asp.net-mvc-4 - 如何使用三元运算符检查将输入字段的值绑定到控件

Question

我有一些输入控件，我试图通过检查无效的 null 来绑定值

<input id="LastKnownLatitudeDegree" name="VesselMissing.LastKnownLatitudeDegree" value="@Model.VesselMissing != null ? @Model.VesselMissing.LastKnownLatitudeDegree : ''" class="form-control" max="89" min="0" step="1" type="number" data-dec="0"><span>&#176;</span>

如果我在控件顶部使用空检查，则用户无法看到输入数据

@if (@Model.VesselMissing != null)
{
   <input id="LastKnownLatitudeDegree" name="VesselMissing.LastKnownLatitudeDegree" value="@Model.VesselMissing.LastKnownLatitudeDegree" class="form-control" max="89" min="0" step="1" type="number" data-dec="0"><span>&#176;</span>
}

我有一些像这样的控件，我需要绑定值字段。我尝试过的另一种方法正在起作用，但我想知道是否有可能按照第一条语句执行

这可行，但我有大约 20 个控件，所以我正在考虑让它按照第一个语句工作

@{
     string LastKnownLatitudeDegree = string.Empty;
     if(Model.VesselMissing !=null)
     {
         LastKnownLatitudeDegree = Model.VesselMissing.LastKnownLatitudeDegree;
     }
 }
     <input id="LastKnownLatitudeDegree" name="VesselMissing.LastKnownLatitudeDegree" value="@LastKnownLatitudeDegree  class="form-control" max="89" min="0" step="1" type="number" data-dec="0"><span>&#176;</span>

标签： asp.net-mvc-4

Answer 1

在这两种情况下，您都有语法错误。

<input id="LastKnownLatitudeDegree" name="VesselMissing.LastKnownLatitudeDegree"
    value="@(Model.VesselMissing != null ? Model.VesselMissing.LastKnownLatitudeDegree : "")" /> 

或者

@if (Model.VesselMissing != null)
{
   <input id="LastKnownLatitudeDegree" name="VesselMissing.LastKnownLatitudeDegree" value="@Model.VesselMissing.LastKnownLatitudeDegree" class="form-control" max="89" min="0" step="1" type="number" data-dec="0"><span>&#176;</span>
}