stream-multipart-example.php

<?php
$stream = new GuzzleHttp\Psr7\MultipartStream([['name' => 'some-file', 'contents' => 'the contents']]);
$client = new GuzzleHttp\Client();
$r = $client->request('POST', 'http://httpbin.org/post', ['body' => $stream]);
$r->getBody()->getContents();
=> """
   {\n
     "args": {}, \n
     "data": "", \n
     "files": {}, \n
     "form": {\n
       "some-file": "the contents"\n
     }, \n
     "headers": {\n
       "Content-Length": "122", \n
       "Content-Type": "multipart/form-data; boundary=568daeba8d610", \n
       "Host": "httpbin.org", \n
       "User-Agent": "GuzzleHttp/6.1.1 curl/7.37.1 PHP/5.6.13"\n
     }, \n
     "json": null, \n
     "origin": "72.18.228.42", \n
     "url": "http://httpbin.org/post"\n
   }\n
   """
>>> 

for 'contents' you can just pass in a stream resource instead of a string.

As well as name and contents, there are other optional elements, such as filename and headers. The headers can be used to set Content-Type for a file, for example.

Not forgetting also that instantiating MultipartStream involves passing in multiple fields/parts, which can be a mix of text and streams.

Thanks Matthew, this is great stuff.

What I don't understand, is how your Content-Type is being set by Guzzle. I am finding Guzzle, using PSR-7 messages does not detect the content type automatically, and does not set the Content-Type header. I am having to explicitly set the Content-Type header, which means also defining my own multipart boundary for this (Guzzle can give you the boundary it defines, but that is less portable). Are you using a stable Guzzle, or bleeding-edge dev?