Add Note serializers

This way we don't only need to use json.

lib/note.dart

@@ -4,14 +4,24 @@ typedef NoteUpdator(Note note);
 
 class Note implements Comparable {
   String id;
-  final DateTime createdAt;
-  final String body;
+  DateTime createdAt;
+  String body;
 
   Note({this.createdAt, this.body, this.id});
 
   factory Note.fromJson(Map<String, dynamic> json) {
+    String id;
+    if (json.containsKey("id")) {
+      var val = json["id"];
+      if (val.runtimeType == String) {
+        id = val;
+      } else {
+        id = val.toString();
+      }
+    }
+
     return new Note(
-      id: json['id'],
+      id: id,
       createdAt: DateTime.parse(json['createdAt']),
       body: json['body'],
     );

lib/serializers.dart

@@ -0,0 +1,60 @@
+import 'dart:convert';
+
+import 'package:yaml/yaml.dart';
+import 'package:journal/note.dart';
+
+abstract class NoteSerializer {
+  String encode(Note note);
+  Note decode(String str);
+}
+
+class JsonNoteSerializer implements NoteSerializer {
+  @override
+  Note decode(String str) {
+    final json = JsonDecoder().convert(str);
+    return new Note.fromJson(json);
+  }
+
+  @override
+  String encode(Note note) {
+    return JsonEncoder().convert(note.toJson());
+  }
+}
+
+class MarkdownYAMLSerializer implements NoteSerializer {
+  @override
+  Note decode(String str) {
+    if (str.startsWith("---\n")) {
+      var parts = str.split("---\n");
+
+      var yamlMap = loadYaml(parts[1]);
+      Map<String, dynamic> map = new Map<String, dynamic>();
+      yamlMap.forEach((key, value) {
+        map[key] = value;
+      });
+      map['body'] = parts[2].trimLeft();
+
+      return new Note.fromJson(map);
+    }
+
+    return new Note(body: str);
+  }
+
+  @override
+  String encode(Note note) {
+    const serparator = '---\n';
+    var str = "";
+    str += serparator;
+
+    var metadata = note.toJson();
+    metadata.remove('body');
+    metadata.forEach((key, value) {
+      str += key + ": " + value + "\n";
+    });
+    str += serparator;
+    str += '\n';
+    str += note.body;
+
+    return str;
+  }
+}

pubspec.lock

@@ -374,7 +374,7 @@ packages:
     source: hosted
     version: "1.0.7"
   yaml:
-    dependency: transitive
+    dependency: "direct main"
     description:
       name: yaml
       url: "https://pub.dartlang.org"

pubspec.yaml

@@ -9,7 +9,7 @@ dependencies:
   path: "^1.5.1"
   path_provider: "^0.4.0"
   uuid: "^1.0.0"
-
+  yaml: "^2.1.13"
 
 dev_dependencies:
   flutter_test:

test/serializers_test.dart

@@ -0,0 +1,29 @@
+import 'dart:io';
+
+import 'package:journal/note.dart';
+import 'package:journal/serializers.dart';
+
+import 'package:test/test.dart';
+
+main() {
+  group('Serializers', () {
+    var note =
+        Note(id: "2", body: "This is the body", createdAt: new DateTime.now());
+
+    test('JSON Serializer', () {
+      var jsonSerializer = new JsonNoteSerializer();
+      var str = jsonSerializer.encode(note);
+      var note2 = jsonSerializer.decode(str);
+
+      expect(note2, note);
+    });
+
+    test('Markdown Serializer', () {
+      var jsonSerializer = new MarkdownYAMLSerializer();
+      var str = jsonSerializer.encode(note);
+      var note2 = jsonSerializer.decode(str);
+
+      expect(note2, note);
+    });
+  });
+}