{#uniqueItems}}{{#isNullable}}!{{/isNullable}}.toList(growable: false){{/uniqueItems}}{{/isArray}};
+      json[r'{{{baseName}}}'] = this.{{{name}}}{{#isArray}}{{#uniqueItems}}{{#isNullable}}!.unwrap(){{/isNullable}}.toList(growable: false){{/uniqueItems}}{{/isArray}};
       {{/isDate}}
     {{/isDateTime}}
     {{#isNullable}}
     } else {
-      json[r'{{{baseName}}}'] = null;
+      if(this.{{{name}}}?.isNone ?? false) {
+        json[r'{{{baseName}}}'] = null;
+      }
     }
     {{/isNullable}}
     {{^isNullable}}
       {{^required}}
         {{^defaultValue}}
     } else {
-      json[r'{{{baseName}}}'] = null;
+    //  json[r'{{{baseName}}}'] = null;
     }
         {{/defaultValue}}
       {{/required}}
@@ -111,27 +113,17 @@ class {{{classname}}} {
   /// [value] if it's a [Map], null otherwise.
   // ignore: prefer_constructors_over_static_methods
   static {{{classname}}}? fromJson(dynamic value) {
+    upgradeDto(value, "{{{classname}}}");
     if (value is Map) {
       final json = value.cast<String, dynamic>();
 
-      // Ensure that the map contains the required keys.
-      // Note 1: the values aren't checked for validity beyond being non-null.
-      // Note 2: this code is stripped in release mode!
-      assert(() {
-        requiredKeys.forEach((key) {
-          assert(json.containsKey(key), 'Required key "{{{classname}}}[$key]" is missing from JSON.');
-          assert(json[key] != null, 'Required key "{{{classname}}}[$key]" has a null value in JSON.');
-        });
-        return true;
-      }());
-
       return {{{classname}}}(
   {{#vars}}
     {{#isDateTime}}
-        {{{name}}}: mapDateTime(json, r'{{{baseName}}}', r'{{{pattern}}}'){{#required}}{{^isNullable}}!{{/isNullable}}{{/required}}{{^required}}{{#defaultValue}} ?? {{{.}}}{{/defaultValue}}{{/required}},
+        {{{name}}}:  {{#isNullable}}Some.tryFrom({{/isNullable}}mapDateTime(json, r'{{{baseName}}}', r'{{{pattern}}}'){{#required}}{{^isNullable}}!{{/isNullable}}{{/required}}{{^required}}{{#defaultValue}} ?? {{{.}}}{{/defaultValue}}{{/required}}{{#isNullable}}){{/isNullable}},
     {{/isDateTime}}
     {{#isDate}}
-        {{{name}}}: mapDateTime(json, r'{{{baseName}}}', r'{{{pattern}}}'){{#required}}{{^isNullable}}!{{/isNullable}}{{/required}}{{^required}}{{#defaultValue}} ?? {{{.}}}{{/defaultValue}}{{/required}},
+        {{{name}}}: {{#isNullable}}Some.tryFrom({{/isNullable}}mapDateTime(json, r'{{{baseName}}}', r'{{{pattern}}}'){{#required}}{{^isNullable}}!{{/isNullable}}{{/required}}{{^required}}{{#defaultValue}} ?? {{{.}}}{{/defaultValue}}{{/required}}{{#isNullable}}){{/isNullable}},
     {{/isDate}}
     {{^isDateTime}}
       {{^isDate}}
@@ -189,7 +181,7 @@ class {{{classname}}} {
         {{{name}}}: null, // No support for decoding binary content from JSON
               {{/isBinary}}
               {{^isBinary}}
-        {{{name}}}: {{{complexType}}}.fromJson(json[r'{{{baseName}}}']){{#required}}{{^isNullable}}!{{/isNullable}}{{/required}}{{^required}}{{#defaultValue}} ?? {{{.}}}{{/defaultValue}}{{/required}},
+        {{{name}}}: {{#isNullable}}Some.tryFrom({{/isNullable}}{{{complexType}}}.fromJson(json[r'{{{baseName}}}']){{#required}}{{^isNullable}}!{{/isNullable}}{{/required}}{{^required}}{{#defaultValue}} ?? {{{.}}}{{/defaultValue}}{{/required}}{{#isNullable}}){{/isNullable}},
               {{/isBinary}}
             {{/isMap}}
           {{/isArray}}
@@ -211,18 +203,23 @@ class {{{classname}}} {
             {{/isMap}}
             {{^isMap}}
               {{#isNumber}}
-        {{{name}}}: {{#isNullable}}json[r'{{{baseName}}}'] == null
+        {{{name}}}: {{#isNullable}}Some.tryFrom(json[r'{{{baseName}}}'] == null
             ? {{#defaultValue}}{{{.}}}{{/defaultValue}}{{^defaultValue}}null{{/defaultValue}}
-            : {{/isNullable}}{{{datatypeWithEnum}}}.parse('${json[r'{{{baseName}}}']}'),
+            : {{/isNullable}}{{{datatypeWithEnum}}}.parse('${json[r'{{{baseName}}}']}'){{#isNullable}}){{/isNullable}},
               {{/isNumber}}
+              {{#isDouble}}
+        {{{name}}}: {{#isNullable}}Some.tryFrom({{/isNullable}}(mapValueOfType<num>(json, r'{{{baseName}}}'){{#required}}{{^isNullable}}!{{/isNullable}}{{/required}}{{^required}}{{#defaultValue}} ?? {{{.}}}{{/defaultValue}}{{/required}}).toDouble(){{#isNullable}}){{/isNullable}},
+              {{/isDouble}}
+              {{^isDouble}}
               {{^isNumber}}
                 {{^isEnum}}
-        {{{name}}}: mapValueOfType<{{{datatypeWithEnum}}}>(json, r'{{{baseName}}}'){{#required}}{{^isNullable}}!{{/isNullable}}{{/required}}{{^required}}{{#defaultValue}} ?? {{{.}}}{{/defaultValue}}{{/required}},
+        {{{name}}}: {{#isNullable}}Some.tryFrom({{/isNullable}}mapValueOfType<{{{datatypeWithEnum}}}>(json, r'{{{baseName}}}'){{#required}}{{^isNullable}}!{{/isNullable}}{{/required}}{{^required}}{{#defaultValue}} ?? {{{.}}}{{/defaultValue}}{{/required}}{{#isNullable}}){{/isNullable}},
                 {{/isEnum}}
                 {{#isEnum}}
-        {{{name}}}: {{{enumName}}}.fromJson(json[r'{{{baseName}}}']){{#required}}{{^isNullable}}!{{/isNullable}}{{/required}}{{^required}}{{#defaultValue}} ?? {{{.}}}{{/defaultValue}}{{/required}},
+        {{{name}}}: {{#isNullable}}Some.tryFrom({{/isNullable}}{{{enumName}}}.fromJson(json[r'{{{baseName}}}']){{#required}}{{^isNullable}}!{{/isNullable}}{{/required}}{{^required}}{{#defaultValue}} ?? {{{.}}}{{/defaultValue}}{{/required}}{{#isNullable}}){{/isNullable}},
                 {{/isEnum}}
               {{/isNumber}}
+              {{/isDouble}}
             {{/isMap}}
           {{/isArray}}
         {{/complexType}}