think\Model::hasManyThrough PHP Method

    public function hasManyThrough($model, $through, $foreignKey = '', $throughKey = '', $localKey = '', $alias = [])
    {
        // 记录当前关联信息
        $model = $this->parseModel($model);
        $through = $this->parseModel($through);
        $localKey = $localKey ?: $this->getPk();
        $foreignKey = $foreignKey ?: Loader::parseName($this->name) . '_id';
        $name = Loader::parseName(basename(str_replace('\\', '/', $through)));
        $throughKey = $throughKey ?: $name . '_id';
        return $this->relation()->hasManyThrough($model, $through, $foreignKey, $throughKey, $localKey, $alias);
    }