使用 CompareValidator 控件将用户输入日期与今天的日期进行比较

Question

嘿..我想将当前日期与用户输入的日期进行比较..但是，到目前为止我遇到了错误..

我试过这样的：

<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()" />

我收到一条错误消息，指出“”的ValueToCompare 属性的DateTime.Today.ToShortDateString() 的值无法转换为“日期”类型 我也试过ValueToCompare="DateTime.Now.Date()"，我得到了同样的错误信息。

请帮助我，我非常感激。

Answer 1

您只是将ValueToCompare 属性用作文字字符串。如果要执行代码以获取动态值，则需要在其中使用 ASP 标签。试试这个：

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

然后在您的Page_Load 方法中，调用Page.DataBind()。

这将在页面加载时执行数据绑定器代码，并将值放在引号之间。

Answer 2

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

在页面加载事件中设置要比较的验证器的值

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

Answer 3

我们可以在后面的代码中设置ValueToCompare

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

对于比较验证器：

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

为什么不使用 Page.DataBind？

考虑以下场景。我需要仅在单击“操作”按钮时显示网格视图。数据源以声明方式定义。但是，如果我使用 Page.DataBind() 它会在页面加载时显示网格。

 <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>

后面的代码

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;
        }
    }
  }

Answer 4

试试这个。

<asp:RequiredFieldValidator ID="RequiredFieldValidator3" runat="server" ErrorMessage="Date is required" ControlToValidate="txtmDate"></asp:RequiredFieldValidator>

<asp:RegularExpressionValidator ID="RegularExpressionValidator1" runat="server" ErrorMessage="Date is not valid (MM.DD.YYYY)" ControlToValidate="txtDate" ValidationExpression="(0[1-9]|1[012])[- /.](0[1-9]|[12][0-9]|3[01])[- /.](19|20)\d\d" ></asp:RegularExpressionValidator>

用户输入日期（日期格式）的方式也很重要。在这里，我使用了 MM.DD.YYYY 日期格式。

<asp:CompareValidator ID="CompareValidatorGreaterThanToday" runat="server" ErrorMessage="The date must be greater than today" ControlToValidate="txtDate" Type="date" Operator="GreaterThan" ValueToCompare="<%# DateTime.Today.ToShortDateString() %>" ></asp:CompareValidator>

然后在您的 Page_Load 方法 (*.aspx.cs) 中，调用 Page.DataBind()。

例子：

protected void Page_Load(object sender, EventArgs e)
{            
   Page.DataBind();
}

Answer 5

试试下面写的：

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