Knowledge Base

For the times when you have to be icky and use it, here you go. Also this method uses the application server itself and the admin credential, because I was unable to authenticate using claims auth only from Powershell for using the client-side functions.

#    Upload-Directory-To-Sharepoint is adapted from https://stackoverflow.com/questions/20237294/upload-file-to-sharepoint-document-library-using-powershell
#    with some examples from https://www.sharepointdiary.com/2016/08/sharepoint-online-create-folder-using-powershell.html

Function Upload-Directory-To-Sharepoint {
    [CmdletBinding(SupportsShouldProcess)]
    Param(
        [Parameter(Mandatory = $False)][string]$ParentDirectory = ".",
        [Parameter(Mandatory = $False)][string]$SPSite = "https://sp.example.com/admin/test",
        [Parameter(Mandatory = $False)][string]$Library = "Documents"
    )
    $web = Get-SPWeb -Identity $SPSite

    If ($web) {
        try {
            $list = $web.Lists.TryGetList($Library)
            # Change to the requested dir, so the relative paths all start with "." which can be easily cleaned up.
            Set-Location $ParentDirectory
            $files = Get-ChildItem -Path "." -Force -Recurse
            ForEach ($dir in $files | ? { $_.PSIsContainer } ) {
                # and we depend on them being ordered from parent directory down to child directories.
                $RelativeName = (($dir | Resolve-Path -Relative ) -Replace "^\.\\" ) -Replace "\\","/"
                $newDir = "$($list.RootFolder.ServerRelativePath)/$($RelativeName)"
                If ($PsCmdlet.ShouldProcess("Mkdir $($SPSite)$($newDir)")) { $results = $web.Folders.Add($newDir) ; }
            }
            ForEach ($file in $files | ? { !($_.PSIsContainer) -And $_.Name -ne "Thumbs.db" } ) {
                $RelativeName = (($file | Resolve-Path -Relative ) -Replace "^\.\\" ) -Replace "\\","/"
                $newFile = "$($list.RootFolder.Path)/$($RelativeName)"
                $newFileUrl = "$($SPSite)/$($newFile)"
                $stream = $file.OpenRead()
                If ($PSCmdlet.ShouldProcess("Upload $($newFileUrl)")) {
                    $done = $list.RootFolder.Files.Add("$($newFile)", $stream, $true)
                    Write-Host """$($SPSite)$($done.ServerRelativePath)"" Uploaded into the Site"    
                }
            }
        }
        catch {
            $ErrorMessage = $_.Exception.Message
            Write-Error $ErrorMessage
        }
    }

    else { Write-Host "Site Doesn't exist" }
    $list.Update();
}