PHP form error - Warning: Invalid argument supplied for foreach()

Question

I am a beginner to PHP, currently working on a long survey. Below is the code which is causing issues, the data from the checked boxes are added to a database:

$_q4 = (isset($_GET['check_q4']) ? $_GET['check_q4'] : null);
$q4 = '';
foreach($_q4 as $a4) {
$q4 .= $a4;}


<div class="group v-group">
<label><input type="checkbox" name="check_q4[]" value="1"> Checkbox 1</label>
<label><input type="checkbox" name="check_q4[]" value="2"> Checkbox 2</label>
<label><input type="checkbox" name="check_q4[]" value="3"> Checkbox 3</label>
</div>

Error:

Warning: Invalid argument supplied for foreach() in C:\inetpub\wwwroot\submit_form.php on line 79 Failed to run query: SQLSTATE[22001]:

Many thanks for you help.

possible duplicate of [Invalid argument supplied for foreach()](http://stackoverflow.com/questions/2630013/invalid-argument-supplied-for-foreach) — Narendrasingh Sisodia, May 12 '15 at 08:59
Can you echo out the contents of your `$_q4` variable? It sounds like the $_GET variable is empty, so `null` is being assigned to the variable. Are you actually posting the form via "GET", or are you posting via the "POST" method? — VerySeriousSoftwareEndeavours, May 12 '15 at 09:00

score 3 · Accepted Answer · answered May 12 '15 at 08:59

3

Since $_q4 can be null, you should check if it is the case, because you cannot traverse an empty/null variable with foreach.

Try with something like this:

if(!empty($_q4)){
  foreach($_q4 as $a4) {
   $q4 .= $a4;
  }
}

answered May 12 '15 at 08:59

Masiorama

1,066
17
26

score 0 · Answer 2 · answered May 12 '15 at 09:05

0

Please make sure that your Form's request method is get

$_q4 = (isset($_GET['check_q4']) ? $_GET['check_q4'] : null);
$q4 = '';
if(is_array($_q4)){
  foreach($_q4 as $a4) {
  $q4 .= $a4;}
}

answered May 12 '15 at 09:05

kamal pal

4,187
5
25
40

PHP form error - Warning: Invalid argument supplied for foreach()

2 Answers2