https://contoso.sharepoint.com/sites/Team2/_api/web/lists/getbytitle('SP1')?$select=ID,DefaultDisplayFormUrl,DefaultEditFormUrl,DefaultNewFormUrl

# Set Parameters
$AdminSiteURL="https://contoso-admin.sharepoint.com/"
$SiteURL="https://contoso.sharepoint.com/sites/Team2"
# Connect to SharePoint Online Admin Center
Connect-SPOService -Url $AdminSiteURL 
# Enable Custom Script
Set-SPOSite -Identity $SiteURL -DenyAddAndCustomizePages 0

### Create-DefaultListForms-Interactive.ps1 ###


<#
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 use or distribution of the Sample Code.

 This sample assumes that you are familiar with the programming language being demonstrated and the
 tools used to create and debug procedures. Microsoft support professionals can help explain the
 functionality of a particular procedure, but they will not modify these examples to provide added
 functionality or construct procedures to meet your specific needs. if you have limited programming
 experience, you may want to contact a Microsoft Certified Partner or the Microsoft fee-based consulting
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#>

<#
  .SYNOPSIS
  Script to create default list forms (New, Edit, Display) if they are missing.
  Will also re-add missing Form Webpart to existing list forms if they are missing.

 .DESCRIPTION
  Script to create default list forms (New, Edit, Display) if they are missing.
  Will also re-add missing Form Webpart to existing list forms if they are missing.
  Supply SiteURL and ListName to process a single list, or CSVPath to process multiple lists.
  These input modes cannot be combined. If neither mode is specified, prompts for
  SiteURL and ListName. There is no default CSV path.
  CSV must have siteUrl and listTitle columns with nonblank values in each row.

  Tested with List Templates: 100, 101, 102, 103, 104, 105, 106, 107, 108

  Requires PowerShell 7 compatible with the installed PnP.PowerShell module.
  If PnP.PowerShell is missing, the script will attempt to install it.
  Connections always use interactive authentication with the specified client ID.
  The client ID must identify an Entra ID application configured for PnP interactive
  authentication with appropriate SharePoint delegated permissions and consent.

  .PARAMETER CSVPath
  Specify an explicit path to a CSV file containing siteUrl and listTitle fields.
  Cannot be combined with SiteURL or ListName.

  .PARAMETER SiteURL
  Site URL for a single list. Required with ListName when CSVPath is not supplied.
  Prompts for this value if omitted in single-list mode.

  .PARAMETER ListName
  List name to process at SiteURL. Required with SiteURL when CSVPath is not supplied.
  Prompts for this value if omitted in single-list mode.

  .PARAMETER ClientId
  Required Entra ID application client ID used for interactive authentication.
  You must supply your own client ID; there is no default value.

 .EXAMPLE
  .\Create-DefaultListForms-Interactive.ps1 -ClientId "00000000-0000-0000-0000-000000000001"

  Prompts for SiteURL and ListName, then creates list forms using interactive login.

 .EXAMPLE
  .\Create-DefaultListForms-Interactive.ps1 -CSVPath C:\temp\targetlists.csv -ClientId "00000000-0000-0000-0000-000000000001"

  Creates list forms for rows in the specified CSV using interactive login and your supplied client ID.

 .EXAMPLE
  .\Create-DefaultListForms-Interactive.ps1 -SiteURL "https://contoso.sharepoint.com/sites/team" -ListName "Tasks" -ClientId "00000000-0000-0000-0000-000000000001"

  Creates list forms for the Tasks list at the specified site using interactive login.
#>

[CmdletBinding(DefaultParameterSetName="SingleList")]
param(
    [parameter(Mandatory=$true, ParameterSetName="CSV")]
    [ValidateNotNullOrEmpty()]
    [string]$CSVPath,
    [parameter(Mandatory=$true, ParameterSetName="SingleList")]
    [ValidateNotNullOrEmpty()]
    [ValidatePattern('\S')]
    [string]$SiteURL,
    [parameter(Mandatory=$true, ParameterSetName="SingleList")]
    [ValidateNotNullOrEmpty()]
    [ValidatePattern('\S')]
    [string]$ListName,
    [parameter(Mandatory=$true)]
    [ValidateNotNullOrEmpty()]
    [guid]$ClientId
    )

#############################################

if ($PSCmdlet.ParameterSetName -eq "SingleList") {
    $targets = @([pscustomobject]@{
        siteUrl = $SiteURL
        listTitle = $ListName
    })
}
else {
    $targets = @(Import-Csv -LiteralPath $CSVPath -ErrorAction Stop)
    if ($targets.Count -eq 0) {
        throw "CSV at path '$CSVPath' must contain at least one row with siteUrl and listTitle columns."
    }

    for ($index = 0; $index -lt $targets.Count; $index++) {
        if ([string]::IsNullOrWhiteSpace($targets[$index].siteUrl) -or
            [string]::IsNullOrWhiteSpace($targets[$index].listTitle)) {
            throw "CSV at path '$CSVPath' has missing or blank siteUrl or listTitle values in data row $($index + 1)."
        }
    }
}

#############################################

$module = Get-Module PnP.PowerShell -ListAvailable
if ($null -eq $module) {
    Write-Output "Installing PowerShell Module: PnP.PowerShell"
    Install-Module PnP.PowerShell -Force -AllowClobber -Confirm:$false -ErrorAction Stop
}
Import-Module PnP.PowerShell -ErrorAction Stop

#############################################

$webpartTemplate = @"
<WebPart xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://schemas.microsoft.com/WebPart/v2">
    <Assembly>Microsoft.SharePoint, Version=16.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c</Assembly>
    <TypeName>Microsoft.SharePoint.WebPartPages.ListFormWebPart</TypeName>
    <ListName xmlns="http://schemas.microsoft.com/WebPart/v2/ListForm">{{{LIST_ID}}}</ListName>
    <ListId xmlns="http://schemas.microsoft.com/WebPart/v2/ListForm">{{LIST_ID}}</ListId>
    <PageType xmlns="http://schemas.microsoft.com/WebPart/v2/ListForm">{{PAGE_TYPE}}</PageType>
    <FormType xmlns="http://schemas.microsoft.com/WebPart/v2/ListForm">{{FORM_TYPE}}</FormType>
    <ControlMode xmlns="http://schemas.microsoft.com/WebPart/v2/ListForm">{{CONTROL_MODE}}</ControlMode>
    <ViewFlag xmlns="http://schemas.microsoft.com/WebPart/v2/ListForm">1048576</ViewFlag>
    <ViewFlags xmlns="http://schemas.microsoft.com/WebPart/v2/ListForm">Default</ViewFlags>
    <ListItemId xmlns="http://schemas.microsoft.com/WebPart/v2/ListForm">0</ListItemId>
</WebPart>
"@

Function Create-DefaultListForm
{
    param(
        [parameter(Mandatory=$true)]$List,
        [parameter(Mandatory=$true)][string]$FormUrl,
        [parameter(Mandatory=$true)][ValidateSet("Display", "Edit", "New")]$FormType
    )

    begin { }
    process
    {

        $webpartXml = $webpartTemplate -replace "{{LIST_ID}}", $List.Id.ToString()

        switch ($FormType)
        {
            "Display" {
                $webpartXml = $webpartXml -replace "{{PAGE_TYPE}}", "PAGE_DISPLAYFORM"
                $webpartXml = $webpartXml -replace "{{FORM_TYPE}}", "4"
                $webpartXml = $webpartXml -replace "{{CONTROL_MODE}}", "Display"
                break;
            }
            "Edit" {
                $webpartXml = $webpartXml -replace "{{PAGE_TYPE}}", "PAGE_EDITFORM"
                $webpartXml = $webpartXml -replace "{{FORM_TYPE}}", "6"
                $webpartXml = $webpartXml -replace "{{CONTROL_MODE}}", "Edit"
                break;
            }
            "New" {
                $webpartXml = $webpartXml -replace "{{PAGE_TYPE}}", "PAGE_NEWFORM"
                $webpartXml = $webpartXml -replace "{{FORM_TYPE}}", "8"
                $webpartXml = $webpartXml -replace "{{CONTROL_MODE}}", "New"
                break;
            }
        }

        try
        {
            #Check if form page already exists
            $listPages = Get-PnPProperty -ClientObject $List.RootFolder -Property Files
            $formPage = $listPages | Where-Object { $_.ServerRelativeUrl.ToLower() -eq $FormUrl.ToLower() }

            if ($null -eq $formPage) {
                Write-Output "  [Creating Form Page] $FormUrl"

                #Create Form
                $formPage = $List.RootFolder.Files.AddTemplateFile($FormUrl, [Microsoft.SharePoint.Client.TemplateFileType]::FormPage)
            }
            else {
                #Form page exists, check if form is recognized by list (i.e. form page has a form webpart on it)
                $listForms = Get-PnPProperty -ClientObject $List -Property Forms

                if ($null -ne $listForms -and $listForms.Count -gt 0) {
                    $existingForm = $list.Forms | Where-Object { $_.ServerRelativeUrl.ToLower() -eq $FormUrl.ToLower() }
                    if ($null -ne $existingForm) {
                        Write-Warning "  [Form Already Exists] $FormUrl"
                        return;
                    }
                }
            }

            Write-Output "  [Adding Form Webpart] $FormUrl"
            #Get Webpart Manager for Form
            $wpm = $formPage.GetLimitedWebPartManager([Microsoft.SharePoint.Client.WebParts.PersonalizationScope]::Shared)

            #Import Webpart on page
            $wp = $wpm.ImportWebPart($webpartXml)

            #Add webpart to Form
            $wpm.AddWebPart($wp.WebPart, "Main", 1) | Out-Null

            #Execute changes
            $List.Context.ExecuteQuery()
        }
        catch
        {
            Write-Error "Error creating form $FormType at $FormUrl. Error: $($_.Exception)"
        }
    }
    end { }
}

#############################################

foreach ($row in $targets)
{
    Write-Output "[$($row.siteUrl)] [$($row.listTitle)]"

    Connect-PnPOnline -Url $row.siteUrl -Interactive -ClientId $ClientId.ToString() -ErrorAction Stop
    $list = Get-PnPList $row.listTitle
    $listUrl = $list.RootFolder.ServerRelativeUrl

    # Handle Document Library Types
    if ($list.BaseType -eq [Microsoft.SharePoint.Client.BaseType]::DocumentLibrary) {
        Write-Host " > Processing Library: $listUrl"
        Create-DefaultListForm -List $list -FormUrl "$listUrl/Forms/Upload.aspx"   -FormType New
        Create-DefaultListForm -List $list -FormUrl "$listUrl/Forms/DispForm.aspx" -FormType Display
        Create-DefaultListForm -List $list -FormUrl "$listUrl/Forms/EditForm.aspx" -FormType Edit
    }

    # Handle Generic List Types
    else {
        Write-Host " > Processing List: $listUrl"
        Create-DefaultListForm -List $list -FormUrl "$listUrl/NewForm.aspx"  -FormType New
        Create-DefaultListForm -List $list -FormUrl "$listUrl/DispForm.aspx" -FormType Display
        Create-DefaultListForm -List $list -FormUrl "$listUrl/EditForm.aspx" -FormType Edit
    }
}