GridView里 ButtonField 两次提交的一个Bug .

 

class Data
    {
        public string D { get; set; }
        public string A { get; set; }
    }
    public partial class WebForm1 : System.Web.UI.Page
    {
        static int i = 0;
        protected void Page_Load(object sender, EventArgs e)
        {
            i++;
            Response.Write(i);

            if (IsPostBack == false)
            {
                bind();
            }

        }

        private void bind()
        {
            this.gv.AutoGenerateColumns = false;
            this.gv.Columns.Clear();
            List<Data> dat = new List<Data>();
            dat.Add(new Data() { D = "ddd" });

            this.gv.Columns.Add(new BoundField() { DataField = "D" });

            this.gv.Columns.Add(new ButtonField() { ButtonType = ButtonType.Image, ImageUrl = "warningIcon.png",CommandName="Delete" });

            this.gv.DataSource = dat;
            this.gv.DataBind();

            (this.gv.Rows[0].Cells[1].Controls[0] as ImageButton).Attributes["onclick"] = "alert('ok');";

        }

        protected void gcon_SelectedIndexChanged(object sender, EventArgs e)
        {

        }

        protected void Button1_Click(object sender, EventArgs e)
        {

        }

        protected void gv_RowDeleting(object sender, GridViewDeleteEventArgs e)
        {
            Response.Write("(" + i.ToString() + ")");
        }

 

前台GridView 只要绑定 onrowdeleting="gv_RowDeleting" 即可.

两次提交的原因是:

    ImageButton 生成了标签 <input type="image"   onclick="javascript:__doPostBack('gv','Delete$0')" />

    input type="Image" 本身会 Post 一次, 而 __doPostBack 也会提交一次. 造成两次提交.

根本解决,是弃用 ButtonField中的Image 绑定 .换用 LinkButton , 在 Page_Load 里增加:

            (this.gv.Rows[0].Cells[1].Controls[0] as LinkButton).Controls.Add(
                new HtmlImage() { Src = "warningIcon.png" });

或用正则表达式,在 __doPostBack 后 添加 ;return false ; 只能在控件内部实现, 不能在页面上全局实现.页面的 Render 里实现会影响Ajax .

重写 GridView 的 RenderContents 方法:

        protected override void RenderContents(HtmlTextWriter writer)
        {
            //base.RenderContents(writer);
            StringWriter stringWriter = new StringWriter();
            HtmlTextWriter htmlWriter = new HtmlTextWriter(stringWriter);
            base.RenderContents(htmlWriter);
            string html = stringWriter.ToString();

            string[] eachOne = Regex.Split(
                    html,
                    @"(?<=<[a-z]*\s+.*[a-z]*=""[^""]*__doPostBack\s*\(\s*'[^""]*""(?=\s))"
                    , RegexOptions.IgnoreCase | RegexOptions.Singleline
                    );

            for (int i = 0; i < eachOne.Length - 1; i++)
            {
                eachOne[i] = eachOne[i].Insert(eachOne[i].Length - 1, ";return false;");
            }

            html=  string.Join("", eachOne);

            writer.Write(html);
        }

       protected override void RenderContents(HtmlTextWriter writer)
        {
            //base.RenderContents(writer);
            StringWriter stringWriter = new StringWriter();
            HtmlTextWriter htmlWriter = new HtmlTextWriter(stringWriter);
            base.RenderContents(htmlWriter);
            string html = stringWriter.ToString();

            string[] eachOne = Regex.Split(
                    html,
                    @"(?<=<[a-z]*\s+.*[a-z]*=""[^""]*__doPostBack\s*\(\s*'[^""]*""(?=\s))"
                    , RegexOptions.IgnoreCase | RegexOptions.Singleline
                    );

            for (int i = 0; i < eachOne.Length - 1; i++)
            {
                eachOne[i] = eachOne[i].Insert(eachOne[i].Length - 1, ";return false;");
            }

            html=  string.Join("", eachOne);

            writer.Write(html);
        }