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Last active November 16, 2022 16:56
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PowerShell V3 Multipart/formdata example with REST-API (Invoke-RestMethod)
function Import-Portatour {
param (
[parameter(Mandatory=$True,Position=1)] [ValidateScript({ Test-Path -PathType Leaf $_ })] [String] $FilePath,
[parameter(Mandatory=$False,Position=2)] [System.URI] $ResultURL
$CODEPAGE = "iso-8859-1" # alternatives are ASCII, UTF-8
# We have a REST-Endpoint
# Testing
$userEmail = ""
# Read file byte-by-byte
$fileBin = [System.IO.File]::ReadAllBytes($FilePath)
# Convert byte-array to string
$enc = [System.Text.Encoding]::GetEncoding($CODEPAGE)
$fileEnc = $enc.GetString($fileBin)
# Read a second hardcoded file which we want to upload through the API call
$importConfigFileEnc = $enc.GetString([System.IO.File]::ReadAllBytes("C:\Users\xyz\Documents\WindowsPowerShell\portatour.importcfg"))
# Create Object for Credentials
$user = "Username"
$pass = "Passw0rd"
$secpasswd = ConvertTo-SecureString $pass -AsPlainText -Force
$cred = New-Object System.Management.Automation.PSCredential ($user, $secpasswd)
# We need a boundary (something random() will do best)
$boundary = [System.Guid]::NewGuid().ToString()
# Linefeed character
$LF = "`r`n"
# Build up URI for the API-call
$uri = $RESTURL + "?userEmail=$userEmail&mode=UpdateOrInsert"
# Build Body for our form-data manually since PS does not support multipart/form-data out of the box
$bodyLines = (
"Content-Disposition: form-data; name=`"file`"; filename=`"Import.xlsx`"",
"Content-Type: application/octet-stream$LF",
"Content-Disposition: form-data; name=`"importConfig`"; filename=`"portatour.importcfg`"",
"Content-Type: application/octet-stream$LF",
) -join $LF
try {
# Submit form-data with Invoke-RestMethod-Cmdlet
Invoke-RestMethod -Uri $uri -Method Post -ContentType "multipart/form-data; boundary=`"$boundary`"" -Body $bodyLines -Credential $cred
# In case of emergency...
catch [System.Net.WebException] {
Write-Error( "REST-API-Call failed for '$URL': $_" )
throw $_
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Shaimaaiti commented Jul 2, 2017

really thanks, that helps me more

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dmichine commented Sep 5, 2017

Thanks, was of great help. However I did have an issue around the boundary in the header

Invoke-RestMethod -Uri $uri -Method Post -ContentType "multipart/form-data; boundary="$boundary""

I've had to remove the quotes around $boundary for it to work

Invoke-RestMethod -Uri $uri -Method POST -ContentType "multipart/form-data; boundary=$boundary"

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Thanks for sharing this gist, it definitely helped me out. This is what I came up with

   $file = "c:\file.txt"

    $fileName = Split-Path $File 
    $boundary = [guid]::NewGuid().ToString()

    $fileBin = [System.IO.File]::ReadAllBytes($File)

    $enc = [System.Text.Encoding]::GetEncoding("iso-8859-1")

    $fileEnc = $enc.GetString($fileBin)

    $bodyLines = @(


        "Content-Disposition: form-data; name=`"file`"; filename=`"$filename`"",

        "Content-Type: application/octet-stream$LF",



        "Content-Disposition: form-data; name=`"importConfig`"; filename=`"portatour.importcfg`"",

        "Content-Type: application/octet-stream$LF",



    ) -join $LF
      $Headers = @{
            'Authorization' = $LoginToken
    $params = @{
        Uri         = $Uri
        Body        = $bodyLines
        Method      = 'Post'
        Headers     = $headers
        ContentType = "multipart/form-data; boundary=$boundary"
    Invoke-RestMethod @params


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I still having problem with file upload, can anyone try to help me, i got this
$CurlExecutable = "C:\Delphix\curl.exe"
$CurlArguments = '-l',
'--header', """content-type: multipart/form-data""",
'--header', """Authorization: ab2aac30-91b3-4790-8fda-80970dbadf33""",
'--form', "fileFormat=@e:\Tools\Powershell\Delphix\Masking\FileFormats\BS_REC00002_CSV.FF",
'--form', "fileFormatType=DELIMITED" ,

@(& $CurlExecutable @CurlArguments)

And thats Work, but i would like to convert it to invoke-restmethod (to get rid of curl)

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