How to check for empty form variable on page load

Question

I have a html form that is checked by PHP. When the page loads php errors stating missing variable because form has not been submitted. It works fine once I put something in the form and submit. But on first page load it errors.

Error on page load Notice: Undefined index: sk in index.php on line 65 Notice: Undefined index: sk in index.php on line 78

<form action=# method="post">
Source Key: <input type="text"  name="sk">
</br>
<input type="submit">
</form>



<?php


     if(isset($_POST['submit']))
{
        $test = $_POST['sk'];//assigning your input value

        if(isset($test))
        {
            $fr=fopen("php://stdin","r");   // open file pointer
            $input = fgets($fr,128);        // read 128 char max
            $input = rtrim($input);         // trim any trailing spaces
            fclose ($fr);                   // close the file handle
            $result =  $input;              // return the text 
        }
    } 
?>

You have entered : <?php echo $_POST["sk"]; 
echo "</br></br>";

`You have entered : ";` should be `You have entered : ";` – devpro Mar 28 '19 at 18:58 — devpro, Mar 28 '19 at 18:58
thanks devpro worked great – Jay Parker Mar 28 '19 at 19:55 — Jay Parker, Mar 28 '19 at 19:55

score 1 · Answer 1 · answered Mar 28 '19 at 18:51

1

You can use isset

$value = (isset($_POST['value']) ? $_POST['value'] : 'alternative';

answered Mar 28 '19 at 18:51

Lulceltech

1,662
11
22

Ralph · Answer 2 · 2019-03-28T19:07:57.130

0

You have to name your submit

<input type="submit">

to:

<input type="submit" name="submit">

EDITED

then replace that part of ur php with:

<?php 
if(isset($_POST['submit'])) {
    echo "You have entered : ";
    echo $_POST['sk'];
    echo "</br></br>";
}
?>

edited Mar 28 '19 at 19:07

answered Mar 28 '19 at 18:51

Ralph

337
4
13

Your submit button does not need a name... – Lulceltech Mar 28 '19 at 18:52
@TimHinz https://stackoverflow.com/questions/7775512/using-ifisset-postsubmit-to-not-display-echo-when-script-is-open-is-not – Ralph Mar 28 '19 at 18:54
1

@TimHinz Actually it does, because of the `if(isset($_POST['submit']))` part (Although we both know that there's also an issue in this part of the code `echo $_POST["sk"]`) – Alon Eitan Mar 28 '19 at 18:55
@AlonEitan Yeah idk why he downvoted me for that when it's common knowledge... – Ralph Mar 28 '19 at 18:55
LMAO the only reason he needs it is because @AlonEitan is right. Otherwise there is 0 reason to name a submit button. In HTML 5 you do NOT need to name a submit button under normal circumstances. – Lulceltech Mar 28 '19 at 18:56
@TimHinz In the code he provided, he obviously requires it which is why I mentioned it. Had it not been needed I wouldn't have replied – Ralph Mar 28 '19 at 18:57
And you didn't point that out because? You linked to a 7 year old question that in no way pointed out that he did that. – Lulceltech Mar 28 '19 at 18:59
U r right but not related to submit – devpro Mar 28 '19 at 18:59
@TimHinz He didn't name his submit while using isset so I told him he has to name it. I don't understand what you're trying to argue here when we both know that isset submit wont work without having named your submit button. – Ralph Mar 28 '19 at 19:09
Because until @AlonEitan pointed out im pretty sure you were just taking a guess... lol – Lulceltech Mar 28 '19 at 19:10

How to check for empty form variable on page load

2 Answers2