powershell invoke-restmethod multipart/form-data

It should be pretty straight forward. Taking from this answer:

$Uri = 'https://server/api/';
$Headers = @{'Auth_token'=$AUTH_TOKEN};
$FileContent = [IO.File]::ReadAllText('C:\test\test.test');
$Fields = @{'appInfo'='{"name": "test","description": "test"}';'uploadFile'=$FileContent};

Invoke-RestMethod -Uri $Uri -ContentType 'multipart/form-data' -Method Post -Headers $Headers -Body $Fields;

You may want to use [IO.File]::ReadAllBytes() if the file isn't a text file.

This also may not work well if you're uploading a huge file.

@Bacon-Bits answer didn't seem to work for me. My server rejected it with a potentially malformed form-data body :-(

I found this gist, and trimmed it up a bit for my purposes. Here's my end result:

$FilePath = 'c:\temp\temp.txt';
$URL = 'http://your.url.here';

$fileBytes = [System.IO.File]::ReadAllBytes($FilePath);
$fileEnc = [System.Text.Encoding]::GetEncoding('UTF-8').GetString($fileBytes);
$boundary = [System.Guid]::NewGuid().ToString(); 
$LF = "`r`n";

$bodyLines = ( 
    "--$boundary",
    "Content-Disposition: form-data; name=`"file`"; filename=`"temp.txt`"",
    "Content-Type: application/octet-stream$LF",
    $fileEnc,
    "--$boundary--$LF" 
) -join $LF

Invoke-RestMethod -Uri $URL -Method Post -ContentType "multipart/form-data; boundary=`"$boundary`"" -Body $bodyLines