JSON: Update base64 string using url JSON

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

The problem here is that the url does not return any response, and that causes the json_decode(...) to return a NULL value and file_get_contents(...) does not receive a valid file path. — Héctor M., Feb 14 '20 at 04:07
If the URL does not respond, the problem is not found in the code. Putting the URL in any browser expires the connection without any response. Can you tell me what is that URL? — Héctor M., Feb 14 '20 at 04:13
You should replace urlencode( ) with base64_encode( ) => https://www.php.net/manual/es/function.base64-encode.php — Héctor M., Feb 14 '20 at 04:20
that URL is the link to the web services. Like I said if the string is short. The successful update. But if the string is in base64. it will get the error. — Peter Sondak, Feb 14 '20 at 04:23
Can you try store session variable $_SESSION['imagebase64'] = 'base64code'; — vadivel a, Feb 14 '20 at 04:48

Igwe Kalu · Answer 1 · 2020-02-22T06:40:28.160

// ...
// 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";
}

?>

@lgwe Kalu. Thanks for your reply. Can you help me to edit my code above? Really need your help. Thanks — Peter Sondak, Feb 20 '20 at 01:13
I've made some adjustment to your code in my answer, hopefully that should get you going. — Igwe Kalu, Feb 22 '20 at 06:41
@PeterSondak, could you please accept this answer to help others find it? Thanks! — Igwe Kalu, Jul 11 '21 at 12:21

score -1 · Answer 2 · answered Feb 14 '20 at 04:31

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.

JSON: Update base64 string using url JSON

2 Answers2