自定义模型绑定器不验证模型

Question

我开始玩knockout.js并且这样做我使用了FromJsonAttribute(由Steve Sanderson创建).我遇到了自定义属性未执行模型验证的问题.我把一个简单的例子放在一起 - 我知道它看起来像很多代码 - 但基本问题是如何强制在自定义模型绑定器中验证模型.

using System.ComponentModel.DataAnnotations;

namespace BindingExamples.Models
{
    public class Widget
    {
        [Required]
        public string Name { get; set; }
    }
}

这是我的控制器:

using System;
using System.Web.Mvc;
using BindingExamples.Models;

namespace BindingExamples.Controllers
{
    public class WidgetController : Controller
    {

        public ActionResult Index()
        {
            return View();
        }

        [HttpPost]
        public ActionResult Index(Widget w)
        {
            if(this.ModelState.IsValid)
            {
                TempData["message"] = String.Format("Thanks for inserting {0}", w.Name);
                return RedirectToAction("Confirmation");
            }
            return View(w);
        }

        [HttpPost]
        public ActionResult PostJson([koListEditor.FromJson] Widget w)
        {
            //the ModelState.IsValid even though the widget has an empty Name
            if (this.ModelState.IsValid)
            {
                TempData["message"] = String.Format("Thanks for inserting {0}", w.Name);
                return RedirectToAction("Confirmation");
            }
            return View(w);
        }

        public ActionResult Confirmation()
        {
            return View();
        }

    }
}

我的问题是该模型在我的PostJson方法中始终有效.为了完整性,这里是FromJson属性的Sanderson代码:

using System.Web.Mvc;
using System.Web.Script.Serialization;

namespace koListEditor
{
    public class FromJsonAttribute : CustomModelBinderAttribute
    {
        private readonly static JavaScriptSerializer serializer = new JavaScriptSerializer();

        public override IModelBinder GetBinder()
        {
            return new JsonModelBinder();
        }

        private class JsonModelBinder : IModelBinder
        {
            public object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext)
            {
                var stringified = controllerContext.HttpContext.Request[bindingContext.ModelName];
                if (string.IsNullOrEmpty(stringified))
                    return null;
                var model = serializer.Deserialize(stringified, bindingContext.ModelType);
                return model;
            }
        }
    }
}

Answer 1

描述

该FromJsonAttribute只结合模型和呢,像你说的,没有验证.

您可以向其添加验证FromJsonAttribute,以便根据其DataAnnotations属性验证模型.

这可以使用TypeDescriptor该类完成.

TypeDescriptor提供有关组件特征的信息,例如其属性,属性和事件.

看看我的解决方案.我测试了它.

解

private class JsonModelBinder : IModelBinder
{
    public object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext)
    {
        var stringified = controllerContext.HttpContext.Request[bindingContext.ModelName];
        if (string.IsNullOrEmpty(stringified))
            return null;
        var model = serializer.Deserialize(stringified, bindingContext.ModelType);

        // DataAnnotation Validation
        var validationResult = from prop in TypeDescriptor.GetProperties(model).Cast<PropertyDescriptor>()
                                from attribute in prop.Attributes.OfType<ValidationAttribute>()
                                where !attribute.IsValid(prop.GetValue(model))
                                select new { Propertie = prop.Name, ErrorMessage = attribute.FormatErrorMessage(string.Empty) };

        // Add the ValidationResult's to the ModelState
        foreach (var validationResultItem in validationResult)
            bindingContext.ModelState.AddModelError(validationResultItem.Propertie, validationResultItem.ErrorMessage);

        return model;
    }
}

更多信息

• TypeDescriptor类
• System.ComponentModel.DataAnnotations命名空间