validate form in php

Question

I'm trying to validate a form of a test. I get an error in answer.php Basically I want to validate that each question has been answered.

The form:

$sql1="SELECT * FROM ex_question WHERE test_name = '$tid' ORDER BY q_nr";
$result1=mysql_query($sql1);
echo "<form method='post' name='form1' action='answer.php'>";
while($row1 = mysql_fetch_array($result1))
{
    $q_nr=$row1['q_nr'];
    $q_type=$row1['q_type'];
    $question=$row1['question'];
    $option1=$row1['option1'];
    $option2=$row1['option2'];
    $option3=$row1['option3'];
echo "<P><strong>$q_nr $question</strong><BR>";
echo "<BR>";
echo "</p>";
if ($q_type != 'mr') {
if($option1!="") {
echo "<input type='radio' name='question[$q_nr]' value='A'>$option1<BR>";
} else {
echo ''; }
if($option2!="") {
echo "<input type='radio' name='question[$q_nr]' value='B'>$option2<BR>";
} else {
echo ''; }
if($option3!="") {
echo "<input type='radio' name='question[$q_nr]' value='C'>$option3<BR>";
} else {
echo ''; }
} else { // else if not <> mr
if($option1!="") {
echo "<input type='checkbox' name='question[$q_nr][]' value='A'>$option1<BR>";
} else {
echo ''; } 
if($option2!="") {
echo "<input type='checkbox' name='question[$q_nr][]' value='B'>$option2<BR>";
} else {
echo ''; } 
if($option3!="") {
echo "<input type='checkbox' name='question[$q_nr][]' value='C'>$option3<BR>";
} else {
echo ''; } 
} //end else if q_type <> mr
    echo "<BR>";
    echo "</p>";
} //end while row1
echo "<input type='submit' value='Submit' name='Submit'>";
echo "</form>";

answer.php

foreach($_POST['question'] as $key => $ans) {
if ($ans[] = '') {
echo "answer is empty";
}
}

I get the error: Warning: Invalid argument supplied for foreach() in ......

possible duplicate of Invalid argument supplied for foreach() — Gajus
– Gajus, Commented Apr 10, 2014 at 6:33

Mark · Accepted Answer · 2011-10-06 10:13:55Z

2

One thing is that you are assigning the answer rather than checking it, use ==

foreach($_POST as $key => $ans) {
  if ($ans == '') {
    echo "answer is empty";
  }
}

and instead of using

name='question[$q_nr]'

I would use for the radio fields

name='question_{$q_nr}'

and for the checkboxes

name='question_{$q_nr}[]'

On answer.php you should be able to do a print_r($_POST) to check what you are getting.

edited Oct 6, 2011 at 10:13

answered Oct 6, 2011 at 9:13

Mark

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6 Comments

Wilest Over a year ago

I've done what you suggested: 1. Changed to echo "<input type='radio' name='question_$q_nr[]' value='A'>$option1<BR>"; but now I get an error: Parse error: syntax error, unexpected ']', expecting T_STRING or T_VARIABLE or T_NUM_STRING in ...

Mark Over a year ago

Sorry meant to wrap in curly braces, have changed above.

Mark Over a year ago

The curly braces explicitly specify the end of the name of the variable.

Wilest Over a year ago

Thank you Mark, I've changed the form, and also changed the action page to use == instead of = but it's still complaining, I'll keep on trying and report back.

Mark Over a year ago

You will also have to change the foreach statement as your post names are no longer the question array they are 'question_1','question_2'

|

M. Suleiman · Accepted Answer · 2011-10-06 10:38:19Z

1

This is probably because your $_POST['question'] is empty. This is what happens when you try to do this with an empty array.

Whereas your HTML says: name='question[$q_nr]'.

Print the values in the array to see what it contains, use print_r.

Edit: $_POST['question'] IS NOT an array! While $_POST IS an array...

Maybe you should try to do something like this: foreach ($_POST as $key => $value)

Or do it however you want the result to be displayed.

edited Oct 6, 2011 at 10:38

answered Oct 6, 2011 at 10:11

M. Suleiman

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7 Comments

Wilest Over a year ago

Thank you, I used print_r($_POST); and get the output: Array ( [question_1] => A ) and then underneath it: Warning: Invalid argument supplied for foreach()

M. Suleiman Over a year ago

try

if( is_array( $_POST['question'] ) ) {     foreach ( $_POST['question'] as $key=>$value ) { ... } else {     echo "$_POST['question'] isn't an array"; }

and think of variable variables

M. Suleiman Over a year ago

wait a minute... How come $_POST['question'] is an array in your case? in your case $_POST IS an array, but not $_POST['question']

Wilest Over a year ago

OK you have put me in the right direction here. If I only use $_POST in my foreach I don't get the error any more, but my if statement still gives no output to validate the form. Sigh.

Wilest Over a year ago

Still wanted to add:

foreach($_POST as $key => $ans) { echo $key; echo $ans; if (empty($_POST)) { echo "empty"; } else { echo "not empty"; } }

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