Download Facebook file from the WhatsApp app on Meta Developers

[jeanp74]

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Hello, I am working on an integration with the WhatsApp app on Meta Developers for Facebook.

I am conducting tests, and when I send a message to the WhatsApp number of the app, it returns the ID that I can use to download that file. When I do it through the Postman app, it downloads the file correctly, but when I try to replicate it in PHP (since that's how the website works), the file does not download correctly, as if it were corrupted. I am doing it with cURL, and here’s the code I have:

<?php
date_default_timezone_set('America/Bogota');
header("Cache-control: no-cache");

// Your access token
$token = 'Token provided by Facebook';

// ID of the uploaded file (id_documento)
$id_documento = 'file id';

// URL to get the file information
$url = "https://graph.facebook.com/v19.0/$id_documento";

// Set up the request headers
$headers = [
    "Authorization: Bearer $token",
    "Content-Type: application/json"
];

// Initialize cURL to get the download URL and MIME type
$curl = curl_init();
curl_setopt($curl, CURLOPT_URL, $url);
curl_setopt($curl, CURLOPT_HTTPHEADER, $headers);
curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);

// Execute the request
$response = curl_exec($curl);

// Check if there are errors
if ($response === false) {
    $error = curl_error($curl);
    echo "Error: $error";
    die("ERROR SENDING THE URL");
}

// Close initial cURL
curl_close($curl);

$data = json_decode($response, true);

if ($data != '' && $data != NULL) {
    $download_url = $data['url'];
    $mime_type = $data['mime_type'];

    // MIME map to extension
    $mime_map = [
        'application/pdf' => 'pdf',
        'image/jpg' => 'jpg',
        'image/jpeg' => 'jpeg',
        'image/png' => 'png',
        'video/mp4' => 'mp4',
    ];

    $extension = isset($mime_map[$mime_type]) ? $mime_map[$mime_type] : 'bin';

    // Set up the request headers
    $headers = [
        "Authorization: Bearer $token"
    ];

    // Initialize cURL to download the file
    $curl_file = curl_init();
    curl_setopt($curl_file, CURLOPT_URL, $download_url);
    curl_setopt($curl_file, CURLOPT_HTTPHEADER, $headers); // Use the same header with the token
    curl_setopt($curl_file, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($curl_file, CURLOPT_HEADER, 0);
    curl_setopt($curl_file, CURLOPT_FOLLOWLOCATION, true);
    curl_setopt($curl_file, CURLOPT_SSL_VERIFYPEER, false); // Disable SSL verification if necessary
    curl_setopt($curl_file, CURLOPT_AUTOREFERER, true);

    // Execute the download request
    $file_data = curl_exec($curl_file);

    // Check for errors in the download
    if ($file_data === false) {
        $error = curl_error($curl_file);
        die("Download error: $error");
    }

    // Get the HTTP response code
    $httpCode = curl_getinfo($curl_file, CURLINFO_HTTP_CODE);

    // Check if the download was successful (HTTP code 200)
    if ($httpCode !== 200) {
        die('Error: Unable to download the file. HTTP Code: ' . $httpCode);
    }

    // Close cURL after download
    curl_close($curl_file);
    
    // Save the file on the server with the dynamic extension
    $file = "downloaded_file.$extension";

    // Set the HTTP headers for the file download
    header("Content-Description: File Transfer");
    header("Content-Type: $mime_type");
    header("Content-Disposition: attachment; filename=$file");
    header("Content-Transfer-Encoding: binary");
    header("Expires: 0");
    header("Cache-Control: must-revalidate");
    header("Pragma: public");
    header("Content-Length: " . strlen($file_data));

    // Output the file content
    echo $file_data;
}
?>

When the file downloads, it gives me an error message that says:

However, the file does have the correct size, and when I print the cURL response, it shows the following:

I have the browser updated and everything, but it still doesn't work.

Honestly, I’ve been programming for a year, and I am new to cURL, and I don’t understand why it’s failing.

[Mefamex]

Hi @jeanp74
I think, when downloading files with PHP cURL, several things can cause corruption. Network problems like intermittent connectivity or timeouts can interrupt the download, leaving you with an incomplete file. How you set up your cURL options is crucial too. Make sure you're using CURLOPT_FILE to write directly to a file, and avoid the deprecated CURLOPT_BINARYTRANSFER. Double-check that your script has the right file permissions and that you're opening and closing the file pointer correctly. The server can also be the culprit. If it sends back an error page instead of the file, or if it uses compression that cURL isn't handling, you'll get a corrupted file. Also, make sure you're treating binary and text files differently. Binary files need special handling, and even text files can have formatting problems if you're not careful. A .curlrc file with conflicting default options could also mess things up, so try ignoring it with -q if you suspect this. Finally, watch out for encoding issues. If the file's encoding doesn't match what you expect, it can lead to corruption.

[jeanp74]

Hi @Mefamex, I have already solved the problem. What happens is that Facebook queried these documents in such a way that it does not allow downloading from a browser. What I had to do was add a ```
user-agent

To summarize, I had to add the ```
user-agent
``` key in the headers so that Facebook would allow the file to be downloaded.

[Mefamex]

Hi @Mefamex, I have already solved the problem. What happens is that Facebook queried these documents in such a way that it does not allow downloading from a browser. What I had to do was add a ``` user-agent

To summarize, I had to add the ```
user-agent
``` key in the headers so that Facebook would allow the file to be downloaded.

Nice