php undefined index with isset $_POST
Question
trying to create a chat and keep getting Undefined index i've tried adding ? $_POST['chat'] : null; ? $_POST['chat'] : null; but doesn't work
Notice: Undefined index: chat in /Applications/MAMP/htdocs/chat/chat.php on line 8
Line 8:
$sent = $_POST['chat'];
the variable is used here:
if (isset($_POST['chat'])) {
if (!empty($sent)) {
fwrite($myfile, $first.': '.$txt.'=');
fclose($myfile);
} else if (empty($sent)) {
if(isset($_POST['chat'])){
echo 'Cant send an empty message','<br />';
}
}
}
HTML:
<body>
<iframe id='reload' src='refresh.php'>
<fieldset class="field">
<div id="list"><p><?php
$filename = 'chat.txt';
$handle = fopen($filename, 'r');
$detain = fread($handle, filesize($filename));
$chat_array = explode('=', $detain);
foreach($chat_array as $chat) {
echo $chat.'<br />';
}
?></p></div>
</fieldset>
</iframe>
<form action="chat.php" method="POST">
<input type="text" name="chat" class="textbox">
<input type="submit" value="Send" class="button">
</form>
</body>
Variables:
$sent = $_POST['chat'];
$myfile = fopen("chat.txt", 'a') or die("Unable to open file!");
$txt = ($sent."\n");
$first = getuserfield('username');
$active = ($first.":".$ip_addr);
$activef = fopen("ip-user.txt", 'a');
$myFile = "domains/domain_list.txt";
Edit: This is not a duplicate because this is for a very specific piece of code, i've also already used empty and I would not like to ignore the problem because it is a possible cause of another problem.
Thank you.
4 answers
solution1
1 2016-04-30 05:40:08
You said you tried a ternary conditional, but didn't post an example of what you tried. It should look like this:
$sent = isset($_POST['chat']) ? $_POST['chat'] : null;
In PHP 7.0 or higher, you can simplify this expression with the null coalesce operator :
$sent = $_POST['chat'] ?? null;
solution2
1 ACCPTED 2016-04-30 05:41:42
Use this code :
<?php
$sent = '';
if(isset($_POST['chat']))
{
$sent = $_POST['chat'];
if (!empty($sent))
{
$txt = ($sent."\n");
fwrite($myfile, $first.': '.$txt.'=');
fclose($myfile);
}
else
{
echo 'Cant send an empty message','<br />';
}
}
?>
solution3
0 2016-04-30 05:30:49
did you submit the form ?
PHP:
if (isset($_POST['chat'])) {
if (!empty($sent)) {
fwrite($myfile, $first.': '.$txt.'=');
fclose($myfile);
} else if (empty($sent)) {
if(isset($_POST['chat'])){
echo 'Cant send an empty message','<br />';
}
}
}
HTML:
<form action="" method="POST">
<input type="text" name="chat">
<input type="submit" name="submit">
</form>
solution4
0 2016-04-30 05:42:16
Do something like $sent = isset($_POST['chat']) ? $_POST['chat'] : ''; $sent = isset($_POST['chat']) ? $_POST['chat'] : '';
btw.: There is much redundance in you code.
if (isset($_POST['chat'])) {
if (!empty($sent)) {
fwrite($myfile, $first.': '.$txt.'=');
fclose($myfile);
} else {
echo 'Cant send an empty message','<br />';
}
}
If you don't want to write an isset() condition every time, you could define a short function:
function get(&$var, $default = null)
{
return isset($var) ? $var : $default;
}
Use it like that:
$sent = get($_POST['chat'], '');
or just
$sent = get($_POST['chat']);
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