Form submit even it isn't filled

Question

I have an PHP guestbook. So I can write nothing into the form and submit, then it posts. Can I avoid this?

Here is my PHP code:

if (isset($_POST["Name"]) &&
    isset($_POST["Email"]) &&
    isset($_POST["Überschrift"]) &&
    isset($_POST["Kommentar"])) {
        $daten = array("überschrift" => $_POST["Überschrift"],
                       "eintrag" => $_POST["Kommentar"],
                       "autor" => $_POST["Name"],
                       "email" => $_POST["Email"],
                       "datum" => date("d.m.Y"));
        $daten = base64_encode(serialize($daten));
        if(!file_exists("gaestebuch.txt")) {
            $datei = fopen("gaestebuch.txt", "xb");
            fclose($datei); 
        }
        $altdaten = file_get_contents("gaestebuch.txt");
        if (file_put_contents("gaestebuch.txt", "$daten\r\n$altdaten") ) {
            echo "Eintrag hinzugefügt!";
        } else {
            echo "Fehler!";
        }
}

or use javascript to do this, to prevent the form from being submitted — hassan, Mar 06 '17 at 07:55
use isset and !empty for all variables like this if (isset($_POST["Name"]) && !empty($_POST["Name"])) — Javed Sayyed, Mar 06 '17 at 07:55
Please don't overwrite your questions with an answer, it is hard for new readers to understand what the problem was if you ask a question featuring working code. The answer below is more than sufficient. — halfer, Mar 06 '17 at 22:56
@halfer thanks for the information i will keep that in mind. — c.Bauer, Mar 07 '17 at 07:46

Luke Bradley · Accepted Answer · 2017-03-06T09:05:44.777

Check the the first value ISSET so you know it is a POST request then check if the rest are empty

if (isset($_POST["Name"]) &&
    !empty($_POST["Email"]) &&
    !empty($_POST["Überschrift"]) &&
    !empty($_POST["Kommentar"])) {
        $daten = array("überschrift" => $_POST["Überschrift"],
                       "eintrag" => $_POST["Kommentar"],
                       "autor" => $_POST["Name"],
                       "email" => $_POST["Email"],
                       "datum" => date("d.m.Y"));
        $daten = base64_encode(serialize($daten));
        if(!file_exists("gaestebuch.txt")) {
            $datei = fopen("gaestebuch.txt", "xb");
            fclose($datei); 
        }
        $altdaten = file_get_contents("gaestebuch.txt");
        if (file_put_contents("gaestebuch.txt", "$daten\r\n$altdaten") ) {
            echo "Eintrag hinzugefügt!";
        } else {
            echo "Fehler!";
        }
}

also consider using OR instead of &&

!empty($_POST["Email"]) OR
!empty($_POST["Überschrift"]) OR
!empty($_POST["Kommentar"]))

This means if only one of the fields is empty it will fail instead of only when all of the fields are empty

score 0 · Answer 2 · edited May 23 '17 at 12:00

0

By nothing do you mean white space? If so just check so in a if statement. (credit)

if (trim($str) == '')
{
    //string is only whitespace
}

edited May 23 '17 at 12:00

Community

1
1

answered Mar 06 '17 at 07:58

marmeladze · Answer 3 · 2017-03-06T08:32:23.770

Consider below lines.

php > $a = '';
php > echo isset($a) ? 'a is set' : 'a is not set';
a is set
php > echo empty($a) ? 'a is empty' : 'a is not empty';
a is empty

setting something doesn't mean that it is not empty. so, use isset($foo) && !empty($foo) .

better create a function,

function present($x) {
  return (isset($x) && !empty($x));
}

and use it.

if (present($_POST['foo'])) {
 /* do something */ 
}

or do it for whole $_POST array,

function present($somevar) {
  return (isset($somevar) && !empty($somevar));
}

function all_vars_are_ok($arr) {
  $x = array_map("present", $arr);
  return (array_filter($x) == $x);
}

then,

if(all_vars_are_ok($_POST)) {
  /*
  *  do something 
  */
}

i now have a solution like isset($_POST["Name"]) && (!empty($_POST["Name"])) — c.Bauer, Mar 06 '17 at 08:05

score 0 · Answer 4 · answered Mar 06 '17 at 08:14

0

Solutions:

Your can put attribute required in input tag.
You can add JavaScript validation.
In PHP you can check like this: !empty($variable)

answered Mar 06 '17 at 08:14

Sazzad Hussain

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Form submit even it isn't filled

4 Answers4