php variable undefined index on isset() submit

Question

Im sorry if this is a stupid question but ive been stuck on this for hours, the closest answer I got was from this post but the issue is not resolved.

Im getting data from checkboxes from a simple form. The forms action takes user to next page, I get the values from checkboxes using

$event = $_Post['matchId'];
var_dump($event) confirms values has been received correctly(see image)

enter image description here

The value of $event is an array so im doing the following

foreach($event as $key => $eventId)
//some code

All is working in the forloop however as soon as I click submit the isset() function gets trigered I get error:

Undefined Index: matchId

Invalid Argument for forloop

Any idea what I am doing wrong here Please let me know if you require more info

update on requested isset code

    $event= $_POST['matchId'];
var_dump($event);
foreach($event as $key => $eventId){
$sql = "Select * FROM events WHERE event_id = $eventId";
$result = mysql_query($sql);

$i=0;//counter
while($row=mysql_fetch_array($result)){

    $team1 = $row['team1'];
    $team2 = $row['team2'];
    $id[$i]= $row['event_id']; 

    echo'<h3>'.$team1.' VS '.$team2.'</h3>';
    echo'<select name="id[]">';
            echo'<option value="'.$row['team1'].'">'.$team1.'</option>';
            echo'<option value="'.$row['team2'].'">'.$team2.'</option>';
            echo'</select>';    

            echo'By <select name="score[]">';
            echo'<option value="1">1</option>';
            echo'<option value="2">2</option>';
            echo'<option value="3">3</option>';
            echo'<option value="4">4</option>';
            echo'<option value="5">5</option>';
            echo'<option value="6">6</option>';
            echo'<option value="7">7</option>';
            echo'<option value="8">8</option>';
            echo'<option value="9">9</option>';
            echo'<option value="10">10</option>';
            echo'<option value="11">11</option>';
            echo'<option value="12">12</option>';
            echo'<option value="13">13</option>';
            echo'<option value="14">14</option>';
            echo'<option value="15">15</option>';
            echo'<option value="16">16</option>';
            echo'<option value="17">17</option>';
            echo'<option value="18">18</option>';
            echo'<option value="19">19</option>';
            echo'<option value="20">20</option>';
            echo'</select>';    
        $i++;
}//while
}//for
echo'</legend></fieldset>';
echo'<input type="submit" class="buttono" value="Submit" name="submit" />';
echo'</form>';
echo'</div><!--news-->';
if(isset($_POST['submit'])){    
$x=0;
foreach($_POST['id'] as $key => $winner){
    $score = $_POST['score'][$key];
    var_dump($score);
    $winnerb = $id[$key];
    echo($winner."-".$winnerb);
    $sql="INSERT INTO picks(member_nr,event_id,pick,score)
            VALUES('$userId','$winnerb','$winner','$score')";
            mysql_query($sql) or trigger_error(mysql_error()." in ".$sql);
}//for
}//end isset

You should make up your mind, switching back and forth between id and matchId you are just wasting everybody's time. — jeroen
– jeroen, Commented Apr 22, 2015 at 8:53

Sougata Bose · Accepted Answer · 2015-04-22 08:54:52Z

0

The error is on this part -

$event= $_POST['matchId'];
var_dump($event);
foreach($event as $key => $eventId){
$sql = "Select * FROM events WHERE event_id = '$event'";
$result = mysql_query($sql);
.....

$_POST['matchId'] is not present. You should add a check for this like -

if (!empty($_POST['matchId'])) { //fetch & display data }
else { //display some error or something like this }

$event event is empty in this case as $_POST['matchId'] is missing. So it is giving the error regarding foreach.

answered Apr 22, 2015 at 8:54

Sougata Bose

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Comments

jeroen · Accepted Answer · 2015-04-22 08:42:03Z

0

If no checkbox is set, $_POST['id'] will not be set so that will lead to that warning.

Also note that you cannot rely on the $key value unless you explicitly set that value of the key in the name attribute of your input element. The image of your var_dump() suggests that you are not doing that.

You also have an sql injection problem. You should switch to PDO or mysqli and use a prepared statement with bound variables.

answered Apr 22, 2015 at 8:42

jeroen

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