C# Get child property from the item of Parent Collection

Question

I am using ASP.NET MVC. I have a parent:

public class ReportFilterBuilderStruct
{
    public string PropName { get; set; }
    public string ClassName { get; set; }
    public string SubListName { get; set; }
    //public virtual string SecondaryPropName { get; set; }

    public ReportFilterBuilderStruct(string inpPropName, string inpClassName, string inpSubListName)
    {
        PropName = inpPropName;
        ClassName = inpClassName;
        SubListName = inpSubListName;
    }
}

And a child:

public class DateReportFilterBuilderStruct : ReportFilterBuilderStruct
{
    public string SecondaryPropName { get; set; }

    public DateReportFilterBuilderStruct(string inpPropName, string inpSecondaryPropName, string inpClassName, string inpSubListName) : base(inpPropName, inpClassName, inpSubListName)
    {
        SecondaryPropName = inpSecondaryPropName;
    }
}

}

It will be used in my view to store some data about my model class property. editorListProp will store both ReportFilterBuilderStruct and DateReportFilterBuilderStruct , that is why it is a List of parent class objects.

var editorListProp = new List<NTStock.Models.ReportFilterBuilderStruct>();

Now i want to access them:

if (subItem.GetType() == typeof(NTStock.Models.ReportFilterBuilderStruct))
{
    <div class="row align-items-center">
        @Html.DisplayName(subItem.PropName)
    </div>
    <div class="row align-items-center  mb-2">
        @Html.Editor(subItem.PropName, "", new { htmlAttributes = new { @class = subItem.ClassName } })
    </div>
}
else
{
    <div class="row align-items-center">
        @Html.DisplayName(subItem.PropName)
    </div>
    <div class="row align-items-center mb-2">
        <div class="col-6">
            From:
            @Html.Editor(subItem.PropName, "", new { htmlAttributes = new { @class = subItem.ClassName } })
        </div>
        <div class="col-6">
            Till:
            @Html.Editor(subItem.SecondaryPropName, "", new { htmlAttributes = new { @class = subItem.ClassName } })
        </div>
    </div>
}

So the point is, that I can't access my SecondaryPropName , even though I made sure that current subItem is definetly of type DateReportFilterBuilderStruct .

Answer 1

您必须将subItem为DateReportFilterBuilderStruct ，例如：

((DateReportFilterBuilderStruct)subItem).SecondaryPropName

Answer 2

This approach would work in a dynamically typed language like Python, but not in C#. Your list is of type List<ReportFilterBuilderStruct> . When you access an item from the list, eg list[0] , you get back an object of type ReportFilterBuilderStruct , even if you stored a DateReportFilterBuilderStruct there and GetType() correctly returns DateReportFilterBuilderStruct .

In the else branch you will first have to cast the item to DateReportFilterBuilderStruct :

else
{
    @{ var dateReport = (DateReportFilterBuilderStruct)subItem; }
    <div class="row align-items-center">
        @Html.DisplayName(dateReport.PropName)
    </div>
    <div class="row align-items-center mb-2">
        <div class="col-6">
            From:
            @Html.Editor(dateReport.PropName, "", new { htmlAttributes = new { @class = dateReport.ClassName } })
        </div>
        <div class="col-6">
            Till:
            @Html.Editor(dateReport.SecondaryPropName, "", new { htmlAttributes = new { @class = dateReport.ClassName } })
        </div>
    </div>
}