Q:

Format timespan as TotalMilliseconds

I am writing a simple ASP.Net page, where I have several fields, one of them is for timeout.  I want to display it as milliseconds (but still want to have a timespan instead of int/string).  I am writing following code:
<input asp-for="Entry. Interval" asp-format="{0:fff}" type="text" class="form-control"> 

But here is a problem.  This format is not working as expected.  I expect TimeSpan. FromMinutes(2).ToString("fff") to return 120000, but it returns 000.  It's obviosly becuase TimeSpan uses Milliseconds property, which is zero in this example, but I need TotalMilliseconds.  
Is there some format which force to show entire TimeSpan in desired units?  I really don't want to write an integer field and map it manually on this TimeSpan. 

A:

You could define another property only to be used in binding
class Entry
{
    public TimeSpan Interval { get; set; }
    public int IntervalMS
    {
        get { return (int)Interval. TotalMilliseconds; }
        set { Interval = TimeSpan. FromMilliseconds(value); }
    }
    //other stuff...
}

And then
<input asp-for="Entry. IntervalMs" type="text" class="form-control"> 

