How to check if an input passed in $_POST is not empty?

Question

Possible Duplicate:
Check whether $_POST-value is empty

I am using this code to validate if the passed input is not empty, but this fails when I use "white space" in the input. It does pass the empty() check.

if (empty($_POST['r_user'])) {
    $data['error'] = 'Please pick a username to continue.';
    $data['errorID'] = 'r_user';
}

What is the proper method to check an empty string in PHP?

score 4 · Accepted Answer · edited Dec 30 '13 at 16:00

4

You need to use trim function before checking the variable.

$trimUser= trim ($_POST['r_user']);

now execute the empty method.

edited Dec 30 '13 at 16:00

BenMorel

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answered Sep 17 '12 at 12:37

RK.

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Alex · Answer 2 · 2012-09-17T12:49:54.797

2

as per PHP documentation suggestion, your code would become:

if (trim($_POST['r_user']) == false) {
    $data['error'] = 'Please pick a username to continue.';
    $data['errorID'] = 'r_user';
}

edited Sep 17 '12 at 12:49

answered Sep 17 '12 at 12:35

Alex

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NullPoiиteя · Answer 3 · 2012-09-17T12:45:14.623

1

you can trim() removes white space from the beginning and end of a string

working example

      $test = "      ";
      if(trim($test)){
         if (empty($test))
             echo "true";
         else
             echo "false";
      }

live : check this on codepad

edited Sep 17 '12 at 12:45

answered Sep 17 '12 at 12:34

NullPoiиteя

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Fluffeh · Answer 4 · 2012-09-17T12:39:45.370

0

You can use trim nicely here, it removes whitespace front and back:

if (empty(trim($_POST['r_user']))) { // Incorrect!

Edit, wow, learned a new thing today.

This will however work:

$var=trim($_POST['r_user']);
if (empty($var)) {

Working Example:

 <?php 
    $var='    ';
    $var=trim($var);
    if(empty($var))
        echo "Yay";
    else
        echo "Nay!";

 ?>

Output:

Yay

edited Sep 17 '12 at 12:39

answered Sep 17 '12 at 12:34

Fluffeh

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PHP docs warn that `empty(trim())` produces an error. – Alex Sep 17 '12 at 12:35
http://codepad.org/7QuJPRrF - produces an error. Have to trim it first, then check if it's empty. – Travesty3 Sep 17 '12 at 12:35
Okay, learned a new thing about trim, but the code above now works. – Fluffeh Sep 17 '12 at 12:40

OctoD · Answer 5 · 2012-09-18T07:45:45.070

0

if ( empty( trim( $_POST['r_user'] ))) {

// wrong! gives an error - learned something new :) // the right way should be :

$myvar = trim( $_POST['r_user'] ); 

if ( empty( $myvar )) {

or

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

edited Sep 18 '12 at 07:45

answered Sep 17 '12 at 12:36

OctoD

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http://php.net/manual/en/function.empty.php specifies that empty(trim()) will produce an error. – Alex Sep 17 '12 at 12:39
I doubt you use the first one, since you can't pass functions to `empty()` – Patrick Q Sep 17 '12 at 12:40
Mistake ^^ sorry, learned something new :) – OctoD Sep 17 '12 at 12:42
so you also learnt after fluflleh very nice of you :):):):):) – NullPoiиteя Sep 17 '12 at 12:44
No offense, but you should probably edit out the sentence stating that you 'usually use' something that doesn't work :^) – Alex Sep 18 '12 at 06:58

score 0 · Answer 6 · answered Sep 17 '12 at 12:36

0

You may use :

$var = '';
if (array_key_exists('r_user', $_POST)) {
  $var = trim($_POST['r_user']);
} 
if (empty($var)) {
   // do some stuffs
}

instead.

answered Sep 17 '12 at 12:36

Alain Tiemblo

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You can't pass a function to `empty()` – Patrick Q Sep 17 '12 at 12:38

EbinPaulose · Answer 7 · 2012-09-17T13:00:10.297

-1

if(isset($_POST['r_user'])){
           // ur code
           }

edited Sep 17 '12 at 13:00

answered Sep 17 '12 at 12:45

EbinPaulose

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How to check if an input passed in $_POST is not empty?

7 Answers7