How to handle efficiently Google Vision API Client Lib response? - php

Question

I'm new to Google Vision API Client Lib
I'm using Vision API Client Lib for PHP to detect text in images, this is my code:
<?php
require 'vendor/autoload.php';
use Google\Cloud\Vision\VisionClient;
function object_to_array($object) {
return (array) $object;
}
$vision = new VisionClient(
['keyFile' => json_decode(file_get_contents("smartcity-credentials.json"), true)]
);
$img = file_get_contents('img2.jpg');
$image=$vision->image($img,['DOCUMENT_TEXT_DETECTION']);
$result=$vision->annotate($image);
$res=object_to_array($result);
var_dump($res);
?>
All I need is using response as an array for handling, but $result returns something likes array of object/object ( sorry because I don't know much of OOP/Object)
Although i convert $result to array $res, but if I use foreach loop
foreach ($res as $key=>$value){
echo $value;
echo '<br>';
}
I get this
Catchable fatal error: Object of class Google\Cloud\Vision\Annotation\Document could not be converted to string
How do we get value (text detected) in above response for using ?.

Answer 1

You should use the methods fullText() and text() in order to access to the detected text, something like this:
$document = $annotation->fullText();
$text = $document->text();
See the specification of these classes Annotation and Document.

Answer 2

you cannot use $value of type Document as string with the echo.
use print_r($annotation); to see what you even get returned.
this document text detection example looks quite alike, notice the nested foreach loops there. also see the documentation:
use Google\Cloud\Vision\VisionClient;
$vision = new VisionClient();
$imageResource = fopen(__DIR__.'/assets/the-constitution.jpg', 'r');
$image = $vision->image($imageResource, ['DOCUMENT_TEXT_DETECTION']);
$annotation = $vision->annotate($image);
$document = $annotation->fullText();
$info = $document->info();
$pages = $document->pages();
$text = $document->text();
here's some more examples; in particular the detect_document_text.php.