Change the field order in a content type by PowerShell. As parameters, we need the name of the content type and the internal name of the field to reorder, and when the Mode parameter is set to Position the zero based number of the new position of the field. The script uses Load-CSOMProperties, a function implemented in the PBSPOPS module. When t…

ReorderContentTypeFields.ps1

param (
   	[Parameter(Mandatory=$true)]
    [string]$ContentType,
   	[Parameter(Mandatory=$true)]
    [string]$FieldName,
    [ValidateSet("First", "Last", "Position")]
    [string]$Mode,
    [string]$NewPosition
)

function SetContentTypeFieldOrder
{
    param (
    	[Parameter(Mandatory=$true)]
        [string]$ContentType,
    	[Parameter(Mandatory=$true)]
        [string]$FieldName,
        [ValidateSet("First", "Last", "Position")]
        [string]$Mode,
        [int]$NewPosition
    )

    $ct = Get-PnPContentType -Identity $ContentType -ErrorAction SilentlyContinue

    if ($ct -eq $null)
    {
        Write-Host -ForegroundColor Red "Content Type $ContentType could not be found."
    }
    else
    {
        Load-CSOMProperties -object $ct -propertyNames "FieldLinks"
        Invoke-PnPQuery

        $fieldLinksArray = GetFieldLinksAsArray -ContentType $ContentType

        if ($NewPosition -gt $fieldLinksArray.Count)
        {
            Write-Host -ForegroundColor Red "New position $NewPosition is out of range for this content type."
        }
        else
        {
            switch ($Mode)
            {
                "First"
                {
                    $reorderedFieldLinks = MoveToFirstPosition -Array $fieldLinksArray -Element $FieldName

                    $ct.FieldLinks.Reorder($reorderedFieldLinks)
                    $ct.Update($true)
                    Invoke-PnPQuery
                }
                "Last"
                {
                    $reorderedFieldLinks = MoveToLastPosition -Array $fieldLinksArray -Element $FieldName

                    $ct.FieldLinks.Reorder($reorderedFieldLinks)
                    $ct.Update($true)
                    Invoke-PnPQuery
                }
                "Position"
                {
                    if ($PSBoundParameters.ContainsKey("NewPosition") -eq $false)
                    {
                        Write-Host -ForegroundColor Red "Parameter NewPosition is mandatory for Mode 'Position'"
                    }
                    else
                    {
                        $reorderedFieldLinks = MoveElementToPosition -Array $fieldLinksArray -Element $FieldName -Position $NewPosition

                        $ct.FieldLinks.Reorder($reorderedFieldLinks)
                        $ct.Update($true)
                        Invoke-PnPQuery
                    }
                }
            }
        }
    }
}

function GetFieldLinksAsArray
{
    param (
    	[Parameter(Mandatory=$true)]
        [string]$ContentType
    )

    $ct = Get-PnPContentType -Identity $ContentType

    Load-CSOMProperties -object $ct -propertyNames "FieldLinks"
    Invoke-PnPQuery

    $result = @()

    $fieldLinks = $ct.FieldLinks

    foreach ($fieldLink in $fieldLinks)
    {
        $result += $fieldLink.Name
    }

    return $result
}

function MoveElementToPosition
{
    param (
    	[Parameter(Mandatory=$true)]
        [string[]]$Array, 
    	[Parameter(Mandatory=$true)]
        [string]$Element,
    	[Parameter(Mandatory=$true)]
        [int]$Position
    )

    $oldPosition = [Array]::IndexOf($Array, $Element)

    if ($oldPosition -eq -1)
    {
        $result = $Array
    }
    else
    {
        if ($oldPosition -eq $Position)
        {
            $result = $Array
        }
        else
        {
            $result = @()
            $haveSkipped = $false

            for ($i = 0; $i -lt $Array.Count; $i++)
            {
                if ($i -eq $Position) # here we have to insert the element
                {
                    if ($haveSkipped -eq $false)
                    {
                        $result += $Element
                        $result += $Array[$i]
                    }
                    else
                    {
                        $result += $Array[$i]
                        $result += $Element
                    }
                }
                else
                {
                    if ($Array[$i] -eq $Element)
                    {
                        $haveSkipped = $true
                    }
                    else
                    {
                        $result += $Array[$i]
                    }
                }
            }
        }
    }

    return $result
}

function MoveToFirstPosition
{
    param (
    	[Parameter(Mandatory=$true)]
        [string[]]$Array, 
    	[Parameter(Mandatory=$true)]
        [string]$Element
    )

    $reorderedArray = MoveElementToPosition -Array $Array -Element $Element -Position 0

    return $reorderedArray
}

function MoveToLastPosition
{
    param (
    	[Parameter(Mandatory=$true)]
        [string[]]$Array, 
    	[Parameter(Mandatory=$true)]
        [string]$Element
    )

    $oldPosition = [Array]::IndexOf($Array, $Element)

    if ($oldPosition -eq -1)
    {
        $result = $Array
    }
    else
    {
        $result = @()

        for ($i = 0; $i -lt $Array.Count; $i++)
        {
            if ($Array[$i] -eq $Element)
            {
            }
            else
            {
                $result += $Array[$i]
            }
        }

        $result += $Element
    }

    return $result
}

if ($PSBoundParameters.ContainsKey("NewPosition") -eq $false)
{
    SetContentTypeFieldOrder -ContentType $ContentType -FieldName $FieldName -Mode $Mode
}
else
{
    SetContentTypeFieldOrder -ContentType $ContentType -FieldName $FieldName -Mode $Mode -NewPosition $NewPosition
}

Write-Host "Done."