PHP: checking key value is not empty

Question

I wrote a small function to check the required fields of a form, are not empty. The function accepts two arguments, 1st is an array with all values from $_POST superglobal. 2nd is the required fields array which I populate.

Have a look:

public $errors = array();

public function validate_fields($fields_array, $required_fields) 
{
    foreach ($required_fields as $key => $value)
    {
        if (array_key_exists($key, $fields_array)) 
        {
            # If key exists in $fields_array
            # check that the key value inside $fields_array is set & isn't empty
            # if it's empty, populate with an error
            if(empty($fields_array[$key][$value]))
            {
                $this->errors[] = "{$key} is empty but in fields_array";
            }
        }
        else 
        {
            # Key does not exists in $fields_array
            # Did someone temper with my html ?
            $this->errors[] = "{$key} is not in fields_array";
        }
    }
    return (empty($this->errors)) ? true : false;
}

The issue I'm having seems to be related to "if(empty($fields_array[$key][$value]))" statement. my goal is to check that $fields_array key value is not empty based on $required_fields key. I'm sure the statement I'm using is off. If you see anything that you think can be written better, please let me know, as I am new to php. Appreciate the help.

kufudo · Accepted Answer · 2013-02-13 00:23:42Z

5

I think what you're trying to do is:

if(empty($fields_array[$key])) {
    //this means value does not exist or is FALSE
}

If you also want to check for empty-strings or white-space only, then you need something more than just empty. E.g.

if(empty($fields_array[$key]) || !trim($fields_array[$key]))         {
    //this means key exists but value is null or empty string or whitespace only
}

answered Feb 13, 2013 at 0:23

kufudo

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3 Comments

elad.chen Over a year ago

Hi Richard, Thanks! I was unaware that empty is returning false on white spaces. Thanks again. By the way, this is how I populate the required fields array: $required_fields = array("email" => "", "email_confirm" => ""); is there a faster approach to setting an array with just the key instead of defining key + empty value ?

kufudo Over a year ago

$required_fields = array_fill_keys(array("email", "email_confirm","..."), "");

elad.chen Over a year ago

Thanks, that cleans it up a bit.

Community · Accepted Answer · 2023-11-17 20:08:53Z

4

Do note that the above answers will only work for indexed arrays in >PHP 5.4. If you have an associative array you have to use isset instead of empty:

if(isset($fields_array[$key]) && trim($fields_array[$key]) != '')

See https://www.php.net/manual/en/function.empty.php, example #2

edited Nov 17, 2023 at 20:08

CommunityBot

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answered Jun 10, 2014 at 12:51

Maarten00

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Comments

shapeshifter · Accepted Answer · 2013-02-13 00:34:51Z

2

You don't need to select the value as an index just key. Where $fields_array[$key] = $value;

if(empty($fields_array[$key]) && trim($fields_array[$key]) != '')

edited Feb 13, 2013 at 0:34

answered Feb 13, 2013 at 0:17

shapeshifter

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4 Comments

elad.chen Over a year ago

I see you added a few more conditions then Richard, wouldn't using empty and !trim cover everything I want to avoid? (any empty string or white spaces)

kufudo Over a year ago

Just be careful with empty(), it treats things like 0 or "0" as 'empty', which may not be what you want in some cases. See the comments in php.net/manual/en/function.empty.php for more details. It's probably better to explicitly check for the conditions that you want.

elad.chen Over a year ago

I can't think of any reason I would expect users to input 0, "0", or even "-0" in a form. Even though I have 2 radio buttons for gender during register, I'll assign them to 1 & 2 in the db. If my logic is wrong, correct me :)

shapeshifter Over a year ago

I would assign them to male/female or m/f. Its easily readable even when looking at the db without any context.

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