PHP: Validation for required field

Question

I want to validate a field which is required. I am using following condition to check whether the field is not empty:

isset($value) && !empty($value)

But if I write 0 in the fields, it will still say the field is required. The empty() function considers 0 as an empty value as told in PHP manual but what else should I do? I have tried writing many conditions but they didn't work as expected.

I saw user contributions and found:

empty($var) && !is_bool($var)

I tried adding it to my condition like this but didn't work:

isset($value) && !empty($value) && is_bool($value)

What's actually saved in the $value when you var_dump it? — Johannes Klauß
– Johannes Klauß, Commented Aug 5, 2014 at 14:39
@ParagTyagi I'm making my own premium validation class. There isn't one value, I'm writing a single condition for integer type values and string type values. — Muhammed Talha Akbar
– Muhammed Talha Akbar, Commented Aug 5, 2014 at 14:42
Just a sidenote, this expression is redundant: isset($value) && !empty($value). empty() also checks if the variable is set, so there's no need to do a isset() check. — Vlad Cazacu
– Vlad Cazacu, Commented Aug 5, 2014 at 14:43
@VladCazacu isset checks whether variable is set & is not null while empty checks that variables is not null. — Muhammed Talha Akbar
– Muhammed Talha Akbar, Commented Aug 5, 2014 at 14:45

Parag Tyagi · Accepted Answer · 2014-08-05 15:08:00Z

1

Try below code:

$value = 0;

if(isset($value) && $value !== "")
{
    echo "Field not required";
}
else
{
    echo "Field required";
}

Output:

Field not required

Demo:

http://3v4l.org/JWJbj

Explanation:

The integer 0 is truthy. It means that anything that checks it in a boolean'ish manner will treat it as false. In particular, !empty($value) will evaluate to false, so is_numeric would never even get a chance to fail.

Short version: empty is too wishy-washy in this case. Check for null and '' explicitly (with data-type hence used !==).

edited Aug 5, 2014 at 15:08

answered Aug 5, 2014 at 14:48

Parag Tyagi

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Comments

Martin Müller · Accepted Answer · 2014-08-05 14:40:52Z

0

You can't check for empty. Basically you can only stick to the isset test.

If a field in the form was not filled this variable field will not be inside the $_POST superglobal and isset will return false. If the user typed 0 the variable name will exist inside $_POST isset will return true.

answered Aug 5, 2014 at 14:40

Martin Müller

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Comments

twicejr · Accepted Answer · 2014-08-05 14:41:15Z

0

I would do it as following:

function emptyTextValue($value)
{
    return trim((string) $value) !== '';
}

answered Aug 5, 2014 at 14:41

twicejr

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Comments

Naktibalda · Accepted Answer · 2014-08-05 14:42:04Z

0

You know that all you get is a string, so you don't need full functionality of empty() function:

isset($_POST['yourFieldName']) && $_POST['yourFieldName'] !== ''

answered Aug 5, 2014 at 14:42

Naktibalda

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1 Comment

user399666 Over a year ago

Be wary of whitespaces.

caRameL · Accepted Answer · 2014-08-05 14:42:17Z

0

You can replace the empty function by :

$value !== ""

If it's not exactly empty, then it will validate the condition.

answered Aug 5, 2014 at 14:42

caRameL

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Comments

Travis Weston · Accepted Answer · 2014-08-05 14:44:40Z

0

What I've done for my test is convert the empty check to a strlen check. Because PHP is so friendly, you can run a string comparison on the value. A value of null will return a 0 length string, while a value of 0 will return a length of 1. So what I've done is this:

if(isset($val) && strlen($val) > 0){
    // Do stuff
}

answered Aug 5, 2014 at 14:44

Travis Weston

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Comments

user3524542 · Accepted Answer · 2014-08-05 14:56:57Z

0

Try

isset($value) && $value != ''

answered Aug 5, 2014 at 14:56

user3524542

Comments

Muhammed Talha Akbar · Accepted Answer · 2014-08-06 11:52:05Z

0

I have found a nice condition by myself.

$value === 0 || $value === "0" ? isset($value) : isset($value) && !empty($value)

This works perfectly for every case.

answered Aug 6, 2014 at 11:52

Muhammed Talha Akbar

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Comments

slevy1 · Accepted Answer · 2014-11-06 23:03:03Z

0

I would check to be sure that the form had been submitted and then trim the field 'msg' in case there were any white space chars, i.e. newlines, carriage returns, tabs, spaces and then test that result to make sure it's not the empty string as follows:

<?php
if ( isset($_POST['msg']) && trim($_POST['msg']) !== '') {

    // other code

}

answered Nov 6, 2014 at 23:03

slevy1

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