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我正在为我的网站创建一个简单的私人消息系统。这是模型：

public class PrivateMessage : GlobalViewModel
{
    [Key]
    public int MessageId { get; set; }

    public bool IsRead { get; set; }
    public DateTime CreatedDate { get; set; }
    [MaxLength(100)]
    public string Subject { get; set; }

    [MaxLength(2500)]
    public string Body { get; set; }

    public virtual UserProfile Sender { get; set; }

    public virtual UserProfile Receiver { get; set; }
}

如果您有任何新消息，我想检查每个页面请求，以便通知用户。因此，我制作了一个基本视图模型，其中包含：

public class GlobalViewModel
{
    [NotMapped]
    public virtual int NewMessages { get; set; }
}

所有其他视图模型都继承自此类。为了获取用户的新私人消息的数量，我这样做：

    public override void OnActionExecuted(ActionExecutedContext filterContext)
    {
        DBContext db = new DBContext();
        int userID = (int)Membership.GetUser().ProviderUserKey;
        int newMessages = db.PrivateMessages.Where(a => a.Receiver.UserId == userID && a.IsRead == false).Count();
        base.OnActionExecuted(filterContext);
    }

我来到这里，每个动作都确实调用了 OnActionExecuting。但我的问题是：

如何将 newMessages 添加到 GlobalViewModel？

我最终想要做的是在“主”视图中调用它

 You have @Model.NewMessages new messages
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1 回答 1

3

您可以覆盖OnActionExecuted在您的操作完成运行后运行的事件，这将允许您检查传递给视图的模型并可能通过在其上设置一些属性来修改它：

public class PrivateMessageFilterAttribute : ActionFilterAttribute
{
    public override void OnActionExecuting(ActionExecutedContext filterContext)
    {
        GlobalViewModel model = null;

        var viewResult = filterContext.Result as ViewResultBase;
        if (viewResult != null)
        {
            // The action returned a ViewResult or PartialViewResult
            // so we could attempt to read the model that was passed
            model = viewResult.Model as GlobalViewModel;
        }

        if (model == null)
        {
            var jsonResult = filterContext.Result as JsonResult;
            if (jsonResult != null)
            {
                // The action returned a JsonResult
                // so we could attempt to read the model that was passed
                model = jsonResult.Data as GlobalViewModel;
            }
        }

        if (model != null)
        {
            // We've managed to read the model 
            // Now we can set its NewMessages property
            model.NewMessages = GetNewMessages();
        }
    }

    private int GetNewMessages()
    {
        int userId = (int)Membership.GetUser().ProviderUserKey;
        int newMessages = db.PrivateMessages.Where(a => a.Receiver.UserId == userId && a.IsRead == false).Count();
    }
}

作为使用基本视图模型的替代方法，您可以编写一个自定义 HTML 帮助程序，该帮助程序将返回此信息。

于 2012-12-02T15:31:24.860 回答