使用CompareValidator控件比較用戶輸入的日期與今天的日期

Question

hey..i想比較當前日期與user..however輸入的日期，我遇到錯誤爲止..

我嘗試是這樣的：

<asp:TextBox id="txtDate1" runat="server" />  
<asp:CompareValidator runat="server" ErrorMessage="The date must be greater than today" 
    ControlToValidate="txtDate1" type="date" 
    ValuetoCompare="DateTime.Today.ToShortDateString()" /> 

，我得到了一個錯誤，指出的「的」 ValueToCompare屬性DateTime.Today.ToShortDateString()值不能轉換爲類型「日期」 我也嘗試ValueToCompare="DateTime.Now.Date()"和我有同樣的錯誤信息。

請幫助我，我非常感激。

Answer 1

您只是使用ValueToCompare屬性作爲文字字符串。如果要執行代碼以獲取動態值，則需要在其中使用ASP標記。試試這個：

<asp:comparevalidator runat="server" 
    errormessage="The date must be greater than today" 
    controltovalidate="txtDate1" type="date" 
    valuetocompare="<%# DateTime.Today.ToShortDateString() %>" /> 

然後在您的Page_Load方法，調用Page.DataBind()。

這將在頁面加載時執行數據綁定代碼，並將值放在引號之間。

Answer 2

嘗試下面寫着：

<asp:CompareValidator runat="server" ErrorMessage="The date must be greater than today" 
ControlToValidate="txtDate1" type="DateTime" 
ValuetoCompare='<%# DateTime.Now.ToString("d") '%> /> 

Answer 3

<asp:CompareValidator ID="CompareValidator3" runat="server" 
         ControlToValidate="TextBox1" ErrorMessage="Date should be on or after today" 
         Operator="GreaterThanEqual" Type="Date"> 
</asp:CompareValidator> 

在頁面加載事件中設置驗證器的值進行比較的

CompareValidator3.ValueToCompare = DateTime.Now.ToShortDateString(); 

Answer 4

我們可以設置ValueToCompare在後面的代碼

 if (!Page.IsPostBack) 
     { 
      string currentDate = DateTime.Today.ToShortDateString(); 
      Comparevalidator1.ValueToCompare = currentDate; 
     } 

fo R上的比較驗證：

<asp:CompareValidator ID="Comparevalidator1" runat="server" ErrorMessage="The date must be greater than today" 
    Operator="GreaterThan" ControlToValidate="txtDate1" Type="date" Display="Dynamic" /> 

爲什麼不使用的Page.DataBind？

請考慮以下情況。我只需要點擊Action按鈕就可以顯示gridview。數據源是以聲明的方式定義的。但是，如果我使用Page.DataBind（），它甚至會在頁面加載時顯示網格。

<form id="form1" runat="server"> 
<asp:TextBox ID="txtDate1" CssClass="firstBox" runat="server" Text=""></asp:TextBox> 
<asp:CompareValidator ID="Comparevalidator1" runat="server" ErrorMessage="The date must be greater than today" 
    Operator="GreaterThan" ControlToValidate="txtDate1" Type="date" Display="Dynamic" /> 
<asp:Button ID="btnAction" class="submitButton" runat="server" Text="Action" OnClick="btnAction_Click" /> 
<asp:Button ID="btnDummy" class="submitButton" runat="server" Text="Dummy" OnClick="btnDummy_Click" /> 
<br /> 
<br /> 

<asp:GridView ID="GridView1" runat="server" DataSource="<%# EmployeesResult %>"> 
</asp:GridView> 
</form> 

代碼背後

public partial class ThirdTest : System.Web.UI.Page 
{ 
    protected void Page_Load(object sender, EventArgs e) 
    { 
     //Page.DataBind(); 

     if (!Page.IsPostBack) 
     { 
      string currentDate = DateTime.Today.ToShortDateString(); 
      txtDate1.Text = currentDate; 
      Comparevalidator1.ValueToCompare = currentDate; 
     } 
    } 

    protected void btnAction_Click(object sender, EventArgs e) 
    { 
     GridView1.DataBind(); 
     string value = GridView1.DataSource.ToString(); 
    } 

    protected void btnDummy_Click(object sender, EventArgs e) 
    { 

    } 

    //Propertry 
    public List<Employee> EmployeesResult 
    { 
     get 
     { 
      List<Employee> employees = new List<Employee>(); 
      employees.Add(new Employee { EmpID = 1, EmpName = "Emp1" }); 
      employees.Add(new Employee { EmpID = 2, EmpName = "Emp2" }); 
      return employees; 
     } 
    } 
    }