add nova

nova/src/Fields/FormatsRelatableDisplayValues.php

@@ -0,0 +1,53 @@
+<?php
+
+namespace Laravel\Nova\Fields;
+
+use Closure;
+use Laravel\Nova\Nova;
+use Laravel\Nova\Resource;
+
+trait FormatsRelatableDisplayValues
+{
+    /**
+     * The column that should be displayed for the field.
+     *
+     * @var (callable(mixed):(string))|null
+     */
+    public $display;
+
+    /**
+     * Format the associatable display value.
+     *
+     * @param  mixed  $resource
+     * @return string
+     */
+    protected function formatDisplayValue($resource)
+    {
+        if (! $resource instanceof Resource) {
+            $resource = Nova::newResourceFromModel($resource);
+        }
+
+        if (is_callable($this->display)) {
+            return call_user_func($this->display, $resource);
+        }
+
+        return $resource->title();
+    }
+
+    /**
+     * Set the column that should be displayed for the field.
+     *
+     * @param  (\Closure(mixed):(string))|string  $display
+     * @return $this
+     */
+    public function display($display)
+    {
+        $this->display = $display instanceof Closure
+                        ? $display
+                        : function ($resource) use ($display) {
+                            return $resource->{$display};
+                        };
+
+        return $this;
+    }
+}