JSON: Update base64 string using url JSON - php

Question

I'm new to JSON Code. I want to learn about the update function. Currently, I successfully can update data to the database. Below is the code.
<?php
require_once "../config/configPDO.php";
$photo_after = 'kk haha';
$report_id = 1;
$url = "http://172.20.0.45/TGWebService/TGWebService.asmx/ot_maintainReport?taskname=&reportStatus=&photoBefore=&photoAfter=". urlencode($photo_after) . "&reportID=$report_id";
$data = file_get_contents($url);
$json = json_decode($data);
$query = $json->otReportList;
if($query){
echo "Data Save!";
}else{
echo "Error!! Not Saved";
}
?>
the problem is, if the value of $photo_after is base64 string, which is too large string, it will give the error:
1) PHP Warning: file_get_contents.....
2) PHP Notice: Trying to get property 'otReportList' of non-object in C:
BUT
when I change the code to this,
<?php
require_once "../config/configPDO.php";
$photo_after = 'mama kk';
$report_id = 1;
$sql = "UPDATE ot_report SET photo_after ='$photo_after', time_photo_after = GETDATE(), ot_end = '20:30:00' WHERE report_id = '$report_id'";
$query = $conn->prepare($sql);
$query->execute();
if($query){
echo "Data Save!";
}else{
echo "Error!! Not Saved";
}
?>
The data will updated including when the value of $photo_after is in base 64 string.
Can I know what is the problem? Any solution to allow the base64 string update thru json link?
Thanks

Answer 1

// ...
// It's likely that the following line failed
$data = file_get_contents($url);
// ...
If the length of $url is more than 2048 bytes, that could cause file_get_contents($url) to fail. See What is the maximum length of a URL in different browsers?.
Consequent to such failure, you end up with a value of $json which is not an object. Ultimately, the property otReportList would not exist in $json hence the error: ...trying to get property 'otReportList' of non-object in C....
To surmount the URL length limitation, it would be best to embed the value of $photo_after in the request body. As requests made with GET method should not have a body, using POST method would be appropriate.
Below is a conceptual adjustment of your code to send the data with a POST method:
<?php
require_once "../config/configPDO.php";
# You must adapt backend behind this URL to be able to service the
# POST request
$url = "http://172.20.0.45/TGWebService/TGWebService.asmx/ot_maintainReport";
$report_id = 1;
$photo_after = 'very-long-base64-encoding-of-an-image';
$request_content = <<<CONTENT
{
"taskname": $taskname,
"report_id": $report_id,
"photoBefore": $photoBefore,
"photo_after": $photo_after,
"reportStatus": $reportStatus
}
CONTENT;
$request_content_length = strlen($request_content);
# Depending on your server configuration, you may need to set
# $request_headers as an associative array instead of a string.
$request_headers = <<<HEADERS
Content-type: application/json
Content-Length: $request_content_length
HEADERS;
$request_options = array(
'http' => array(
'method' => "POST",
'header' => $request_headers,
'content' => $request_content
)
);
$request_context = stream_context_create($request_options);
$data = file_get_contents($url, false, $request_context);
# The request may fail for whatever reason, you should handle that case.
if (!$data) {
throw new Exception('Request failed, data is invalid');
}
$json = json_decode($data);
$query = $json->otReportList;
if ($query) {
echo "Data Save!";
} else {
echo "Error!! Not Saved";
}
?>

Answer 2

sending a long GET URL is not a good practice. You need to use POST method with cURL. And your webservice should receive the data using post method.
Here's example sending post using PHP:
//
// A very simple PHP example that sends a HTTP POST to a remote site
//
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL,"http://www.example.com/tester.phtml");
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS,
"postvar1=value1&postvar2=value2&postvar3=value3");
// In real life you should use something like:
// curl_setopt($ch, CURLOPT_POSTFIELDS,
// http_build_query(array('postvar1' => 'value1')));
// Receive server response ...
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$server_output = curl_exec($ch);
curl_close ($ch);
// Further processing ...
if ($server_output == "OK") { ... } else { ... }
Sample code from: PHP + curl, HTTP POST sample code?
And all output from the webservice will put in the curl_exec() method and from there you can decode the replied json string.