“Notice: Undefined index” error when using POST

Question

I am starting to get the hang of web development. I am facing a minor problem which is the following: Undefined index: username

I know it is because of the fact that I am using GET but the actual php script works and changes ARE MADE to the db - which is good. What is not good is the fact that this error is being displayed to the user: Undefined index: username

This is my code:

<!doctype html>
    <form id='register' action='changeticket.php' method='POST'>
    <input type="hidden" name="username" value="<?php echo $_GET['username']; ?>" >
    <fieldset >
    <legend>Change ticket</legend>
    <label for='ticket' >Proposed ticket request number: </label>
    <input type='text' name='ticketValue' id='tickets'  />
    <input type='submit' name='Submit' value='Submit' />
    </fieldset>
</form>
<?php
require "init.php";

if(!empty($_POST['ticketValue']) && !empty($_POST['username'])){
    $ticketValue = $_POST['ticketValue'];
    $stmt = "UPDATE ticketTable SET ticket = ? WHERE username = ?";
    $result = $dbcon->prepare($stmt);
    $result->bind_param('ss', $ticketValue, $username);
    $result->execute();
    echo "Ticket has been changed";
} 
else{
    echo "Not able to make changes sorry";
}
?>

I don't want to make the parameters visible in the url after i click submit so I am using POST. Like I said it works, but the error Undefined index: username is being displayed.

How can I fix this?

Thanking you

where is the username varaible come from? You can use the isset func to avoid these notice , please. — SuperBear, Mar 24 '16 at 03:15

score 3 · Accepted Answer · answered Mar 24 '16 at 03:17

3

One option is to use $_REQUEST instead of $_GET. $_REQUEST has both variables ( $_GET and $_POST)

answered Mar 24 '16 at 03:17

Lucas Gonzalez

106
7

This is the correct answer. – Lightness Races in Orbit Mar 24 '16 at 03:25
You my friend are a star! Not sure how to thank you other than a +1 and accepted answer!!! Many thanks for this - it instantly fixed my problem. Just out of curiosity what is $_REQUEST and can it be used everywhere? – Mar 24 '16 at 03:33
You'll still get the warning if you go to the page with a URL that has no `username=xxx` parameter. – Barmar Mar 24 '16 at 03:35
You should change it to ` – Barmar Mar 24 '16 at 03:36

score 0 · Answer 2 · answered Mar 24 '16 at 03:12

You forgot to initialize $username..

    <!doctype html>
    <form id='register' action='changeticket.php' method='POST'>
    <input type="hidden" name="username" value="<?php echo $_GET['username']; ?>" >
    <fieldset >
    <legend>Change ticket</legend>
    <label for='ticket' >Proposed ticket request number: </label>
    <input type='text' name='ticketValue' id='tickets'  />
    <input type='submit' name='Submit' value='Submit' />
    </fieldset>
</form>
<?php
require "init.php";

if(!empty($_POST['ticketValue']) && !empty($_POST['username'])){
    $ticketValue = $_POST['ticketValue'];
    $username = $_POST['username'];
    $stmt = "UPDATE ticketTable SET ticket = ? WHERE username = ?";
    $result = $dbcon->prepare($stmt);
    $result->bind_param('ss', $ticketValue, $username);
    $result->execute();
    echo "Ticket has been changed";
} 
else{
    echo "Not able to make changes sorry";
}
?>

That will cause an undefined variable warning, not undefined index. — Barmar, Mar 24 '16 at 03:17
but ur script may not work , because u have not defined $username — Aamir, Mar 24 '16 at 03:20
This is true and a good observation (and makes me wonder how the OP thinks the DB changes are being made correctly). Not the actual problem being asked about, though. — Lightness Races in Orbit, Mar 24 '16 at 03:26

score -2 · Answer 3 · answered Mar 24 '16 at 03:14

-2

Since you are using POST method instead of GET method to send the parameters, then you should change the following part:

<input type="hidden" name="username" value="<?php echo $_GET['username']; ?>" >

To:

<input type="hidden" name="username" value="<?php echo $_POST['username']; ?>" >

answered Mar 24 '16 at 03:14

skangmy

117
1
3
10

And now your first load is broken, with the same problem. – Lightness Races in Orbit Mar 24 '16 at 03:25

“Notice: Undefined index” error when using POST

3 Answers3