[增添]添加了datasource的setting数据库以及默认值

vendor/spatie/laravel-settings/src/SettingsCasts/SettingsCast.php

@@ -0,0 +1,18 @@
+<?php
+
+namespace Spatie\LaravelSettings\SettingsCasts;
+
+interface SettingsCast
+{
+    /**
+     * Will be used to when retrieving a value from the repository, and
+     * inserting it into the settings class.
+     */
+    public function get($payload);
+
+    /**
+     * Will be used to when retrieving a value from the settings class, and
+     * inserting it into the repository.
+     */
+    public function set($payload);
+}