JAVA高级面试进阶训练营视频教程

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1、通过对象接收请求数据时的null

必须为对象的属性设置get与set

private System.String _EMail = System.String.Empty;
        public System.String EMail
        {
            get {return _EMail;}
            set {_EMail = value;}
        }

　　

 

2、通过ajax传递的empty在对象中自动转换为null

第一个解决方案

[DisplayFormat(ConvertEmptyStringToNull = false)]
public string test{get;set;}

 

第二个解决方案

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

namespace AiAn.GPS.Web.Models
{
    //重写DataAnnotationsModelMetadataProvider方法中的CreateMetadata方法
    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 AiAn.GPS.Web.Models.MyDataAnnotationsModelMetadataProvider();