Code Samples: php

Showing posts with label php. Show all posts

Sunday, December 17, 2023

Using JavaScript to Upload Large Files in Chunks as Parts and Avoid Server Limits

We know that PHP config files has the limit to upload files to server, you know that uploading large files can be a real pain. You have to find the loaded php.ini file, edit the upload_max_filesize and post_max_size settings, and hope that you never have to change servers and do all of this over again.





We will do some trick to upload very very large file to server without manipulate any configuration, does not matter how small the limit is. We actually will send files from browser chunk by chunk. Chunk can be as small as our demand. Suppose if our server accept max 1mb request limit, we will send 1mb per request and many more.





  This will include two parts (1) is to send files chunk by chunk from browser to server and the other part (2) is save file parts into single file. I will use PHP example at backend to save file into server.





So below is Javascript parts with description:


<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>File Upload Chunk</title>
</head>
<body>
    <div class="form">
        <input type="file" id="file"/>
        <button type="button" id="upload">Upload</button>
    </div>
    <div class="toast">
        <div id="toast"></div>
    </div>
    <script type="text/javascript">
        document.getElementById("upload").addEventListener("click", () => {
            let files = document.getElementById("file").files;
            if (files.length === 0) {
                alert("File required");
            }
            else {
                showToast("Uploading");
                doUploadFileChunk(files[0], 1);
            }
        });

        function doUploadFileChunk(file, chunk) {
            let chunkLimit = 1024 * 50; // Limit of file chunk send to server is 50 KB for test purpose

            // Blob from position
            let fromSlice = (chunk - 1) * chunkLimit;
            // Blob to position
            let nextSlice = fromSlice + chunkLimit - 1;
            // new FormData()
            let formData = new FormData();
            formData.append("file_number", chunk);
            formData.append("file_name", file.name);
            formData.append("file_part", file.slice(fromSlice, nextSlice + 1)); // Processing small part of file

            console.log(`Sending from ${fromSlice} to ${nextSlice} KB`);

            // Sending to server
            let xhr = new XMLHttpRequest();
            xhr.open("POST", "upload.php", true);
            xhr.setRequestHeader("Accept", "application/json");
            xhr.onreadystatechange = () => {
                if (xhr.readyState === 4) {
                    console.log("Status = " + xhr.status);
                    try {
                        let response = JSON.parse(xhr.responseText);
                        console.log(response);
                        if (response.uploaded) {
                            let percent = Math.floor((nextSlice / file.size) * 100);
                            if (nextSlice < file.size) {
                                showToast(`Uploading file - ${percent}% completed`);
                                setTimeout(() => {
                                    doUploadFileChunk(file, chunk + 1);
                                }, 200);
                            }
                            else {
                                showToast(`Upload completed, processing started`);
                            }
                        }
                        else {
                            alert("Failed to upload file");
                        }
                    }
                    catch (e) {
                        console.log("Complete = " + xhr.responseText);
                        console.log(e);
                        alert("Failed to upload file");
                    }
                }
            };
            xhr.send(formData);
        }

        function showToast(text) {
            document.getElementById("toast").innerHTML = text;
        }
    </script>
    <style type="text/css">
        div.form {
            padding: 20px;
        }
        div.toast {
            padding: 20px;
            background-color: green;
            color: white;
            font-size: 31px;
        }
    </style>
</body>
</html>



And respective PHP file is as below:


<?php
$output = ["uploaded" => true, "file" => $_FILES["file_part"]];

$uploadFile = sprintf("storage/%s", $_POST['file_name']);
if ($_POST["file_number"] == 1) {
    if (file_exists($uploadFile)) {
        unlink($uploadFile);
    }
}

$destination = fopen($uploadFile, "a+");
if (FALSE === $destination) die("Failed to open destination");

$handle = fopen($_FILES["file_part"]["tmp_name"], "rb");
if (FALSE === $handle) die("Failed to open blob");

$BUFFER_SIZE=1*1024*1024; // 1MB, bigger is faster
while( !feof($handle) ) {
    fwrite($destination, fread($handle, $BUFFER_SIZE) );
}
fclose($handle);
fclose($destination);

echo json_encode($output);

Tuesday, December 5, 2023

Streaming HTTP response in PHP - turn long-running process into realtime UI

Streaming is not a new concept, it is a data transfer technique which allows a web server to continuously send data to a client over a single HTTP connection that remains open indefinitely. In streaming response comes in chunk rather than sending them at once. In the traditional HTTP request / response cycle, a response is not transferred to the browser until it is fully prepared which makes users wait.

Output buffering allows to have output of PHP stored into an memory (i.e. buffer) instead of immediately transmitted, it is a mechanism in which instead of sending a response immediately we buffer it in memory so that we can send it at once when whole content is ready.

Each time using echo we are basically telling PHP to send a response to the browser, but since PHP has output buffering enabled by default that content gets buffered and not sent to the client. But we will tell PHP to send output immediately then appear rather keep them wait until execution completed.

Php script will be like below which will usually send content chunk by chunk:

<?php
// Making maximum execution time unlimited
set_time_limit(0);              

// Send content immediately to the browser on every statement that produces output
ob_implicit_flush(1);           

// Deletes the topmost output buffer and outputs all of its contents
ob_end_flush();                 

sleep(1);
echo "Stream 1";

sleep(2);
echo "Stream 2";

sleep(3);
echo "Stream 3";

exit;

Output buffers catch output given by the program. Each new output buffer is placed on the top of a stack of output buffers, and any output it provides will be caught by the buffer below it. The output control functions handle only the topmost buffer, so the topmost buffer must be removed in order to control the buffers below it.

✔ The ob_implicit_flush(1) enables implicit flushing which sends output directly to the browser as soon as it is produced.

✔ If you need more fine grained control then use flush() function. To send data even when buffers are not full and PHP code execution is not finished we can use ob_flush and flush. The flush() function requests the server to send it's currently buffered output to the browser

How to get and process the response in javascript

There is a simple example how we can do it with traditional xhr ( XMLHTTPRequest ) request

function doCallXHR() {
    let lastResponseLength = 0;
    let xhr = new XMLHttpRequest();
    xhr.open("POST", "/do", true);
    xhr.setRequestHeader("Content-Type", "application/json");
    xhr.setRequestHeader("Accept", "application/json");
    xhr.onprogress = (e:any) => {
        let response = e.currentTarget.response;
        let progressResponse = lastResponseLength > 0 ? response.substring(lastResponseLength) : response;
        lastResponseLength = response.length;
        console.log(new Date());
        console.log(progressResponse);
    };
    xhr.onreadystatechange = () => {
        if (xhr.readyState == 4) {
            console.log("Status = " + xhr.status);
            console.log("Complete = " + xhr.responseText);
        }
    };
    xhr.send();
}
doCallXHR();

Output is as below from browser console:

Tue Dec 05 2023 23:18:59 GMT+0600 (Bangladesh Standard Time)
Stream 1
Tue Dec 05 2023 23:19:01 GMT+0600 (Bangladesh Standard Time)
Stream 2
Tue Dec 05 2023 23:19:04 GMT+0600 (Bangladesh Standard Time)
Stream 3
Status = 200
Complete = Stream 1Stream 2Stream 3

xhr.onprogress: is the function called periodically with information until the XMLHttpRequest completely finishes

Few points to note​

✅ we are sending chunk response from server and in xhr onprogress getting every new response part merged with the previously received part.

✅ it is possible to load the response one at a time as server response is multiple parts & in a format one after another. We can do it by substracting previoud response string length and parsing with JSON.parse

What if any error / exception occur! how to react to that?​

That's easy.. catch the error & respond with a status that the front-end js script can react to

<?php
try {
    $response = $this->expensiveProcessing();
} catch(\Exception $e) {
    // Handle the exception
    echo json_encode([
        'success' => false, 
        'message' => $e->getCode() . ' - '. $e->getMessage(), 
        'progress' => 100
    ]);

    ob_end_flush();
    exit;
}

Configuration for Nginx​

You need to do few tweaking with nginx server before working with output buffering.

fastcgi_buffering off;

proxy_buffering off;

gzip off;
    
For whichever reason if you don't have access to nginx server configuration then from PHP code you can also achieve the same result via HTTP header
    
header('X-Accel-Buffering: no');

Sunday, October 8, 2023

PHP image output and browser caching

This post is for return image from server by PHP script and cache in browser to save on our bandwidth.




Below code will return image using PHP script

<?php

function image_function_cache($file_name) {
    $file = "WWW_ROOT/public/img/$file_name";
    if (!file_exists($file) || !is_file($file)) {
        echo "";
        exit;
    }

    $fileTime = filemtime($file);
    $headerTime = IfModifiedSince();

    // Will return 304 when image source not changed
    if (!is_null($headerTime) && (strtotime($headerTime) == $fileTime)) {
        header('Last-Modified: '.gmdate('D, d M Y H:i:s', $fileTime).' GMT', true, 304);
        exit;
    }
    session_cache_limiter('none');

    $type = 'image/png';
    header('Content-Type:'.$type);
    header('Content-Length: ' . filesize($file));
    header('Cache-control: max-age='.(60*60*24*365));
    header('Expires: '.gmdate(DATE_RFC1123,time()+60*60*24*365));
    header('Last-Modified: '.gmdate('D, d M Y H:i:s', $fileTime).' GMT', true, 200);
    readfile($file);
    exit;
}

function IfModifiedSince() {
    if (function_exists("apache_request_headers")) {
        if ($headers = apache_request_headers()) {
            if (isset($headers['If-Modified-Since'])) {
                return $headers['If-Modified-Since'];
            }
        }
    }
    if (isset($_SERVER['HTTP_IF_MODIFIED_SINCE'])) {
        return $_SERVER['HTTP_IF_MODIFIED_SINCE'];
    }
    return null;
}



Check below image, there are two request for an image, first request status is 200 and image returned, but 2nd call if you see Size column image returned from cache. All happened for above functionality:

How to Send files via POST with cURL and PHP (Example)

In this process cURL send file to any web server along with other params. Check it out below code:




  
Assuming that you're using PHP 5.5+, you need to use CURLFile for uploading your file:


<?php

$headers = array(
    'Authorization: Bearer Token Value',
    'Content-type: multipart/form-data'
);

$url = "https://example.com/api/v1/import/uploadfile";

$post_data = array(
    "file1" => new CURLFile("/var/www/files/file1.csv", 'text/csv', 'File1.csv'),
    "file2" => new CURLFile("/var/www/files/file1.pdf", 'application.pdf', 'File1.pdf'),
    "param1" => "Test"
);

$curl = curl_init();
curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
curl_setopt($curl, CURLOPT_VERBOSE, true);
curl_setopt($curl, CURLOPT_HEADER, false);
curl_setopt($curl, CURLOPT_POST, true);
curl_setopt($curl, CURLOPT_URL, $url);
curl_setopt($curl, CURLOPT_POSTFIELDS, $post_data);
curl_setopt($curl, CURLOPT_HTTPHEADER, $headers);
$response = curl_exec($curl);
$status = curl_getinfo($curl, CURLINFO_HTTP_CODE);
curl_close($curl); 

Saturday, September 16, 2023

Create CSV file containing UTF-8 characters in PHP and Javascript | Illegal Character \ufeff Problem

If you create or read a CSV file and the file contains some characters such as ü or ş, then you will find the characters are not displayed correctly in Excel. This is because the default coding of Excel is not UTF-8. To force Excel to use UTF-8, we need to add BOM (Byte Order Mark) in the beginning of the file.

<?php

// When reading csv file using PHP

// BOM as a string for comparison.

$bom = "\xef\xbb\xbf";

// Read file from beginning.

$fp = fopen($path, 'r');

// Progress file pointer and get first 3 characters to compare to the BOM string.

if (fgets($fp, 4) !== $bom) {

    // BOM not found - rewind pointer to start of file.

    rewind($fp);

}

// Read CSV into an array.

$lines = array();

while(!feof($fp) && ($line = fgetcsv($fp)) !== false) {

    $lines[] = $line;

}
// When writting to csv file
$fp = fopen($myFile, 'w');
fputs($fp, $bom =( chr(0xEF) . chr(0xBB) . chr(0xBF) ));
fputcsv($fp, $otherdata);
// Javascript
var csvFormattedDataTable = '';
csvFormattedDataTable += "\uFEFF";
csvFormattedDataTable += "other stuff";
var encodedUri = 'data:application/csv;charset=utf-8,' + encodeURIComponent(csvFormattedDataTable);
$(buttonName).attr("href", encodedUri);
$(buttonName).attr("download", 'table-data.csv');
$(buttonName).attr("target", '_blank');

Monday, January 9, 2023

Composer require runs out of memory. PHP Fatal error: Allowed memory size of 1610612736 bytes exhausted

To get the current memory_limit value, run: 
php -r "echo ini_get('memory_limit').PHP_EOL;"

  Try increasing the limit in your php.ini file (ex. C:\xampp\php\php.ini for Windows-like systems):
; Use -1 for unlimited or define an explicit value like 2G
memory_limit = -1

Or, you can increase the limit with a command-line argument:
php -d memory_limit=-1 composer.phar require hwi/oauth-bundle php-http/guzzle6-adapter php-http/httplug-bundle

Monday, December 26, 2022

PHP & MySQL PDO: PDO binding values for MySQL IN statement - Bind an array to an IN() condition?

The answer there was that, for a variable sized list in the in clause, you'll need to construct the query yourself.

Consider your array like:

$values = array(1, 2, 3, 4, 5);

$count = count($values);

$criteria = sprintf("?%s", str_repeat(",?", ($count ? $count - 1 : 0)));

$sql = sprintf("DELETE FROM table where column NOT IN(%s)", $criteria);

$pdo->sth = prepare($sql);
$pdo->sth->execute($values);

SQL should be: DELETE FROM table where column IN (?,?,?,?,?)

Sunday, December 25, 2022

Rollback or Commit with PDO transaction using PHP and MySQL - SELECT query with PDO - PDO with INSERT INTO through prepared statements

  A transaction should end with either a rollback() or a commit(), (only one of them).
In case you are using MySQL, make sure you are not using MyISAM engine for tables, as it doesn't support transactions. It usually support InnoDB.
Some databases, including MySQL, automatically issue an implicit COMMIT when a database definition language (DDL) statement such as DROP TABLE or CREATE TABLE is issued within a transaction. The implicit COMMIT will prevent you from rolling back any other changes within the transaction boundary.


<?php
class DB {
    public static function transactional($closure) {
        $dbh = null;
        try {
            $dbh = new PDO("mysql:host=HOST_NAME;dbname=DB_NAME", "DB_USER_NAME", "DB_USER_PASSWORD");

            /*** Set the PDO error mode to exception (will throw exception if any error occurred) ***/
            /*** Follow the link for more info: http://php.net/manual/en/pdo.setattribute.php ***/
            $dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
            $dbh->setAttribute(PDO::ATTR_ORACLE_NULLS, PDO::NULL_EMPTY_STRING);

            /*** Transaction block starting here ***/
            $dbh->beginTransaction();

            $closure($dbh);

            $dbh->commit();
        }
        catch(Throwable $ex) {
            $dbh->rollback();

            throw $ex;
        }
    }
}

DB::transactional(function (PDO $PDO) {
    $PDO->prepare("INSERT INTO records (`RegistrationID`) VALUES(:RegistrationID)")->execute(['RegistrationID' => 'RegistrationID 1']);
    $PDO->prepare("INSERT INTO records (`RegistrationID`) VALUES(:RegistrationID)")->execute(['RegistrationID' => 'RegistrationID 2']);

    // $PDO->query used to get results
    $result = $PDO->prepare("SELECT * FROM records WHERE `RegistrationID` LIKE :RegistrationID");
    $result->execute(['RegistrationID' => '%RegistrationID%']);
    echo "<pre>";
    print_r($result->fetchAll());
    echo "</pre>";

    Below line will throw an exception and data will not persist into database.
    To persist data into database, comment below line.
    $x = null + null * $PDO->dd();
});
Output be as follows:Array
(
    [0] => Array
        (
            [id] => 12
            [0] => 12
            [RegistrationID] => RegistrationID 1
            [1] => RegistrationID 1
        )

    [1] => Array
        (
            [id] => 13
            [0] => 13
            [RegistrationID] => RegistrationID 2
            [1] => RegistrationID 2
        )

)

Pages

Sunday, December 17, 2023

Tuesday, December 5, 2023

Sunday, October 8, 2023

Saturday, September 16, 2023

Monday, January 9, 2023

Monday, December 26, 2022

Sunday, December 25, 2022