PHP Strange NULL variable situation

Question

I'm having a tough time with this one, I have a class which populates an array.

Sometimes the array will not be populated and I want make an edge-case for when this happens however I can't seem to tell when its null! Here's the code:

$results_dev = $class->get_data_nologin("4a9d-4f41-9566-7705",$key,"Sensors");
    echo "something";
    print_r($results_dev);

    if(is_null($results_dev))
    {   
        echo "thisisNULL";
        $counter--;
    }

"something" does get echoed out, but when I print_r $results_dev, it prints "null" and the if statement never executes! I've also tried

if(!$results_dev)

and

if($results_dev == "null")

and

if($results_dev == null)

But it still doesn't execute whats in the if loop, how else could I check this?

BTW: my class curls an API and retrieves a JSON, however sometimes the URL is incorrect in curl so it returns null. What's even worse is after this I have:

if($results_dev['location'])
    {
        echo "data".$results_dev['location'];

And It executes even when its null! It prints "data" and absolutely nothing afterwards.

code for get_data_nologin:

    $url = 'https://api.url/'.$scf.'/'.$deviceid.'?key='.$apikey;
    $curl_handle = curl_init();
    curl_setopt($curl_handle, CURLOPT_URL, $url);
    curl_setopt($curl_handle, CURLOPT_SSL_VERIFYPEER, FALSE); 
    curl_setopt($curl_handle, CURLOPT_CONNECTTIMEOUT, 2);
    curl_setopt($curl_handle, CURLOPT_RETURNTRANSFER, 1);
    curl_setopt($curl_handle, CURLOPT_COOKIEJAR, $cookie_file_path);
    curl_setopt($curl_handle, CURLOPT_COOKIEFILE, $cookie_file_path);
    $buffer = curl_exec($curl_handle);
    curl_close($curl_handle);
    if (empty($buffer)) 
    {
        echo 'Something went wrong :(';
    } 
    else 
    {

            $decodedBuffer = json_decode($buffer, TRUE);

            return $decodedBuffer;

    }

If the result of the function call is actually the NULL value, your code should be working -- see ideone.com/hBYk5. — Daniel Vandersluis
– Daniel Vandersluis, Commented Sep 27, 2010 at 17:44
Could the json_decode perhaps be not sending a true NULL value? — Doug Molineux
– Doug Molineux, Commented Sep 27, 2010 at 17:46
According to its manual page: Returns the value encoded in json in appropriate PHP type. Values true, false and null (case-insensitive) are returned as TRUE, FALSE and NULL respectively. NULL is returned if the json cannot be decoded or if the encoded data is deeper than the recursion limit. — Daniel Vandersluis
– Daniel Vandersluis, Commented Sep 27, 2010 at 17:47
As Daniel says, it should work. Most likely there's just an error in the name of the variable (do you show E_NOTICE errors on your dev-server?), or you get a really unexpected result in json (the string 'null' for instance, possibly surrounded with xml/html tags you cannot see, but would explain why $results_dev['location'] works but seemingly displays no data). — Wrikken
– Wrikken, Commented Sep 27, 2010 at 17:48

Stewie · Accepted Answer · 2010-09-27 18:03:07Z

3

use isset($results_dev)

if(!isset($results_dev)){
 echo "thisisNULL";
        $counter--;

}

With new inputs this can be the solution:

if(strtolower($results_dev) == 'null'){ 
     echo "thisisNULL";
            $counter--;

}

edited Sep 27, 2010 at 18:03

answered Sep 27, 2010 at 17:38

Stewie

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6 Comments

Doug Molineux Over a year ago

Thank you for responding, isset($results_dev) isn't triggering anything either

Daniel Vandersluis Over a year ago

If $class->get_data_nologin in OP's code returns an actual NULL value, is_null should work just as well as isset...

Stewie Over a year ago

@Daniel : Correct !! @Pete: stupid question, but.. does it return null as a string ? try this gettype($results_dev) and see what you get

Stewie Over a year ago

OK .. then do this: if(strtolower(gettype($results_dev)) == 'null'){

Doug Molineux Over a year ago

Its not triggering anything, wouldn't that look like if(string == 'null')?

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