Using PHP & curl to post an html form that includes a file

Question

I have a form like this:

<form method="POST" action="i.php" enctype="multipart/form-data">
 <input type="text" name="field1">
 <input type="text" name="field2">
 <input type="file" name="file">
 <input type="hidden" name="MAX_FILE_SIZE" value="100000">
 <input type="submit">
</form>

On the page I already have:

$URL = 'http://somewhere.com/catch.php';
$fields = array('field1'=>urlencode($_POST['field1'), 'field2'=>urlencode($_POST['field2'));

    foreach($fields as $key=>$value) { $fields_string  .= $key.'='.$value.'&'; };

    rtrim($fields_string,'&');
    $ch = curl_init();

    curl_setopt($ch,CURLOPT_URL,$URL);
    curl_setopt($ch,CURLOPT_POST,count($fields));
    curl_setopt($ch,CURLOPT_POSTFIELDS,$fields_string);

    $result = curl_exec($ch);

    curl_close($ch);

That works to post the field1 & 2 fields. Is it possible to include the file in that curl process somehow? How would I do that? I'm assuming I have to do more than just encode the file value.

So based on SimpleCoders' answer I updated to the following:

$URL = 'http://somewhere.com/catch.php';
$fields = array('field1'=>urlencode($_POST['field1'), 'field2'=>urlencode($_POST['field2'), 'files'=>'@'. $_FILES['file']['tmp_name']);

    foreach($fields as $key=>$value) { $fields_string  .= $key.'='.$value.'&'; };

    rtrim($fields_string,'&');
    $ch = curl_init();

    curl_setopt($ch,CURLOPT_URL,$URL);
    curl_setopt($ch,CURLOPT_POST, 1);
    curl_setopt($ch,CURLOPT_POSTFIELDS,$fields_string);

    $result = curl_exec($ch);

    curl_close($ch);

which posts OK but then my resulting $_FILES array on catch.php is empty. Accoring to Example #2 on http://www.php.net/manual/en/function.curl-setopt.php This should work.

I am doing this on two different domains...might that be a problem?

Answer 1

Found this by Googling: http://forums.devshed.com/php-development-5/php-curl-send-a-file-533233.html

Look specifically at the second post.

Answer 2

You need to follow SimpleCoders answer but then change your

$fields_string

to just

$fields.  

From http://www.php.net/manual/en/function.curl-setopt.php

Note: Passing an array to CURLOPT_POSTFIELDS will encode the data as multipart/form-data, while passing a URL-encoded string will encode the data as application/x-www-form-urlencoded.