當使用郵政郵件MVC 4剃鬚刀移動視圖引擎生成錯誤

Question

我正在使用郵政發送訂單確認。這是一個MVC4項目。該代碼正確地發送電子郵件確認。

最近，我添加了MVC移動到這個項目。一切正常 - 除非在用戶使用移動設備時發送確認電子郵件。這是爲了確認類：

public class OrderConfirmation : Postal.Email 
    { 
     public string email { get; set; } 
     public string partyid { get; set; } 
     public string GrouponCode { get; set; } 
     public string originalpartyDate { get; set; } 
     public string originalpartyStartTime { get; set; } 
     public string originalpartyTitle { get; set; } 
     public string originalOrderDate { get; set; } 
     public bool GrouponWasUpgraded { get; set; } 
     public decimal GrouponFaceValue { get; set; } 
     public bool ClassCancelled { get; set; } 
     public string firstname { get; set; } 
     public string orderlink { get; set; } 
    } 

然後它被調用是這樣的：

ci = new Email.OrderConfirmation 
{ 
    ClassCancelled = false, 
    email = Email, 
    firstname = FirstName, 
    orderlink = "https://website.com/Checkout/Archive?orderlinkid=" + OrderLinkId, 
    originalpartyDate = DateStart.ToShortDateString(), 
    originalpartyStartTime = DateStart.ToShortTimeString(), 
    originalpartyTitle = odt.Party.Title, 
    partyid = odt.PartyId.ToString() 
}; 
Task task = ci.SendAsync(); 

在我的Global.asax.cs文件我發現移動設備，然後將顯示模式，如這樣的：

protected void Application_Start() 
    { 
    DisplayModeProvider.Instance.Modes.Insert(0, new 
     DefaultDisplayMode("Tablet") 
     { 
      ContextCondition = (ctx => 
      ctx.Request.UserAgent.IndexOf("iPad", StringComparison.OrdinalIgnoreCase) >= 0 || 
      ctx.Request.UserAgent.IndexOf("Android", StringComparison.OrdinalIgnoreCase) >= 0 && 
      ctx.Request.UserAgent.IndexOf("mobile", StringComparison.OrdinalIgnoreCase) < 1) 
     }); 
     DisplayModeProvider.Instance.Modes.Insert(1, new DefaultDisplayMode("iPhone") 
      { 
       ContextCondition = (ctx => 
        ctx.GetOverriddenBrowser().IsMobileDevice || 
        ctx.GetOverriddenUserAgent().IndexOf 
        ("iPhone", StringComparison.OrdinalIgnoreCase) >= 0 
        ) 
      }); 
    /// omitted the rest of the (standard) code for brevity 
    } 

該錯誤消息我得到的是一個通用的「不設置到對象的實例對象引用」 我已經把堆棧跟蹤，以及錯誤代碼生成時的圖像。

iisexpress.exe Error: 0 : 4/15/2014 11:09:33 AMSystem.NullReferenceException: Object reference not set to an instance of an object. 
    at application.MvcApplication.<Application_Start>b__1(HttpContextBase ctx) in c:\Dropbox\SourceCode\PUYF_NonTFS\PUYF_Website\Application\Global.asax.cs:line 132 
    at System.Web.WebPages.DefaultDisplayMode.CanHandleContext(HttpContextBase httpContext) 
    at System.Web.WebPages.DisplayModeProvider.<>c__DisplayClass6.<GetAvailableDisplayModesForContext>b__5(IDisplayMode mode) 
    at System.Linq.Enumerable.WhereListIterator`1.MoveNext() 
    at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection) 
    at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source) 
    at System.Web.Mvc.VirtualPathProviderViewEngine.GetPath(ControllerContext controllerContext, String[] locations, String[] areaLocations, String locationsPropertyName, String name, String controllerName, String cacheKeyPrefix, Boolean useCache, String[]& searchedLocations) 
    at System.Web.Mvc.VirtualPathProviderViewEngine.FindView(ControllerContext controllerContext, String viewName, String masterName, Boolean useCache) 
    at System.Web.Mvc.ViewEngineCollection.<>c__DisplayClassc.<FindView>b__a(IViewEngine e) 
    at System.Web.Mvc.ViewEngineCollection.Find(Func`2 lookup, Boolean trackSearchedPaths) 
    at System.Web.Mvc.ViewEngineCollection.FindView(ControllerContext controllerContext, String viewName, String masterName) 
    at Postal.EmailViewRenderer.CreateView(String viewName, ControllerContext controllerContext) 
    at Postal.EmailViewRenderer.Render(Email email, String viewName) 
    at Postal.EmailService.CreateMailMessage(Email email) 
    at Postal.EmailService.SendAsync(Email email) 
    at Postal.Email.SendAsync() 
    at Application.Models.Order.SendConfirmation(ArtStoreEntities dbcontext) in  
c:\Dropbox\SourceCode\PUYF_NonTFS\PUYF_Website\Application\Models\Order.cs:line 134 

看來，當郵政正在生成視圖，它擊中在Global.asax文件中的Application_Start，因爲用戶代理屬性爲null - 它產生的誤差。我試着在application_start過程中的特定代碼周圍放置一個try catch塊 - 但這不起作用。

我需要幫助如何告訴MVC或郵政不要打擾displaymodes。有什麼建議麼？

Answer 1

這是我落得這樣做：

DisplayModeProvider.Instance.Modes.Insert(0, new 
      DefaultDisplayMode("Tablet"){ 
     ContextCondition = (ctx => 
     ctx.Request.UserAgent != null && 
     (
     ctx.Request.UserAgent.IndexOf("iPad", StringComparison.OrdinalIgnoreCase) >= 0 || 
     ctx.Request.UserAgent.IndexOf("Android", StringComparison.OrdinalIgnoreCase) >= 0 && 
     ctx.Request.UserAgent.IndexOf("mobile", StringComparison.OrdinalIgnoreCase) < 1)) 
    }); 

    DisplayModeProvider.Instance.Modes.Insert(1, new DefaultDisplayMode("iPhone"){ 
     ContextCondition = (ctx => 
      ctx.Request.UserAgent != null && 
     (
      ctx.GetOverriddenBrowser().IsMobileDevice || 
      ctx.GetOverriddenUserAgent().IndexOf 
      ("iPhone", StringComparison.OrdinalIgnoreCase) >= 0 
      ) 
     ) 
    }); 

Answer 2

當ctx.Request.UserAgent爲空時，您可以嘗試使ContextCondition返回false嗎？