asp.net - 为什么将错误的值传递给我的服务器验证函数？

Question

在我的网络表单上，我有一个文本框，我想对它执行自定义验证：

<asp:TextBox ID="tbDate" runat="server"></asp:TextBox>
<asp:Button ID="btnSubmit" runat="server" Text="Submit" />
<asp:CustomValidator runat="server" ID="valDate" ControlToValidate="tbDate" onServerValidate="valDate_ServerValidate" ValidateEmptyText="true" ></asp:CustomValidator>

在我后面的代码中，我将日期 TextBox 的 Text in 设置为Page_Load，并且我有一个验证功能：

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
    tbDate.Text = DateTime.Today.ToShortDateString
End Sub

Protected Sub valDate_ServerValidate(source As Object, args As ServerValidateEventArgs)        
    Dim newDate As DateTime
    args.IsValid = DateTime.TryParse(args.Value, newDate)
End Sub

问题出在：如果我在文本框中输入一个值并单击提交按钮（或按 Enter），则验证函数不会收到我输入的值。相反， insidevalDate_ServerValidate被args.Value设置为在 Page_Load 中设置的文本框的初始值。这里发生了什么？

Answer 1

你总是覆盖值，所以改变

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
    tbDate.Text = DateTime.Today.ToShortDateString
End Sub

到

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
    If Not IsPostBack Then tbDate.Text = DateTime.Today.ToShortDateString
End Sub