asp.net-mvc – ASP MVC – 多对多的关系

在包含多对多关系的EF(代码优先)模型的asp mvc中,如何将该关系绑定到复选框,然后将这些更改优雅地传播到我的数据库.

如果视图仅返回已检查的复选框的值,则我不再知道先前检查过哪些值.我是否再次拉回原始物体然后比较两者？它感觉很脏,可能是因为我已经习惯让EF魔法管理对象上已经改变的属性.

我已经有了一个我不满意的脏版本.

[HttpPost]
    public ActionResult Edit(int id,FormCollection collection)
    {
        try
        {
            // TODO: Add insert logic here
            Program p = _programRep.GetByID(id);

            //manually update properties
            //change to model binding later


            EditPolicies(ref p,collection["SelectedPolicies"].ToString().Split(','));

            _programRep.Save(p);

            return RedirectToAction("Index");
        }
        catch
        {
            return View();
        }
    }

    private void EditPolicies(ref Program c,string[] selectedvals)
    {
        //I could do comparison logic here 
        int count = c.Policies.Count;
        for (int i = 0; i < count; i++)
        {
            c.Policies.Remove(c.Policies.ElementAt(0));
        }

        for (int i = 0; i < selectedvals.Count(); i++)
        {
            Policy g = _policyRep.GetByID(int.Parse(selectedvals[i]));
            c.Policies.Add(g);
        }
    }