内部模型的自定义模型绑定器

Question

我有一个这样的模型：

public class MainModel
{
   public string Id {get;set;}
   public string Title {get;set;}
   public TimePicker TimePickerField {get;set;}
}

TimePicker是一个内部模型，如下所示：

public class TimePicker 
{
   public TimeSpan {get;set;}
   public AmPmEnum AmPm {get;set;}
}

我正在尝试为内部模型创建一个自定义的模型绑定：TimePicker

问题是:如何在自定义模型绑定器中获取以表单形式提交到TimePicker模型字段中的值？

如果我尝试像这样得到它：

var value = bindingContext.ValueProvider.GetValue(bindingContext.ModelName);

我只是在value中获得了null。

我不确定如何正确实现模型绑定器。

public class TimePickerModelBinder : DefaultModelBinder
{
    public override object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext)
    {
        if (bindingContext == null)
        {
            throw new ArgumentNullException("bindingContext");
        }
        var result = new TimePicker();

        var value = bindingContext.ValueProvider.GetValue(bindingContext.ModelName);
        if (value != null)
        {
            bindingContext.ModelState.SetModelValue(bindingContext.ModelName, value);
            try
            {
                //result = Duration.Parse(value.AttemptedValue);
            }
            catch (Exception ex)
            {
               bindingContext.ModelState.AddModelError(bindingContext.ModelName, ex.Message);
            }
        }    

        return result;
    }
}

Answer 1

下面的方法对我很有效。

型号：

public enum AmPmEnum
{
    Am, 
    Pm
}

public class TimePicker 
{
    public TimeSpan Time { get; set; }
    public AmPmEnum AmPm { get; set; }
}

public class MainModel
{
    public TimePicker TimePickerField { get; set; }
}

控制器：

public class HomeController : Controller
{
    public ActionResult Index()
    {
        var model = new MainModel
        {
            TimePickerField = new TimePicker
            {
                Time = TimeSpan.FromHours(1),
                AmPm = AmPmEnum.Pm
            }
        };
        return View(model);
    }

    [HttpPost]
    public ActionResult Index(MainModel model)
    {
        return View(model);
    }
}

视图(~/Views/Home/Index.cshtml)：

@model MainModel
@using (Html.BeginForm())
{
    @Html.EditorFor(x => x.TimePickerField)
    <button type="submit">OK</button>
}

自定义编辑器模板(~/Views/Shared/EditorTemplates/TimePicker.cshtml)，它将Time和AmPm属性合并到一个输入字段中，并且稍后将需要一个自定义模型绑定器，以便在提交表单时拆分它们：

@model TimePicker
@Html.TextBox("_picker_", string.Format("{0} {1}", Model.Time, Model.AmPm))

和模型绑定器：

public class TimePickerModelBinder : IModelBinder
{
    public object BindModel(
        ControllerContext controllerContext, 
        ModelBindingContext bindingContext
    )
    {
        var key = bindingContext.ModelName + "._picker_";
        var value = bindingContext.ValueProvider.GetValue(key);
        if (value == null)
        {
            return null;
        }

        var result = new TimePicker();

        try
        {
            // TODO: instead of hardcoding do your parsing
            // from value.AttemptedValue which will contain the string
            // that was entered by the user
            return new TimePicker
            {
                Time = TimeSpan.FromHours(2),
                AmPm = AmPmEnum.Pm
            };
        }
        catch (Exception ex)
        {
            bindingContext.ModelState.AddModelError(
                bindingContext.ModelName, 
                ex.Message
            );
            // This is important in order to preserve the original user
            // input in case of error when redisplaying the view
            bindingContext.ModelState.SetModelValue(key, value);
        }
        return result;
    }
}

最后在Application_Start中注册您的模型绑定器

ModelBinders.Binders.Add(typeof(TimePicker), new TimePickerModelBinder());