add composite key trait

app/Traits/HasCompositePrimaryKey.php

@@ -0,0 +1,53 @@
+<?php
+
+namespace App\Traits; 
+
+trait HasCompositePrimaryKey
+{
+    /**
+     * Get the value indicating whether the IDs are incrementing.
+     *
+     * @return bool
+     */
+    public function getIncrementing()
+    {
+        return false;
+    }
+
+    /**
+     * Set the keys for a save update query.
+     *
+     * @param  \Illuminate\Database\Eloquent\Builder $query
+     * @return \Illuminate\Database\Eloquent\Builder
+     */
+    protected function setKeysForSaveQuery($query)
+    {
+        foreach ($this->getKeyName() as $key) {
+            // UPDATE: Added isset() per devflow's comment.
+            if (isset($this->$key))
+                $query->where($key, '=', $this->$key);
+            else
+                throw new \Exception(__METHOD__ . 'Missing part of the primary key: ' . $key);
+        }
+
+        return $query;
+    }
+
+    // UPDATE: From jessedp. See his edit, below.
+    /**
+     * Execute a query for a single record by ID.
+     *
+     * @param  array  $ids Array of keys, like [column => value].
+     * @param  array  $columns
+     * @return mixed|static
+     */
+    public static function find($ids, $columns = ['*'])
+    {
+        $me = new self;
+        $query = $me->newQuery();
+        foreach ($me->getKeyName() as $key) {
+            $query->where($key, '=', $ids[$key]);
+        }
+        return $query->first($columns);
+    }
+}