'Why hidden input field values can't be empty

I'm using PHP form to send user registration data and then handle it with PHP form. I need to register a few user types such as "normal users," "admin users," "edit enabled users," etc. Details requests for registration of every kind of user are different. But I hope to use the same formDataManagement.php file. When I click the "Submit" button, an error message shows.

Undefined array Key.

Form data section

<input type="hidden" id="companyname" name="companyname" value="">
<input type="hidden" id="regno" name="regno" value="">
<input type="hidden" id="farmaddress" name="farmaddress" value="">
<input type="hidden" id="role" name="role" value="admin">
<input type="hidden" id="designation" name="designation" value="manager">

formDataManagement.php

//if user signup button
if(isset($_POST['signup'])){
    $name = mysqli_real_escape_string($con, $_POST['name']);
    $email = mysqli_real_escape_string($con, $_POST['email']);
    $password = mysqli_real_escape_string($con, $_POST['password']);
    $conpassword = mysqli_real_escape_string($con, $_POST['conpassword']);
    $compName = mysqli_real_escape_string($con, $_POST['companyname']);
    $role = mysqli_real_escape_string($con, $_POST['role']);
    $regno = mysqli_real_escape_string($con, $_POST['regno']);
    $designation = mysqli_real_escape_string($con, $_POST['designation']);
    $farm_address = mysqli_real_escape_string($con, $_POST['farmaddress']);
    $resi_address = mysqli_real_escape_string($con, $_POST['resaddress']);
}

But after the process, it shows the following error.

Warning: Undefined array key "companyname" in C:\xampp\htdocs\test\admin\register\formDataManagement.php on line 15

Warning: Undefined array key "regno" in C:\xampp\htdocs\test\admin\register\formDataManagement.php on line 17

Warning: Undefined array key "farmaddress" in C:\xampp\htdocs\test\admin\register\formDataManagement.php on line 22

Can't I send empty values as hidden input values? Please advise solving this issue.

phpmultipartform-data


Solution 1:[1]

  1. Use hidden without type="hidden" like <input hidden id="companyname" name="companyname" value=""/>. You can set for type type="text".

  2. Also try to close elements: <input hidden type="text" id="companyname" name="companyname" value=""/> or </input>.

So here is perfect input element:<input hidden type="text" id="companyname" name="companyname" value=""/>

Solution 2:[2]

I can't determine the exact problem with only your currently given code, but the problem might be caused by any of the followings:

  • You didn't use POST method to send the data in the form.
  • You put the three input fields outside of the form.
  • Your submit button doesn't work properly, especially when you have a pre-submit JS function before submitting the form.
  • And more (please include more of your codes)

You definitely can send empty values as hidden input values. Although the content will be empty, it will never give out warnings.

From MDN (description of input="hidden"):

A control that is not displayed but whose value is submitted to the server.

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution Source
Solution 1 Valery Dremov
Solution 2

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