implement abstracts

lib/DatabaseModel.ts

@@ -24,8 +24,13 @@ export abstract class DatabaseModel {
     this.id = id;
   }
 
-  public abstract get(key: string): string|number|boolean;
-  public abstract set(key: string, value: string|number|boolean): void;
+  public get (key: string): string|number|boolean {
+    return this.data[key];
+  }
+
+  public set (key: string, value: string|number|boolean): void {
+    this.data[key] = value;
+  }
 
   public abstract async read(): Promise<void>;
   public abstract async write(): Promise<void>;