在类别模型中，可以定义两个关系 belongsToMany 带属性和属性组

Class Category extends eloquent
{

    public function attributes()
    {
        return $this->belongsToMany(Attribute::class, 'Categories_Additional_Attributes', 'category_id');
    }

    public function attribute_groups()
    {
        return $this->belongsToMany(AttributeGroups::class, 'Categories_Attribute_Groups', 'category_id');
    }
}

现在你可以把它们当作

Category::with(['attributes', 'attribute_groups'])->get();

对于双向Map，可以将其定义为

Class Attribute extends eloquent
{

    public function categories()
    {
        return $this->belongsToMany(Category::class, 'Categories_Additional_Attributes', 'attribute_id');
    }
}

Class AttributeGroups extends eloquent
{

    public function categories()
    {
        return $this->belongsToMany(Category::class, 'Categories_Attribute_Groups', 'attribute_group_id');
    }
}