CODEWITHSUNDEEP
phpvalidationisset
Stumbler
Stumbler

Reputation: 2146

PHP: isset () not working (false negatives)

Okay, I know that there are a few of these questions already on SO; but they don't actually solve my problem.

For this (cut-down) html form:

<!DOCTYPE html><html><head><title>test</title></head><body>
        <form method="post" autocomplete="on" action="application6.php">
            <p>
                <input  type="text" name="fullname" id="fullname" maxlength="50" size="30">
                <label for="fullname">*Full Name</label>
            </p>
            <p>
                <input  type="text" name="email" id="email" maxlength="50" size="30">
            </p>
            <p>
                <select name="hours" id="hours">
                    <option value="" disabled="disabled" selected="selected">*Hours</option>
                    <option value="0">0</option>
                    <option value="1">1</option>
                    <option value="2">2</option>
                </select>
            </p>
    </body>
</html>

I have the following code 

$error_array = array(
    " "
);

echo ("debug: ");
print_r($_POST);



$variables = array(
    'fullname',
    'email',
    'hours'
);

foreach ($variables as $variable_name) {

    if (isset($_POST[$variable_name])) {
        echo 'Variable: ' . $variable_name . ' is not set<br/>';
        array_push($error_array, " " . $variable_name);
    }


}

This results, in the submission of a blank form, in the output of

debug: Array ( [fullname] => [email] => )

An alternative is to check if these elements are empty(), but empty() will return false positives for when "hours" is set to 0.

Why are these elements incorrectly registering as being set, and what means can successfully test inputs of different types?

Upvotes: 0

Views: 1350

Answers (4)

ArtisticPhoenix
ArtisticPhoenix

Reputation: 21671

Hi there is no need to check if isset because it will always be set you only need to check for this

if( trim($_POST['key']) != '' ){

}

Also if you really need to use the isset 

$post = array_filter( array_map('trim', $_POST), function($a){
      return $a != '';
});

That will remove them from $post

Upvotes: 0

rafaelphp
rafaelphp

Reputation: 279

if (isset($_POST[$variable_name])) {
    echo 'Variable: ' . $variable_name . ' is set!!<br/>';
} elseif(!isset($_POST[$variable_name])){
    array_push($error_array, " " . $variable_name);
} elseif( empty($_POST[$variable_name])){
    echo 'Variable: ' . $variable_name . ' is empty!!<br/>';
} else{
   var_dump($_POST[$variable_name])
}

Upvotes: 0

Derokorian
Derokorian

Reputation: 1440

The problem is in your logic, you check if $_POST[whatever] isset, and if so, you then output "Variable is NOT set" this is the opposite of what you're if statement checks. Try adding a ! in front of isset:

if (!isset($_POST[$variable_name])) {
    echo 'Variable: ' . $variable_name . ' is not set<br/>';
    array_push($error_array, " " . $variable_name);
}

Upvotes: 5

Cohan
Cohan

Reputation: 4544

try making sure the trimmed value is not an empty string and that the variable exists

foreach ($variables as $variable_name) {

    if (isset($_POST[$variable_name]) && "" != trim($_POST[$variable_name]) ) {
        echo 'Variable: ' . $variable_name . ' is not set<br/>';
        array_push($error_array, " " . $variable_name);
    }
}

Upvotes: 0

Related Questions