PHP cURL: upload file from form to remote API? - php

Question

I'm trying to upload a file on a form on my site, and then pass it on to a remote API.
This is my PHP:
$fields = array(
'file'=>$_FILES["mediaupload"],
'username'=>urlencode($_POST["username"]),
'password'=>urlencode($_POST["password"]),
'latitude'=>urlencode($_POST["latitude"]),
'longitude'=>urlencode($_POST["longitude"]),
);
$fields_string = http_build_query($fields);
$url = my_url;
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL,$url);
curl_setopt($ch,CURLOPT_POST,count($fields));
curl_setopt($ch,CURLOPT_POSTFIELDS,$fields_string);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
$response = curl_exec ($ch);
At the moment I keep getting error messages that the file could not be processed properly. The API expects all fields as POST strings except the file, which it expects in binary.
I know it's going to be tough to debug this for you guys without access to the remote API, but am I doing anything obviously wrong, or should this work?
Many thanks.

Answer 1

File upload using curl does not work like this. You need to first save the file locally using php's move_uploaded_file then get the path to file. In the fields add this,
$fields = array(
'file'=>"#/path/to/myfile.ext",
'username'=>urlencode($_POST["username"]),
'password'=>urlencode($_POST["password"]),
'latitude'=>urlencode($_POST["latitude"]),
'longitude'=>urlencode($_POST["longitude"]),
);
Also,
I'm not sure if fields array needs to be converted to string to be used as postfields. According to manual it can be an array() directly.
CURLOPT_POSTFIELDS The full data to
post in a HTTP "POST" operation. To
post a file, prepend a filename with #
and use the full path. The filetype
can be explicitly specified by
following the filename with the type
in the format ';type=mimetype'. This
parameter can either be passed as a
urlencoded string like
'para1=val1&para2=val2&...' or as an
array with the field name as key and
field data as value. If value is an
array, the Content-Type header will be
set to multipart/form-data. As of PHP
5.2.0, files thats passed to this option with the # prefix must be in
array form to work.