在 asp.net 中的 onfocus__doPostBack 之后保持焦点答案

【问题标题】：Maintain Focus after onfocus__doPostBack in asp.net在 asp.net 中的 onfocus__doPostBack 之后保持焦点
【发布时间】：2013-02-07 19:28:49
【问题描述】：

当用户点击文本框时，我必须执行服务器端事件。到目前为止，我可以使用 onfocus 事件来管理调用 javascript 函数，但是如果我尝试删除 onfocus，执行一些代码，将焦点放回控件上，然后它会在无限循环中再次触发 onfocus 事件。下面的示例...

HTML

<asp:TextBox ID="TextBox1" runat="server" AutoPostBack="True" onfocus="CallServer(this);"></asp:TextBox>
<asp:TextBox ID="TextBox2" runat="server" AutoPostBack="True" onfocus="CallServer(this);"></asp:TextBox>

Javascript

function CallServer(obj) {
  if (obj != "") {
    var control = document.getElementById(obj.id)
    __doPostBack(obj.id, "onfocus");
  }
}

代码隐藏

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

   If IsPostBack Then
      Dim target As String = Page.Request.Params.Get("__EVENTTARGET")
      Dim eventarg As String = Page.Request.Params.Get("__EVENTARGUMENT")
      Dim PostControl As Control = Nothing

      If target <> "" Then
         PostControl = Page.FindControl(target)
      End If

      If eventarg = "onfocus" Then
         CType(PostControl, TextBox).Attributes("onfocus") = "null"

         ...do some code

         Page.SetFocus(PostControl)

         CType(ctrl, TextBox).Attributes.Add("onfocus", "CallServer(this)")
      End If
   End If

End Sub

【问题讨论】：

标签： javascript asp.net vb.net visual-studio-2010

【解决方案1】：

您可以通过使用 Page_PreRender 中的 ScriptManager.SetFocus 来完成此操作。本例中的 ScriptManager 位于 MasterPage 中。

Private Sub Page_PreRender(sender As Object, e As System.EventArgs) Handles Me.PreRender

    If HiddenFieldPostBackControl.Value <> "" Then
        Dim PostBackControl As Control = FindControlById(HiddenFieldPostBackControl.Value)
        If PostBackControl IsNot Nothing Then
            Dim sm As ScriptManager = ScriptManager.GetCurrent(Master.Page)
            sm.SetFocus(PostBackControl )
        End If
    End If

End Sub

注意：如果您正在使用动态控件（必须在每次回发时重新创建），则必须在将事件添加到其他控件时删除目标控件的 (OnFocus of OnFocusIn) 事件。这必须在 Page_PreRender 之前完成。

function ControlOnFocus(ctrl, request, doc, min, max, docSec) {
        if (ctrl != "") {
            var hf = document.getElementById("MainContent_HiddenFieldPostControl").value = ctrl.id;
            var c = document.getElementById(ctrl.id);
            PostControl = ctrl;

            //ONFOCUS
            if (request.toLowerCase() == 'server') {
                //SERVER Handler
                __doPostBack(ctrl.id, "onfocus");
            } else {
                //CLIENT Handler
                //Your code here...
            }

            ReAssignEvent(ctrl.id);

            var hf = document.getElementById("MainContent_hfValidated");
            hf.innerText = "";
        };
    };
 function ReAssignEvent(ControlID) {
        //loop through an array with (id,onfocus event) for each control
        //this array is only required for the focus event

        for (var i = 0; i < FocusArray.length; i++) {

            var carr = FocusArray[i].split("[1]"); //split the element to get id and event
            var carrId = carr[0]; //get the id
            var c = document.getElementById(carrId); //find control and assign control to var
            var e = carr[1]; //assing event as string to var

            if (c != null) {
                if (ControlID!= carrId) {
                    if (c.type == "text" || c.type == "select-one") {
                        c.setAttribute("onfocus", e);
                    } else {
                        c.setAttribute("onfocusin", e);
                    }
                } else {
                    if (c.type == "text" || c.type == "select-one") {
                        c.removeAttribute("onfocus");
                    } else {
                        c.removeAttribute("onfocusin");
                    }
                }
            }

        }
 }

【讨论】：