PHP: check if posted variable exists or assign null value

Question

This can be done in Javascript with isNAN instead of !isset. Using the example below - both forms post to my script, one without a value and one with a value. Is the below code a correct way to do this in PHP to assign a value if the post var is not present?

$mycheck = !isset($_POST['value']) ? 0 : $_POST['value'];

<? 
if($_POST) :
  $mycheck = !isset($_POST['value']) ? 0 : $_POST['value'];
  echo $mycheck;
endif;
?>

<!-- send value-->
<form action="" method="post">
  <select name="value">
    <option value="0">0</option>
    <option value="5">5</option>
  </select>
  <input type="submit" name="submit">
</form>

<!-- doesn't send value-->
<form action="" method="post">
  <input name="different_var">
  <input type="submit" name="submit">
</form>

Also stackoverflow.com/a/3803347/632951

Pacerier
– Pacerier

2015-01-26 12:45:57 +00:00
Commented Jan 26, 2015 at 12:45 — Pacerier
– Pacerier, Commented Jan 26, 2015 at 12:45

Mike B · Accepted Answer · 2012-07-20 16:11:29Z

6

Yes, that's an acceptable way of setting default values.

An alternative, introduced in PHP 5.3, is to omit the middle argument of your ternary expression:

$mycheck = $_POST['value'] ?: 0;

However, this will likely throw notices for trying to access an array with a non-existant key if $_POST['value'] isn't set. Therefore your original method is more-accepted.

answered Jul 20, 2012 at 16:11

Mike B

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7 Comments

Palladium Over a year ago

It should be $_POST['value'] instead of isset($_POST['value']), as per the OP's intentions.

VictorKilo Over a year ago

I think that isset() is perfectly acceptable for this solution. It will always give true or false, and will do exactly what the OP wants...

Laurence Tuck Over a year ago

so if the posted value is a string your method is acceptable, but if its an array its better to use my original method?

VictorKilo Over a year ago

I would think so. Ternary operators are looking for a true/false response and isset() will always give you that, even with an array.

Palladium Over a year ago

@Innate Sort of but not quite. It depends on whether the value is already defined (hence, if you had an undefined string $value, the abbreviated notation will still throw notices). However, notices are rarely ever worth paying attention to and almost certainly not worth writing longer code to avoid; a case of useless notices is where session_start() will throw notices at you if a session is already declared, even though you need session_start() on every page to extend the session.

|

Palladium · Accepted Answer · 2012-07-20 16:12:30Z

1

It works, but there's a cleaner way of writing it.

As of PHP 5.3, you can shorten ternary operations down to two expressions, like so:

$mycheck = $_POST['value'] ?: 0;

It means basically what you already have.

answered Jul 20, 2012 at 16:12

Palladium

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