Getting SOAP response in PHP even if value is not set - php

Question

I don't work with PHP very often, at least not at this level, so I need some help. I have a SOAP response in PHP that turns into an Object:
stdClass Object
(
[Food_Document] => stdClass Object
(
[Food_Type] => Fruit
[Food_Serial] => 923490123
[Food_Name] => Apple
[Food_PictureName] => rotten_apple.jpg
[Food_PictureData] => sdlkff90sd9f90af9903r90wegf90asdtlj34kljtklsmdgkqwe4otksgk
)
)
What I need is the data from Food_PictureName and Food_PictureData, but it explodes with a warning every time I try to access it if it doesn't exist. Some objects will contain Food_PictureName and Food_PictureData, but not all of the time. Sometimes, only one or the other will exist, or neither. Basically, "0 or more times."
Here's the code I'm using:
function get_food_photo($serial)
{
$soap = new SoapClient("WSDL_LINK", array('trace' => true));
$params = new StdClass;
$params->serialNumber = $serial; // or whatever serial number you choose
$res = $soap->GetFoodDocuments($params);
$res = $res->GetFoodDocumentsResult;
$thumbnail_data = $res->FoodDocument[0]->Food_PictureData;
$ext = str_replace('.', '', $res->FoodDocument[0]->Food_PictureExtension);
return '<img src="data:image/'.$ext.';base64,'.$thumbnail_data.'"/>';
}
Now, accessing this data and displaying it DOES work if the Food_PictureData property is not null or empty, but otherwise, it will generate a warning every time: Fatal error: Cannot use object of type stdClass as array
I have tried the following: isset(), empty(), property_exists(), __isset(), strlen(), and some others.
How do I get this data without throwing an exception if it doesn't exist?

Answer 1

Rewrite the function as
function get_food_photo($serial)
{
$soap = new SoapClient("WSDL_LINK", array('trace' => true));
$params = new StdClass;
$params->serialNumber = $serial; // or whatever serial number you choose
$res = $soap->GetFoodDocuments($params);
$res = $res->GetFoodDocumentsResult;
if (is_array($res->FoodDocument)) {
$document = $res->FoodDocument[0];
} else {
$document = $res->FoodDocument;
}
if (property_exists($document, 'Food_PictureData')) {
$thumbnail_data = $document->Food_PictureData;
} else {
$thumbnail_data = '';
}
if (property_exists($document, 'Food_PictureExtension')) {
$ext = str_replace('.', '', $document->Food_PictureExtension);
} else {
$ext = '';
}
return '<img src="data:image/'.$ext.';base64,'.$thumbnail_data.'"/>';
}