add nova

nova/src/Fields/PreviewableFields.php

@@ -0,0 +1,60 @@
+<?php
+
+namespace Laravel\Nova\Fields;
+
+use Laravel\Nova\Http\Requests\NovaRequest;
+
+trait PreviewableFields
+{
+    /**
+     * Indicates whether to show the field in the modal preview.
+     *
+     * @var (callable(\Laravel\Nova\Http\Requests\NovaRequest):(bool))|bool
+     */
+    public $showOnPreview = false;
+
+    /**
+     * Show the field in the modal preview.
+     *
+     * @param  (callable(\Laravel\Nova\Http\Requests\NovaRequest):(bool))|bool  $callback
+     * @return $this
+     */
+    public function showOnPreview($callback = true)
+    {
+        $this->showOnPreview = $callback;
+
+        return $this;
+    }
+
+    /**
+     * Specify that the element should only be shown on the preview modal.
+     *
+     * @return $this
+     */
+    public function onlyOnPreview()
+    {
+        $this->showOnIndex = false;
+        $this->showOnDetail = false;
+        $this->showOnCreation = false;
+        $this->showOnUpdate = false;
+        $this->showOnPreview = true;
+
+        return $this;
+    }
+
+    /**
+     * Determine if the field is to be shown in the preview modal.
+     *
+     * @param  \Laravel\Nova\Http\Requests\NovaRequest  $request
+     * @param  mixed  $resource
+     * @return bool
+     */
+    public function isShownOnPreview(NovaRequest $request, $resource): bool
+    {
+        if (is_callable($this->showOnPreview)) {
+            $this->showOnPreview = call_user_func($this->showOnPreview, $request, $resource);
+        }
+
+        return $this->showOnPreview;
+    }
+}