在asp.net中的onfocus_doPostBack之后保持焦点

Maintain Focus after onfocus__doPostBack in asp.net

本文关键字：之后焦点 doPostBack asp net 中的 onfocus 更新时间：2023-09-26

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事件调用javascript函数，但如果我尝试删除onfocus，执行一些代码，将焦点放回控件上，那么它会在无限循环中再次触发onfocus活动。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");
  }
}

编码背后

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

您可以通过使用Page_PreRender中的ScriptManager.SetFocus来实现这一点。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：如果使用的是动态控件（每次回发时都必须重新创建），则必须删除目标控件的（OnFocusIn的OnFocus）事件，同时将该事件添加到其他控件。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");
                    }
                }
            }
        }
 }