imagecreatefromstring(): Data is not in a recognized format in - php

Question

Here is how I get my image:
$coverurl = 'https://api.someurl/api/v1/img/' . $somenumber . '/l';
//$iheaders contains: 'Content-type' => 'image/jpeg'
$iresponse = wp_remote_get($coverurl, $iheaders);
$img = $iresponse['body'];
$testimg = base64_encode($img);
When I echo $testimg with an img-tag, everything works fine.
echo '<img class="attachment-shop_single size-shop_single wp-post-image" src="data:image/jpeg;base64,'.$testimg.'" width="274" />';
Since I need to convert the string into a jpg and save it to my uploads folder, I tried to use imagecreatefromstring().
$imgx = imagecreatefromstring($testimg);
if ($imgx !== false) {
header('Content-Type: image/jpeg');
imagejpeg($imgx);
imagedestroy($imgx);
} else {
echo 'An error occurred.';
}
But I never get to the point of saving anything, because of the following warning:
Warning: imagecreatefromstring(): Data is not in a recognized format in /etc.
When I echo $testimg I get:
/9j/4AAQSkZJRgABAQAAAQABAAD ...Many number and characters.. Ggm2JUsEvfqnxAhGFDP/9k=
What must I do to make createimagefromstring work? Do I have to modify the $testimg string? Thanks for your interest.

Answer 1

The method imagecreatefromstring does not take a base_64 encoded string. Try this instead:
$imgx = imagecreatefromstring($img); // Contents of $iresponse['body']
You can see this in the topmost comment in the documentation page (linked above):
<?php
$data = 'iVBORw0KGgoAAAANSUhEUgAAABwAAAASCAMAAAB/2U7WAAAABl'
. 'BMVEUAAAD///+l2Z/dAAAASUlEQVR4XqWQUQoAIAxC2/0vXZDr'
. 'EX4IJTRkb7lobNUStXsB0jIXIAMSsQnWlsV+wULF4Avk9fLq2r'
. '8a5HSE35Q3eO2XP1A1wQkZSgETvDtKdQAAAABJRU5ErkJggg==';
$data = base64_decode($data);
$im = imagecreatefromstring($data);

Answer 2

After looking at the codex https://codex.wordpress.org/Function_Reference/wp_insert_attachment, I found the solution:
//get the image from internet
$coverurl = 'https://api.someurl/api/v1/img/' . $somenumber . '/l';
$iresponse = wp_remote_get($coverurl, $iheaders);
$img = $iresponse['body'];
$directory = "/".date('Y')."/".date('m')."/";
$wp_upload_dir = wp_upload_dir();
//encode $img as with html image tag
$imgdata = base64_encode($img);
$filename = "gtb_". $isbnraw.".jpg";
$fileurl = "../wp-content/uploads".$directory.$filename;
$filetype = wp_check_filetype( basename($fileurl), null);
file_put_contents($fileurl, $img);
$attachment = array(
'guid' => $wp_upload_dir['url'] . '/' . basename( $fileurl ),
'post_mime_type' => $filetype['type'],
'post_title' => preg_replace('/\.[^.]+$/', '', basename($fileurl)),
'post_content' => '',
'post_status' => 'inherit'
);
$attach_id = wp_insert_attachment($attachment, $fileurl, $post_id);
require_once('../wp-admin/includes/image.php');
// Generate the metadata for the attachment, and update the database record.
$attach_data = wp_generate_attachment_metadata($attach_id, $fileurl);
wp_update_attachment_metadata($attach_id, $attach_data);
set_post_thumbnail($post_id, $attach_id);
//add media_category
wp_set_object_terms($attach_id, $mediacat, 'media_category');
This converts a base64 into a jpg and imports it into Wordpress plus attaches it to the post/product. It seems to work well. Thanks for your interest.