如何在.NET的MVC中执行Enum绑定到视图的模型？ [英] How do I perform an Enum binding to a view's model in .NET's MVC?

问题描述

如何将枚举绑定到MVC中的一个下拉列表中，使模型在发布后有效？
不确定它需要一个转换器或其他东西，我提供的代码，你推荐的解决方案是什么？
（以下代码导致ModelError）

How can I bind an enum into a drop down in MVC to make the model be valid after a post? Not sure does it need a converter or something else, I provide the code, what is your recommended solution? (the below code causes ModelError)

枚举：

public enum TimePlan
{   Routine = 0,
    Single = 1 }

模型：

 public TimePlan TheTimePlan { get; set; }

 public SelectListItem[] TimeList { get; set; }

控制器：

    [HttpPost]
    public virtual ActionResult Education(EducationViewModel EducationModelInfo)
    {
        if (ModelState.IsValid)
        { ...
    } }

查看绑定

@Html.DropDownListFor(m => m.CourseTimePlan, Model.TimeList, "Please select the time plan") 

推荐答案

您没有显示如何填充此TimeList集合。尝试这样，它应该工作：

You haven't shown how you populated this TimeList collection. Try like this and it should work:

public TimePlan TheTimePlan { get; set; }

public IEnumerable<SelectListItem> TimeList
{
    get
    {
        var enumType = typeof(TimePlan);
        var values = Enum.GetValues(enumType).Cast<TimePlan>();

        var converter = TypeDescriptor.GetConverter(enumType);

        return
            from value in values
            select new SelectListItem
            {
                Text = converter.ConvertToString(value),
                Value = value.ToString(),
            };
    }
}

或者让它更通用你可以写一个可重用的帮助器：

or to make it a little more generic you could write a reusable helper:

public static IHtmlString DropDownListForEnum<TModel, TEnum>(
    this HtmlHelper<TModel> htmlHelper, 
    Expression<Func<TModel, TEnum>> expression
)
{
    var metadata = ModelMetadata.FromLambdaExpression(expression, htmlHelper.ViewData);
    var enumType = GetNonNullableModelType(metadata);
    var values = Enum.GetValues(enumType).Cast<TEnum>();
    var converter = TypeDescriptor.GetConverter(enumType);

    var items =
        from value in values
        select new SelectListItem
        {
            Text = converter.ConvertToString(value), 
            Value = value.ToString(), 
            Selected = value.Equals(metadata.Model)
        };

    return htmlHelper.DropDownListFor(expression, items);
}

然后您的模型只能包含枚举值：

and then your model could only contain the Enum value:

public TimePlan TheTimePlan { get; set; }

，在你看来使用助手：

@Html.DropDownListForEnum(x => x.TheTimePlan)

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