Make it easy to cache new data

lib/helpers/database/database_contract.dart

@@ -8,10 +8,15 @@ class DatabaseContract {
   static const DATABASE_FILE_NAME = "database.sqlite";
 }
 
+/// Base table contract
+abstract class BaseTableContract {
+  static const C_ID = "id";
+}
+
 /// User table contract
 abstract class UserTableContract {
   static const TABLE_NAME = "users";
-  static const C_ID = "id";
+  static const C_ID = BaseTableContract.C_ID;
   static const C_FIRST_NAME = "first_name";
   static const C_LAST_NAME = "last_name";
   static const C_VISIBILITY  = "visibility";

lib/helpers/database/model_database_helper.dart

@@ -0,0 +1,72 @@
+import 'package:comunic/helpers/database/database_contract.dart';
+import 'package:comunic/helpers/database/database_helper.dart';
+import 'package:comunic/models/cache_model.dart';
+
+/// Model database helper
+///
+/// Base model for caching data in the database
+///
+/// @author Pierre HUBERT
+
+abstract class ModelDatabaseHelper<T extends CacheModel> {
+
+  /// Get the name of the target table. Must be specified by the children
+  /// of this class
+  String tableName();
+
+  /// Initialize an element from a map
+  T initializeFromMap(Map<String, dynamic> map);
+
+  /// Insert an entry in the database
+  Future<void> _insertDB(T el) async {
+    await (await DatabaseHelper.get())
+        .insert(tableName(), el.toMap());
+  }
+
+  /// Update an element in the database
+  Future<void> _updateDB(T el) async {
+    await (await DatabaseHelper.get()).update(
+      tableName(),
+      el.toMap(),
+      where: "${BaseTableContract.C_ID} = ?",
+      whereArgs: [el.id],
+    );
+  }
+
+  /// Get an element from the database with a specified [id]
+  ///
+  /// Returns null if none found
+  Future<T> get(int id) async {
+    List<Map> maps = await (await DatabaseHelper.get()).query(
+      UserTableContract.TABLE_NAME,
+      where: '${UserTableContract.C_ID} = ?',
+      whereArgs: [id],
+    );
+
+    if (maps.length > 0) return initializeFromMap(maps[0]);
+
+    return null;
+  }
+
+  /// Check out whether an element specified with its [id] is present
+  /// or not in the local database
+  Future<bool> has(int id) async {
+    return (await get(id)) != null;
+  }
+
+  /// Insert or update information about a el (depends of the presence
+  /// of previous element information in the database
+  Future<void> insertOrUpdate(T el) async {
+    if (await has(el.id))
+      await _updateDB(el);
+    else
+      await _insertDB(el);
+  }
+
+  /// Insert or update an important amount of elements
+  Future<void> insertOrUpdateAll(List<T> list) async {
+    for(int i = 0; i < list.length; i++)
+      await insertOrUpdate(list[i]);
+  }
+
+}

lib/helpers/database/users_database_helper.dart

@@ -1,62 +1,24 @@
+import 'package:comunic/helpers/database/model_database_helper.dart';
 import 'package:comunic/models/user.dart';
 
 import 'database_contract.dart';
-import 'database_helper.dart';
 
 /// User database helper
 ///
 /// @author Pierre HUBERT
 
-class UsersDatabaseHelper {
-  /// Insert a user in the database
-  Future<void> _insertDB(User user) async {
-    await (await DatabaseHelper.get())
-        .insert(UserTableContract.TABLE_NAME, user.toMap());
+class UsersDatabaseHelper extends ModelDatabaseHelper<User> {
+
+
+  @override
+  String tableName() {
+    return UserTableContract.TABLE_NAME;
   }
 
-  /// Update a user in the database
-  Future<void> _updateDB(User user) async {
-    await (await DatabaseHelper.get()).update(
-      UserTableContract.TABLE_NAME,
-      user.toMap(),
-      where: "${UserTableContract.C_ID} = ?",
-      whereArgs: [user.id],
-    );
+  @override
+  User initializeFromMap(Map<String, dynamic> map) {
+    return User.fromMap(map);
   }
 
-  /// Get a user from the database with a specified [id]
-  ///
-  /// Returns null if none found
-  Future<User> get(int id) async {
-    List<Map> maps = await (await DatabaseHelper.get()).query(
-      UserTableContract.TABLE_NAME,
-      where: '${UserTableContract.C_ID} = ?',
-      whereArgs: [id],
-    );
 
-    if (maps.length > 0) return User.fromMap(maps[0]);
-
-    return null;
-  }
-
-  /// Check out whether a user information specified with its [id] is present
-  /// or not in the local database
-  Future<bool> has(int id) async {
-    return (await get(id)) != null;
-  }
-
-  /// Insert or update information about a user (depends of the presence
-  /// of previous user information in the database
-  Future<void> insertOrUpdate(User user) async {
-    if (await has(user.id))
-      await _updateDB(user);
-    else
-      await _insertDB(user);
-  }
-
-  /// Insert or update an important amount of user information
-  Future<void> insertOrUpdateAll(List<User> list) async {
-    for(int i = 0; i < list.length; i++)
-      await insertOrUpdate(list[i]);
-  }
 }