How to send multipart/form-data with PowerShell Invoke-RestMethod
The accepted answer won't do a multipart/form-data
request, but rather a application/x-www-form-urlencoded
request forcing the Content-Type
header to a value that the body does not contain.
One way to send a multipart/form-data
formatted request with PowerShell is:
$ErrorActionPreference = 'Stop'
$fieldName = 'file'
$filePath = 'C:\Temp\test.pdf'
$url = 'http://posttestserver.com/post.php'
Try {
Add-Type -AssemblyName 'System.Net.Http'
$client = New-Object System.Net.Http.HttpClient
$content = New-Object System.Net.Http.MultipartFormDataContent
$fileStream = [System.IO.File]::OpenRead($filePath)
$fileName = [System.IO.Path]::GetFileName($filePath)
$fileContent = New-Object System.Net.Http.StreamContent($fileStream)
$content.Add($fileContent, $fieldName, $fileName)
$result = $client.PostAsync($url, $content).Result
$result.EnsureSuccessStatusCode()
}
Catch {
Write-Error $_
exit 1
}
Finally {
if ($client -ne $null) { $client.Dispose() }
if ($content -ne $null) { $content.Dispose() }
if ($fileStream -ne $null) { $fileStream.Dispose() }
if ($fileContent -ne $null) { $fileContent.Dispose() }
}
The problem here was what the API required some additional parameters. Initial request required some parameters to accept raw content and specify filename/size. After setting that and getting back proper link to submit, I was able to use:
Invoke-RestMethod -Uri $uri -Method Post -InFile $filePath -ContentType "multipart/form-data"