網站在Visual Studio中工作，但不在服務器上

Question

網站在Visual Studio中工作，但在服務器上斷開。獲取錯誤：「System.NullReferenceException：未將對象引用設置爲對象的實例。」 我已經重新發布了該項目，並且仍然出錯。我從服務器上拉下文件，它仍然在我的機器上，但不在服務器上。會發生什麼？

<div class="main"> 
<h2 class="queue_title">Queue</h2> 
@if (Model.Count > 0) 
{ 

<table class="inputTableLeft"> 
    <tr><th>Company</th><th>Category</th><th>Assigned Resource</th></tr> 
    <tr> 
     <td> 
      <select id="CompanySelect"> 
       <option value="0">All</option> 
       @foreach (var company in Model.GroupBy(r => r.Company)) 
       { 
        <option value="@company.First().Company">@company.First().Company</option> 
       } 
      </select> 
     </td> 
     <td> 
      <select id="CategorySelect"> 
       <option value="0">All</option> 
       @foreach (var category in Model.GroupBy(r => r.Category)) 
       { 
        <option value="@category.Key.Id">@category.Key.Name</option> 
       } 
      </select> 
     </td> 
     <td> 
      <select id="AssignedResource"> 
       <option value="0">All</option> 
       @foreach (var resource in Model.GroupBy(r => r.AssignedUserName)) 
<!--Breaking here:-->{ 
         <option value="@resource.First().AssignedADUser.FullName">@resource.First().AssignedADUser.FullName</option> 
        } 
      </select> 
     </td> 
    </tr> 
</table> 
<table class="inputTableRight"> 
    <tr> 
     <th>Incident/Ticket Number</th><th>RCA Number</th> 
    </tr> 
    <tr> 
     <td> 
      <input type="text" id="IncidentNumFilter" /> 
     </td> 
     <td> 
      <input type="text" id="RCANumFilter" /> 
     </td> 
    </tr> 
</table> 
<table id="QueueTable"> 
    <tr> 
    @foreach (var grp in Model.GroupBy(r => r.StatusId)) 
    { 
     <th> 
      @grp.First().Status.Name 
     </th> 
    } 
    </tr> 
    <tr> 
    @foreach (var grp in Model.GroupBy(r => r.StatusId)) 
    { 
     <td data-status="@grp.First().StatusId"> 
     @foreach (RCAModel rca in grp.OrderBy(r => r.CreateTime).OrderByDescending(r => r.Critical)) 
     { 
      <div data-rca="@rca.Id" data-company="@rca.Company" data-assigned="@rca.AssignedADUser.FullName" data-category="@rca.Category.Id" data-incident="@rca.TicketNumber" class="line @(rca.Critical ? "highlight_red" : "")"> 
       <a href="@Url.Action("EditRCA", new { id = rca.Id })" > 
        @rca.Id : Created - @rca.CreateTime @(rca.Critical ? Html.Label("expression", " - CRITICAL") : Html.Label("", "")) 
       </a> 
      </div> 

     } 
     </td> 
    }  
    </tr> 
</table> 
} 
else 
{ 
    @: No RCAs in queue 
} 
</div> 

Answer 1

你可能會在這條產業鏈從某處得到一個空值：

@resource.First().AssignedADUser.FullName 

添加一些記錄和一些空的檢查解決此代碼，以弄清楚什麼是零。

例如：這裏需要

var firstRes = resource.First(); 
if (firstRes != null) 
{ 
    var user = firstRes.AssignedADUser 
    if (user != null) 
    { 
     // Do your normal work. 
    } 
    else 
    { 
     // Log a message here 
    } 
} 
else 
{ 
    // Log a message here 
}