How do I render a group of checkboxes using MVC 4 and View Models (strongly typed)

Question

I\'m rather new to the ASP.net MVC world and I\'m trying to figure out how to render a group of checkboxes that are strongly typed to a view model. In webforms I would just use

Answer 1

Use a string array in your view model. You can then use the helper I hacked together. if you don't want to use the helper and the enum then see the actual Html at the bottom. The binder will return a string array with only the selected string values in it. if none are selected it returns a null value for your array. You must account for that, you have been warned :)

View Model:

[Display(Name = "Which Credit Cards are Accepted:")]
        public string[] CreditCards { get; set; }

Helper:

public static HtmlString CheckboxGroup(this HtmlHelper htmlHelper, Expression> propertySelector, Type EnumType)
        {
            var groupName = GetPropertyName(propertySelector);
            var modelValues = ModelMetadata.FromLambdaExpression(propertySelector, htmlHelper.ViewData).Model;//propertySelector.Compile().Invoke(htmlHelper.ViewData.Model);
        StringBuilder literal = new StringBuilder();  

        foreach (var value in Enum.GetValues(EnumType))
        {
            var svalue = value.ToString();
            var builder = new TagBuilder("input");
            builder.GenerateId(groupName);
            builder.Attributes.Add("type", "checkbox");
            builder.Attributes.Add("name", groupName);
            builder.Attributes.Add("value", svalue);
            var contextValues = HttpContext.Current.Request.Form.GetValues(groupName);
            if ((contextValues != null && contextValues.Contains(svalue)) || (modelValues != null && modelValues.ToString().Contains(svalue)))
            {
                builder.Attributes.Add("checked", null);
            }

            literal.Append(String.Format("
{1} {0}", svalue.Replace('_', ' '),builder.ToString(TagRenderMode.Normal)));
        }

        return (HtmlString)htmlHelper.Raw(literal.ToString()); 
    }

    private static string GetPropertyName(Expression> propertySelector)
    {
        var body = propertySelector.Body.ToString();
        var firstIndex = body.IndexOf('.') + 1;
        return body.Substring(firstIndex);
    }

HTML:

@Html.CheckboxGroup(m => m.CreditCards, typeof(VendorCertification.Enums.CreditCardTypes))

Use this if helper extensions scare you:

            
             Visa


            
             MasterCard