Using the CompareValidator control to compare user input date with today's date

Question

hey..i would like to compare the current date with the date entered by user..however, i'm encountering errors so far..

i tried something like this:

<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()" />

and i got an error stating that the value of DateTime.Today.ToShortDateString() of the ValueToCompare property of "" cannot be converted to type 'date' i also tried ValueToCompare="DateTime.Now.Date()" and i got the same error message.

please help me and i greatly appreciate it.

Solution 1

You're just using the ValueToCompare property as a literal string. You need to use ASP tags in it if you want to execute code to get a dynamic value. Try this:

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

Then in your Page_Load method, call Page.DataBind().

This will execute the databinder code when the page is loaded, and put the value in between the quotes.

Solution 2

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

In the page load event set the validator's value to compare as

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

Solution 3

We can set the ValueToCompare in code behind

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

for the compare validator:

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

Why not use Page.DataBind?

Consider the following scenario. I need to display the gridview only on the click of the Action button. The datasource is defined declaratively. But, if I use Page.DataBind() it will show the grid even on the page load.

 <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>

Code behind

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;
        }
    }
  }

Comments

[HelloBD]

this show me The value '' of the ValueToCompare property of 'Comparevalidator1' cannot be converted to type 'Date'.

[nuiun]

Sorry - I forgot to mention that you'll also need to call "Page.DataBind()" in your Page_Load method.

[comecme]

Just wondering, if this requires you to call DataBind() in the Page_Load, couldn't you just as well write MyCompareValidator.ValueToCompare = DateTime.Today.ToShortDateString(); in the Page_Load?

[Jean-François Beauchamp]

The CompareValidator requires Currency, Date, Double, Integer or String as Type. Check with Intellisense in Visual Studio. I am using VS2008 and Asp.Net 3.5.

[CallMeLaNN]

You miss the Operator="GreaterThan" otherwise it will treat as Equal

[LCJ]

@comecme I have posted an answer by setting ValueToCompare in code behind.

[ErTR]

Why do you have to use #? Is this a databinding operation?