Update property values using the ViewModel

November 9, 2022

The ViewModel below is used on multiple forms.

My goal is to update values received from those forms using the DateRangeViewModel itself. Is it possible?

Example: User submits "2022-01-01 12:00:00 AM" and I update it to "2022-01-02 12:00:00 AM" before passing it to the controller.

What I have tried:

public class DateRangeViewModel
{
    public DateTime? From { get; set; }
    public DateTime? To { 
        get 
        {
            if (!To.HasValue) { return null; }
            return To.Value.AddDays(1);
        }
        set {}
    }
}

And it throws an Exception of type ‘System.StackOverflowException’.

I know I can update these values through the controller. However, it is not my intent.

>Solution :

Use a backing field:

public class DateRangeViewModel
{   
    public DateTime? From { get; set; }
    public DateTime? To { 
        get 
        {
            return _to;
        }
        set
        {
            if (value == null)
            {
                _to = null;
            }
            else
            {
                _to = value.Value.AddDays(1);
            }
        }
    }

    private DateTime? _to;
}

Probably it would be clearer, if you use an additional Property:

public class DateRangeViewModel
{   
    public DateTime? From { get; set; }
    public DateTime? To { get; set; }
    public DateTime? ToPlus1Day => To == null ? null : To.Value.AddDays(1)
}