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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About Clivant

Clivant a.k.a Chai Heng enjoys composing software and building systems to serve people. He owns techcoil.com and hopes that whatever he had written and built so far had benefited people.

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