add nova

nova/src/Fields/Peekable.php

@@ -0,0 +1,89 @@
+<?php
+
+namespace Laravel\Nova\Fields;
+
+use Laravel\Nova\Http\Requests\NovaRequest;
+
+trait Peekable
+{
+    /**
+     * Indicates if the related resource can be peeked at.
+     *
+     * @var (callable(\Laravel\Nova\Http\Requests\NovaRequest):(bool))|bool|null
+     */
+    public $peekable = true;
+
+    /**
+     * Specify if the related resource can be peeked at.
+     *
+     * @param  (callable(\Laravel\Nova\Http\Requests\NovaRequest):(bool))|bool  $callback
+     * @return $this
+     */
+    public function peekable($callback = true)
+    {
+        $this->peekable = $callback;
+
+        return $this;
+    }
+
+    /**
+     * Prevent the user from peeking at the related resource.
+     *
+     * @return $this
+     */
+    public function noPeeking()
+    {
+        $this->peekable = false;
+
+        return $this;
+    }
+
+    /**
+     * Resolve whether the relation is able to be peeked at.
+     *
+     * @param  \Laravel\Nova\Http\Requests\NovaRequest  $request
+     * @return mixed
+     */
+    public function isPeekable(NovaRequest $request)
+    {
+        if (is_callable($this->peekable)) {
+            $this->peekable = call_user_func($this->peekable, $request);
+        }
+
+        return $this->peekable;
+    }
+
+    /**
+     * Determine if the relation has fields that can be peeked at.
+     *
+     * @param  \Laravel\Nova\Http\Requests\NovaRequest  $request
+     * @return bool
+     */
+    public function hasFieldsToPeekAt(NovaRequest $request)
+    {
+        if (! $request->isPresentationRequest() && ! $request->isResourcePreviewRequest()) {
+            return false;
+        }
+
+        if (is_null($relatedResource = $this->relatedResource())) {
+            return false;
+        }
+
+        return $relatedResource->peekableFieldsCount($request) > 0;
+    }
+
+    /**
+     * Return the appropriate related Resource for the field.
+     *
+     * @return \Laravel\Nova\Resource|null
+     */
+    protected function relatedResource()
+    {
+        if ($this instanceof MorphTo) {
+            return $this->morphToResource;
+        }
+
+        /** @phpstan-ignore-next-line */
+        return $this->belongsToResource;
+    }
+}