.net mvc 解决接收空字符串自动转为null的问题的处理

.net mvc 解决接收空字符串自动转为null的问题的处理

.net mvc中用AJAX请求后台方法时，空字符传会自动转为null

解决方案：重写DataAnnotationsModelMetadataProvider方法中的CreateMetadata方法

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Linq;
using System.Web.Mvc;

namespace Web
{
    public class MyDataAnnotationsModelMetadataProvider : DataAnnotationsModelMetadataProvider
    {
        protected override ModelMetadata CreateMetadata(IEnumerable<Attribute> attributes, Type containerType, Func<object> modelAccessor, Type modelType, string propertyName)
        {
            var md = base.CreateMetadata(attributes, containerType, modelAccessor, modelType, propertyName);

            DataTypeAttribute dataTypeAttribute = attributes.OfType<DataTypeAttribute>().FirstOrDefault();
            DisplayFormatAttribute displayFormatAttribute = attributes.OfType<DisplayFormatAttribute>().FirstOrDefault();
            if (displayFormatAttribute == null && dataTypeAttribute != null)
            {
                displayFormatAttribute = dataTypeAttribute.DisplayFormat;
            }
            if (displayFormatAttribute == null)
            {
                md.ConvertEmptyStringToNull = false;
            }

            return md;
        }
    }
}

//在Global.asax的Application_Start方法中，重新覆盖原有对象
ModelMetadataProviders.Current = new MyDataAnnotationsModelMetadataProvider();