mvc5模型绑定不适用于dropdownlistfor

Question

I have a view model class:

public class TankDurationViewModel
    {        
        public int selectedTankFactor { get;set; }
        public List<SelectListItem> tank_factor_list { get; set; }

        public double? myAnswer { get; set; }

        public TankDurationViewModel()
        {
            this.tank_factor_list = new List<SelectListItem>();
            this.tank_factor_list.Add(new SelectListItem { Text = "E", Value = "0.28" });
            this.tank_factor_list.Add(new SelectListItem { Text = "H", Value = "3.14" });
        }
    }

View:

@Html.DropDownListFor(x=>x.selectedTankFactor,Model.tank_factor_list,"Tank Type") 

When I submit, my selectedTankFactor will not bind. I will always be 0. When i look at the formcollection, the selection is in the formcollection. If I change the int selectedTankFactor into string, it will bind correctly but this it not what I want. Does this relate to how i initialize the SelectListItem? How do i get it to bind int? The SelectListItem only take string for value. Also how do i force user to choose a selection other than "Tank Type" before submitting?

Answer 1

Make selectedTankFactor to a decimal and if you don't want the user to submit form without selecting tank type, add required validation to selectedTankFactor property. You also have to include jquery validate library for client side validations .

[Required]
public decimal selectedTankFactor { get;set; }