[Solved] ASP.Net Error: Page.IsValid cannot be called before validation has taken place

Hi ihechi,

You need to call Page.IsValid method before the Page.IsValid property to force validation manually.

Refer below sample.

HTML

<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" runat="Server">
    <div class="form">
        <asp:UpdatePanel ID="UpdatePanelSub" runat="server">
            <ContentTemplate>
                <asp:TextBox ID="txtUserID" runat="server" AutoPostBack="true" OnTextChanged="txtUserID_TextChanged"  />
                <asp:RegularExpressionValidator ID="RegularExpressionValidator1" runat="server"
                    ControlToValidate="txtUserID" SetFocusOnError="true" Display="Dynamic"
                    ErrorMessage="Format is wrong, must be in the format of [A-Z]MMDDYYYY" ValidationGroup="g1"
                    ForeColor="Red" ValidationExpression="^[A-Z]{2}((0[1-9]|1[0-2])((0|1)[0-9]|2[0-9]|3[0-1])((19|20)\d\d))$">  
                </asp:RegularExpressionValidator>
                <br />
                <asp:Button Text="Submit" runat="server" ValidationGroup="g1" />
            </ContentTemplate>
        </asp:UpdatePanel>
    </div>
</asp:Content>

Code

C#

protected void txtUserID_TextChanged(object sender, EventArgs e)
{
    Page.Validate();
    if (Page.IsValid)
    {
        // Process stuff
        ScriptManager.RegisterClientScriptBlock(this, this.GetType(), "", "alert('Valid.')", true);
    }
}

VB.Net

Protected Sub txtUserID_TextChanged(sender As Object, e As EventArgs)
    Page.Validate()
    If Page.IsValid Then
        ' Process stuff
        ScriptManager.RegisterClientScriptBlock(Me, Me.GetType(), "", "alert('Invalid.')", True)
    End If
End Sub

Screenshot

Hi Dharnendra,

Sorry about that sql code I posted. It was supposed to be a trimmed down version of the complete code I am using.

That unfortunately, was not the reason the code doesn't work.

As previously stated, using Page.IsValid succeeeds in doing just one thing, it allows the regular expression validator to validate user input. If any user input does not conform to the format of the regular expression, it stops the user from continuin.

This part works. However, if user's input is in the correct format, the Page.IsValid method does not work because it does not check the conditions of the sql code.

The sql code says if user already exists on the database, display message to the user. If the user has already submitted the form, redirect user to another page. If this is the first time user is submitting the form, let the user know that as well.

I tried using button click event.This approach works great.

Below is the complete code that I have come up with using button click event. If you run it, you will see it works exactly like we want it to work.

Notice also that we removed the requirement for upper case characters by changing from A-Z to A-Za_z in the Regular Expression Validator. This way, we can convert to upper case when presenting report of the subscribers using SQL Server UPPER() function.

You can accept this as the solution if it works for me. It works for us.

//CSS

<style type="text/css">
.button {
  display: inline-block;
  padding: 15px 25px;
  font-size: 14px;
  cursor: pointer;
  text-align: center;
  text-decoration: none;
  outline: none;
  color: #fff;
  background-color: #04AA6D;
  border: none;
  border-radius: 15px;
  box-shadow: 0 9px #999;
}

.button:hover {background-color: #3e8e41}

.button:active {
  background-color: #3e8e41;
  box-shadow: 0 5px #666;
  transform: translateY(4px);
}
</style>

//HTML

<span style="font-size: 14pt;"> Enter First letter of first name, first letter of last name, 2 digit day, 2 digit month and 4 digit year. Example: John Doe will be JD01301999</span>
<asp:TextBox ID="txtUserId" maxlength="10" placeholder="Enter Combination of and DOb..." Style="width: 250px;" class="form-control"
    runat="server"></asp:TextBox>
 <asp:RequiredFieldValidator
ID="RequiredFieldValidator5"
runat="server" style="font-weight:bold;"
ErrorMessage="Employee ID is required!"
ControlToValidate="txtUserId"
Display="Dynamic"
ValidationGroup="dte1"
ForeColor="Red">
</asp:RequiredFieldValidator>
<asp:RegularExpressionValidator ID="regvaldob" ValidationGroup="dte1" runat="server"
    ControlToValidate="txtUserId" Display="Dynamic" style="font-weight:bold;" 
    ErrorMessage="Invalid format. Use example of John Doe born January 1st 1900 as JD01011900!"
    ForeColor="Red" ValidationExpression="^[A-Za-z]{2}((0[1-9]|1[0-2])((0|1)[0-9]|2[0-9]|3[0-1])((19|20)\d\d))$">  
</asp:RegularExpressionValidator><br />
<asp:Button ID="btn_check" runat="server" Text="Click here to verify badge number" CssClass="button" CausesValidation="true" OnClick="btn_check_Click" ValidationGroup="dte1" /><br />
<br />

Protected Sub btn_check_Click(ByVal sender As Object, ByVal e As EventArgs) Handles btn_check.Click
     If Not String.IsNullOrEmpty(txtUserId.Text.Trim()) Then
        emplabel.Text = ""
        txtUserId.Style("border-color") = ""
        Dim Conn As SqlConnection
         
        'Read in connection String
        Conn = New SqlConnection(ConfigurationManager.ConnectionStrings("constr").ConnectionString)
        Conn.Open()
        Dim cmd As New SqlCommand(" SELECT e.empID,e.employeename, e.previousYear, e.thisYear, d.dateCreated FROM emp e inner join dateTable d on e.employeeID = d.employeeID WHERE e.EmpID=@empID ORDER By d.dateCreated DESC", Conn)
        cmd.CommandType = CommandType.Text
        cmd.Parameters.AddWithValue("@empID", txtUser.Text)
 
        Dim dr As SqlDataReader = cmd.ExecuteReader()
        If dr.HasRows Then
            'Employee exists'
            dr.Read()
            checkusername.Visible = True
            dprocessed.Visible = True
            If dr("previousYear").ToString() = "1" AndAlso dr("thisYear").ToString() = "0" Then
                imgstatus.ImageUrl = "images/warning-39.png"
                lblStatus.Text = "Existing record found! Please verify your information for accuracy. Then complete rest of the form."
                lblStatus.ForeColor = System.Drawing.Color.Red
                System.Threading.Thread.Sleep(300)
                txteName.Text = dr("employeeName").ToString()
                txttitle.Text = dr("empTitle").ToString()
                txtemail.Text = dr("email").ToString()
                txtUserId.Text = dr("empID").ToString()
                fillRecords()
 
            ElseIf (dr("thisYear").ToString() = "1" AndAlso dr("previousYear").ToString() = "1") OrElse (dr("thisYear").ToString() = "1" AndAlso dr("previousYear").ToString() = "0") Then
                Response.Redirect("alreadycompleted.html")
 
                GridPanels.Enabled = False
                dprocessed.Visible = True
                btnNext.Enabled = False
                fillRecords()
            Else
                'not this year, nor the previous year'
            End If
        Else
            checkusername.Visible = True
            dprocessed.Visible = True
            imgstatus.ImageUrl = "images/Icon_Available.gif"  'User's first time submitting this form
            lblStatus.Text = "Looks like this is your first time completing this form. Proceed to complete entire form"
            lblStatus.ForeColor = System.Drawing.Color.Red
            System.Threading.Thread.Sleep(300)
            txteName.Text = ""
            txttitle.Text = ""
            txtemail.Text = ""
        End If
    Else
        checkusername.Visible = False
    End If
End Sub