One of the most powerful tools a Microsoft 365 user has is the CLI for Microsoft 365. The command line allows any user to get a lot of things done in a fast way. There is no boundary to the number of things a seasoned user can do by merely using the CLI for Microsoft 365.

This script shows how to perform operations if a command is not covered by the CLI for Microsoft 365.

Right now, AttachmentFiles property associated with a SharePoint list item is not available in CLI for Microsoft 365, so we need to execute a separate query to /_api/web/lists/getByTitle('list-title')/items(item-id)/AttachmentFiles endpoint to get the item attachments.

To call AttachmentFiles endpoint, we must acquire an access token from the Microsoft identity platform. To do this we can use m365 util accesstoken get command and attach the access token with AttachmentFiles endpoint as shown in this script.

Prerequisites

• CLI for Microsoft 365
• SharePoint Online site with list item attachments

PowerShell Script

Function Get-ListAttachments() {
    param
    (
        [Parameter(Mandatory = $true)] [string] $AccessToken,
        [Parameter(Mandatory = $true)] [string] $SiteURL,
        [Parameter(Mandatory = $true)] [string] $ListTitle,
        [Parameter(Mandatory = $true)] [int] $ItemId
    )   
    Try {
        $ListItemAttachmentsEndPoint = "$($SiteURL)/_api/web/lists/getbytitle('$($ListTitle)')/items($($ItemId))/AttachmentFiles"
        $Header = @{
            "Authorization" = "Bearer $($AccessToken)"
            "Accept"        = "application/json; odata=verbose" 
            "Content-Type"  = "application/json "
        }
        $ListItemAttachments = Invoke-RestMethod -Uri $ListItemAttachmentsEndPoint -Headers $Header -Method Get  
        return $ListItemAttachments.d.results
    }
    Catch {
        throw "Error Getting List Item Attachments! $($_.Exception.Message)" 
    }
}
Function Download-ListAttachments() {
    param
    (
        [Parameter(Mandatory = $true)] [string] $TenantName,
        [Parameter(Mandatory = $true)] [string] $SiteURL,
        [Parameter(Mandatory = $true)] [string] $ListTitle,
        [Parameter(Mandatory = $true)] [string] $DownloadDirectory
    )   
    Try {

        #Get All Items from the List
        $ListItems = m365 spo listitem list --webUrl $SiteURL --title $ListTitle -o json | ConvertFrom-Json -AsHashtable
         
        #Iterate through each list item
        Foreach ($Item in $ListItems) {
            Try {
                Write-Output "Processing Item Id $($Item.Id)"

                # Right now AttachmentFiles property is not available in cli-microsoft365 so we need to execute a separate query to /_api/web/lists/getByTitle('list-title')/items(item-id)/AttachmentFiles to get the item attachments. 
                # AttachmentFiles endpoint requires access token 
                $AccessToken = m365 util accesstoken get --resource "https://$($TenantName).sharepoint.com" --new 

                #Get All attachments from the List Item
                $Attachments = Get-ListAttachments -AccessToken $AccessToken -SiteURL $SiteURL -ListTitle $ListTitle -ItemId $Item.Id

                If ($Attachments.Length -gt 0) {
                    #Create directory for each list item if it doesn't exist
                    $TargetDownloadDirectory = "$($DownloadDirectory)/$($Item.Id)"
                    If (!(Test-Path -path $TargetDownloadDirectory)) { New-Item $TargetDownloadDirectory -type Directory | Out-Null }

                    foreach ($Attachment in $Attachments) {
                        Try {
                            Write-Output "Downloading $($Attachment.FileName)"
                            $TargetFilePath = "$($TargetDownloadDirectory)/$($Attachment.FileName)"
                            #Download attachment
                            m365 spo file get --webUrl $SiteURL --url $Attachment.ServerRelativeUrl --asFile --path $TargetFilePath
                        }
                        Catch {
                            Write-Error "Error Downloading This Attachment! $($_.Exception.Message)" 
                        }
                    }
                }
                else {
                    Write-Warning "Attachments Not Found For This List Item!"
                }
            }
            Catch {
                Write-Error "Error Downloading This List Item Attachments! $($_.Exception.Message)"
            }
        }
    }
    Catch {
        Write-Error "Error Downloading List Attachments! $($_.Exception.Message)"
    }
}

#Set Parameters
$TenantName = "tenant-name"
$SiteRelativePath = "site-relative-path"
$ListTitle = "list-title"

$DownloadDirectory = "$($PSScriptRoot)/$($ListTitle)"
$SiteURL = "https://$($TenantName).sharepoint.com/$($SiteRelativePath)"

#Call the function to download list items attachments
Download-ListAttachments -TenantName $TenantName -SiteURL $SiteURL -ListTitle $ListTitle -DownloadDirectory $DownloadDirectory