Implemented saving data as JSON object to a file.

lib/server/titamaapi.dart

@@ -3,6 +3,7 @@ library titama.server;
 import 'package:rpc/rpc.dart';
 
 import '../common/messages.dart';
+import './titamaio.dart';
 
 @ApiClass(version: 'v1')
 class TitamaApi {
@@ -56,6 +57,9 @@ class TitamaApi {
   @ApiMethod(method: 'DELETE', path: 'course/{id}')
   List<Course> deleteCourse(int id) {
     _courses.removeWhere((course) => course.id == id);
+
+    new TitamaIo().writeJson(_courses);
+
     return _courses;
   }
 
@@ -64,6 +68,8 @@ class TitamaApi {
     newCourse.id = _courses.length;
     _courses.add(newCourse);
 
+    new TitamaIo().writeJson(_courses);
+
     return newCourse;
   }
 
@@ -72,6 +78,9 @@ class TitamaApi {
     course.id = id;
     int index =  _courses.indexOf(_courses.singleWhere((crs) => crs.id == id));
     _courses.replaceRange(index, index + 1, [course]);
+
+    new TitamaIo().writeJson(_courses);
+
     return course;
   }
 }

lib/server/titamaio.dart

@@ -0,0 +1,24 @@
+library titama.io;
+
+import 'dart:io';
+import 'dart:convert';
+
+import '../common/messages.dart';
+
+/**
+ * Class for writing and loading the courses as JSON to a file.
+ */
+class TitamaIo {
+
+  final _filename = "./data.json";
+
+  /**
+   * Write courses as JSON in a file.k
+   * @param List<Courses> _course List of courses to save.
+   */
+  writeJson(List<Course> _courses) async {
+    String _json = JSON.encode(_courses);
+    await new File(_filename).writeAsString(_json);
+  }
+
+}