CODEWITHSUNDEEP
c#asp.netrequiredfieldvalidator
shujaat siddiqui
shujaat siddiqui

Reputation: 1577

Required Field Validator in code behind C#

I am trying to use required field validator in code behind file but it is showing the following error.

Error:

Unable to find control id 'TextBox1' referenced by the 'ControlToValidate' property of 'abcd854'

Note: TextBox1 exists in the page; I have tested it.

enter image description here

Aspx Page

  <%@ Page Title="Home Page" Language="C#" MasterPageFile="~/Site.master" AutoEventWireup="true"
    CodeBehind="Default.aspx.cs" Inherits="WebApplication3._Default" %>

<asp:Content ID="HeaderContent" runat="server" ContentPlaceHolderID="HeadContent">
</asp:Content>
<asp:Content ID="BodyContent" runat="server" ContentPlaceHolderID="MainContent">
    
    <p>
        <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
        <asp:Button ID="Button1" runat="server" Text="Button" ValidationGroup="save" />       
    </p>
    <p>
        &nbsp;<asp:ValidationSummary ID="ValidationSummary1" runat="server" />
</asp:Content>

Cs File

   public partial class _Default : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            //RequiredFieldValidator validator = ControlsValidation.AssignRequiredFieldValidatorToControl(TextBox1, "Field is required", "*", "save");
            //validator.ControlToValidate = ((TextBox)this.Form.FindControl("MainContent").FindControl("TextBox1")).ID;


            RequiredFieldValidator validator = new RequiredFieldValidator();
            validator.ID = "abcd" + new Random().Next(100, 1000);
            validator.ControlToValidate = ((TextBox)this.Form.FindControl("MainContent").FindControl("TextBox1")).ID;
            validator.EnableClientScript = true;
            validator.ErrorMessage = "";
            validator.Text = "*";
            validator.ValidationGroup = "save";
            validator.Display = ValidatorDisplay.Dynamic;

            this.Controls.Add(validator);
        }
    }

Upvotes: 4

Views: 23590

Answers (4)

Venkataraghavan Yanamandram
Venkataraghavan Yanamandram

Reputation: 431

In ASP.NET, after rendering your page, the TextBox's id will be changed (see source code in browser). you can change its client id mode to static so that it won't change.

Add ClientIDMode="Static" in your textbox

<asp:TextBox ID="TextBox1" runat="server" ClientIDMode="Static"></asp:TextBox>

Upvotes: 1

shujaat siddiqui
shujaat siddiqui

Reputation: 1577

The issue was:

 this.Controls.Add(validator);

As we all can see, TextBox1 is in child page, meaning "Content Page", so when using the above line of code, it adds the control in the master page, in which there is no control with the id "TextBox1".

After replacing the above line of code with:

this.Form.FindControl("MainContent").Controls.Add(validator);

it's working perfectly.

Upvotes: 5

Jorge Castro
Jorge Castro

Reputation: 11

Try This...

Code behind

oTexbox1.Attributes["required"] = "true";

Upvotes: 1

Dan
Dan

Reputation: 1001

Try using ClientID instead of ID

RequiredFieldValidator validator = new RequiredFieldValidator();
validator.ID = "abcd" + new Random().Next(100, 1000);

validator.ControlToValidate = ((TextBox)this.Form
             .FindControl("MainContent").FindControl("TextBox1")).ClientID;

validator.EnableClientScript = true;
validator.ErrorMessage = "";
validator.Text = "*";
validator.ValidationGroup = "save";
validator.Display = ValidatorDisplay.Dynamic;

this.Controls.Add(validator);

Upvotes: -2

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