Models: add autoFill method for asynchronous default value load

src/db/Model.ts

@@ -83,6 +83,13 @@ export default abstract class Model {
         }
     }
 
+    /**
+     * Override this to automatically fill obvious missing data i.e. from relation or default value that are fetched
+     * asynchronously.
+     */
+    public async autoFill(): Promise<void> {
+    }
+
     protected async beforeSave(exists: boolean, connection: Connection): Promise<void> {
     }
 
@@ -90,6 +97,7 @@ export default abstract class Model {
     }
 
     public async save(connection?: Connection, postHook?: (callback: () => Promise<void>) => void): Promise<void> {
+        await this.autoFill();
         await this.validate(false, connection);
 
         const exists = await this.exists();