investbrain/app/Traits/HasCompositePrimaryKey.php

<?php

declare(strict_types=1);

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);
    }
}