PHP - warning - Undefined property: stdClass - fix?

I get this warning in my error logs and wanted to know how to correct this issues in my code.

Warning: PHP Notice: Undefined property: stdClass::$records in script.php on line 440

Some Code:

// Parse object to get account id's
// The response doesn't have the records attribute sometimes.
$role_arr = getRole($response->records);  // Line 440 

Response if records exists

stdClass Object
(
    [done] => 1
    [queryLocator] =>
    [records] => Array
        (
            [0] => stdClass Object
                (
                    [type] => User
                    [Id] =>
                    [any] => stdClass Object
                        (
                            [type] => My Role
                            [Id] =>
                            [any] => <sf:Name>My Name</sf:Name>
                        )

                )

        )

    [size] => 1
)

Response if records does not exist

stdClass Object
(
    [done] => 1
    [queryLocator] =>
    [size] => 0
)

I was thinking something like array_key_exists() functionality but for objects, anything? or am I going about this the wrong way?

if(isset($response->records))
    print "we've got records!";

In this case, I would use:

if (!empty($response->records)) {
 // do something
}

You won't get any ugly notices if the property doesn't exist, and you'll know you've actually got some records to work with, ie. $response->records is not an empty array, NULL, FALSE, or any other empty values.

isset() is fine for top level, but empty() is much more useful to find whether nested values are set. Eg:

if(isset($json['foo'] && isset($json['foo']['bar'])) {
    $value = $json['foo']['bar']
}

Or:

if (!empty($json['foo']['bar']) {
    $value = $json['foo']['bar']
}

You can use property_exists
http://www.php.net/manual/en/function.property-exists.php

If you want to use property_exists, you'll need to get the name of the class with get_class()

In this case it would be :

 if( property_exists( get_class($response), 'records' ) ){
       $role_arr = getRole($response->records);
 }
 else
 {
       ...
 }

Error control operator

In case the warning is expected you can use the error control operator @ to suppress thrown messages.

$role_arr = getRole(@$response->records);

While this reduces clutter in your code you should use it with caution as it may make debugging future errors harder. An example where using @ may be useful is when creating an object from user input and running it through a validation method before using it in further logic.

---

Null Coalesce Operator

Another alternative is using the isset_ternary operator ??. This allows you to avoid warnings and assign default value in a short one line fashion.

$role_arr = getRole($response->records ?? null);

The response itself seems to have the size of the records. You can use that to check if records exist. Something like:

if($response->size > 0){
    $role_arr = getRole($response->records);
}

If think this will work:

if(sizeof($response->records)>0)
$role_arr = getRole($response->records);

newly defined proprties included too.