How to receive HTTP post data and a file from a C# program using PHP

Some time ago, I wrote a post on how to send some data and a file from C#, via HTTP post, to a PHP script. I called that script GetPostRequest.php.

This post explains the internals of the script in handling the data received from the C# program.

Note that we can also present a form to our favourite browser to submit the same kind of data to GetPostRequest.php.

Accessing the data received from the C# / HTTP client in PHP

Recall that we had sent the following data to GetPostRequest.php with the following names (keys):

• myFileDescription
• myFile

Some text that describes the file will be associated with the myFileDescription key, while data related with the uploaded file will be associated with the myFile key.

Before I proceed to handle the data, I first create a conditional to test whether the two pieces of data are successfully detected by my PHP engine:

<?php
if (isset($_POST['myFileDescription']) && isset($_FILES['myFile']) ) {
    handlePostDataFromClient();
}
?>

The text data should be available in the $_POST variable, via the key myFileDescription, while the data related to the uploaded file in the $_FILES variable. I test for their existence with the isset function.

When the text data and file upload data are available, my script will proceed to call the code>handlePostDataFromClient function to handle them.

Handling the text data and file upload data from the client

<?php
function handlePostDataFromClient() {

    $fileDescription = $_POST['myFileDescription'];
    $filePath = handleFileUploadData();
    if ($filePath != NULL) {
        // saveDetailsToDatabase($fileDescription, $fileDescription);
    }
    else {
	header('HTTP/1.0 500 Internal Server Error');
    }
}
?>

Inside the handlePostDataFromClient function, I save the text data in a variable and call the handleFileUploadData function to handle the file upload.

When I am able to receive a file path from the handleFileUploadData function, I proceed to save the file description and file path to the database. If I receive a NULL from the function, I will return a HTTP 500 internal server error back to the C# client.

Details of the $_FILES['myFile']

Prior to coding handleFileUploadData, I first issue a call to print_r on $_FILES['myFile']. With that, I got the following when the HTTP post was performed successfully by the client:

Array
(
    [name] =>_MG_0867.JPG
    [type] =>image/jpeg
    [tmp_name] =>G:\Windows\Temp\php2E9F.tmp
    [error] => 0
    [size] => 6444620
)

After I got a glimpse of the $_FILES['myFile'] array, I proceeded to code the handleFileUploadData function:

<?php
function handleFileUploadData() {
	
    $success = ($_FILES['myFile']['error'] == 0); 
    if ($success) {
        $filePath = 'G:\\uploadedFiles\\' . time() . $_FILES['myFile']['name'];
 	$success = copy($_FILES['myFile']['tmp_name'], $filePath);
    }

    if ($success) {
        return $filePath;
    }
    else {
	return NULL;
    }
}
?>

I first check whether the PHP engine can successfully create the file from the HTTP request received from my C# client and make it available at some temporary folder on my folder. If it is successful in doing so, $_FILES['myFile']['error'] will contain 0.

I then derive a destination file path for copying the file from the temporary folder to a permanent location. I derive the destination file path with the uploaded file name, the current timestamp value and the folder where I want to save the file into. The uploaded file name is available in the $_FILES['myFile']['name'] variable.

I then proceed to perform the file copying by issuing a call to the copy function, passing it $_FILES['myFile']['tmp_name'] and the $filePath variable. The return value of the copy function will allow me to know if the copying is successful.

If the copying of the file is successful, I return the destination file path; if not, I return a NULL back to the caller.

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