Updating a list item via Invoke-RestMethod

Question

I am at my wits end with this one.

I am unable to modify an list item remotely via a REST request.

Can anyone see what I am doing wrong here?

I am getting at 403 Forbidden response from SharePoint Specifically.

{"error":{"code":"-2130575251, Microsoft.SharePoint.SPException","message":{"lang":"en-US","value":"The security validation for this page is invalid and might be corrupted. Please use your web browser's Back button to try your operation again."}}}

Code I am using:

#if($pass = $Host.ui.PromptForCredential("Sharepoint List Load","Enter your credentials","",""))
#{    $cred = New-Object System.Management.Automation.PSCredential ($pass)
#}else{write-host "Cancelling.";exit}
$digest = $null
$sUserName="MYUSERNAMEHERE" 
$sPassword="MYPASSWORDHERE"
$sSecPassword=ConvertTo-SecureString $sPassword -AsPlainText -Force        
$spCredentials = New-Object System.Management.Automation.PSCredential($sUserName, $sSecPassword)

$WebRMethod=[Microsoft.PowerShell.Commands.WebRequestMethod]::POST
$TargetItemURL="http://someSPhost.domain.com/sites/MYSITENAME/_api/web/lists/GetByTitle('TEST')/items(1)"

$digest = (Invoke-RestMethod -Method post -UseDefaultCredentials -uri "http://someSPhost.domain.com /_api/contextinfo").GetContextWebInformation.FormDigestValue

$header = @{}
$header.add("Accept",'application/json;odata=verbose')
$header.add("Content-Type",'application/json;odata=verbose')
$header.add("X-HTTP-Method",'MERGE')
$header.add("X-RequestDigest",$digest)
$header.add("IF-MATCH",'*')

$metadata = @{__metadata = @{type = "SP.Data.TESTListItem"}
            Title = "some new test here"
            }

$JsonMetadata = $metadata | ConvertTo-Json -Compress

Write-host "---------TargetITEM-----------"        
$TargetItemURL
Write-host "---------Header-----------"        
$header
Write-host "---------Metadata-----------"    
$metadata
$metadata.__metadata
$JsonMetadata
Write-host "--------------------"        

Invoke-RestMethod -Uri $TargetItemURL -Body $JsonMetadata -Headers $header -Method $WebRMethod -Credential $spCredentials -ContentType "application/json;odata=verbose" 

Answer 1

Well, it turns out it is possible. My new friend, and moderator in the Microsoft Forum posted this lovely example. And it works like a champ.

https://social.microsoft.com/Forums/en-US/e4c47435-6568-46b8-b1bc-5d61deecac85/updating-a-list-item-via-invokerestmethod?forum=sharepointdevelopment

$user = "domain\admin"
$pass = "xx"
$listName = "TEST"
$itemId=1
$url = "http://2013/sites/team"

### TOGGLE DEBUG MODE
$debug = $false

### DO NOT MODIFY
$headers = @{accept = "application/json; odata=verbose"}
$formDigest = $null
$secPass = ConvertTo-SecureString $pass -AsPlainText -Force
$cred = New-Object System.Management.Automation.PSCredential ($user, $secPass)

function SetFormDigest() {
    $response = PostRequest ("/_api/contextinfo") $null
    $formDigest = $response.d.GetContextWebInformation.FormDigestValue
    $headers.Add("X-RequestDigest", $formDigest);
    $headers.add("IF-MATCH",'*')
    $headers.add("X-HTTP-Method",'MERGE')    
    if ($debug) {
        Write-Host "Form Digest: " $formDigest
    }
}
function Request ($endpoint, $body, $method) {
    if ($debug) {
        Write-Host "Endpoint: $endpoint, Method: $method, Cred:" $cred.UserName -BackgroundColor Green -ForegroundColor Black
        Write-Host "Header Keys:" $headers.Keys -BackgroundColor DarkGreen -ForegroundColor Gray
        Write-Host "Header Values:" $headers.Values -BackgroundColor DarkGreen -ForegroundColor Gray
        Write-Host "Body:" $body -BackgroundColor DarkGreen -ForegroundColor Gray        
    }
    return Invoke-RestMethod -Uri ($url+$endpoint) -Headers $headers -Method $method -Body $body -Credential $cred -ContentType "application/json;odata=verbose"
}
function PostRequest ($endpoint, $body) {
     Write-Host "Body1:" $body -BackgroundColor DarkGreen -ForegroundColor Gray
    return Request $endpoint $body ([Microsoft.PowerShell.Commands.WebRequestMethod]::Post)
}
function UpdateListItem($listName, $itemId) {
    SetFormDigest
    $body = "{ '__metadata': { 'type': 'SP.Data."+$listName+"ListItem' }, Title: 'some new text here'}"
    $response = PostRequest ("/_api/web/lists/getbytitle('"+$listName+"')/items("+$itemId+")") $body
}

## Script Begin ##
UpdateListItem $listName $itemId