Powershell to add/delete content type to particular library alone in a site collection

Question

Hi,
I am trying to add and delete content type from a particular picture library (site collection) using powershell.
I have tried the below, but it is not working.
Below scenarios are not working:
1) If the content type to be added is there in library, then the loop is still moving to "No content type exists".
2) Content type is not getting deleted from library
3) Set the newly added content type as default content type.
Below is the powershell, which I am trying:
function ChangeContentType($url)
$site = Get-SPSite($url);
$web =$site.RootWeb
$lookForList = "PicLibrary"
$lookForCT = "Img1ContentType"
$lookForRemoveCT = "Image2CT"
write-host "Checking site:"$web.Title
#Make sure content types are allowed on the list specified
$docLibrary = $web.Lists[$lookForList]
if ($docLibrary -ne $null)
$docLibrary.ContentTypesEnabled = $true
$docLibrary.Update()
if (($web.ContentTypes | where { $web.Name -eq $lookForCT }) -eq $null)
write-host "No content type exists with the name" $lookForCT "on list" $docLibrary.Title
#Add site content types to the list
write-host "Adding content type " $lookForCT "on list" $docLibrary.Title
$ctToAdd = $web.ContentTypes[$lookForCT]
$ct = $docLibrary.ContentTypes.Add($ctToAdd)
write-host "Content type" $ct.Name "added to list" $docLibrary.Title
$docLibrary.Update();
else
write-host "content type exists with the name" $lookForCT "on list" $docLibrary.Title
#Remove Content type
if (($web.ContentTypes | where { $web.Name -eq $lookForRemoveCT }) -eq $null)
write-host "No content type exists with the name" $lookForRemoveCT "on list" $docLibrary.Title
else
$ctToRemove = $web.ContentTypes[$lookForRemoveCT]
write-host "Removing content type" $ctToRemove.Name "from list" $docLibrary.Title
$docLibrary.ContentTypes.Delete($ctToRemove.Id)
$docLibrary.Update()
else
write-host "The list" $lookForList "does not exist in site" $web.Title
#Dispose object
$site.Dispose()
$web.Dispose()
How to fix this?
Thanks

Answer 1

Hi,
Thanks for the reply.
I checked it. If the script is run multiple times, the add and delete content type will throw error.
How to delete content type? I have tried the below:
$docLibrary = $web.Lists[$lookForList]
if ($docLibrary -ne $null)
$docLibrary.ContentTypesEnabled = $true
$docLibrary.Update()
#get the content Type
Write-host "Getting content type $lookForCT in site $web"
#Confirm that the content type exists.
$contentType = $web.ContentTypes | where {$web.ContentTypes.Name -eq $lookForCT}
##Abort if not found.
if ($contentType -eq $null)
Write-host "$lookForCT not found in site collection."
else
if ($web.ContentTypes.Name -eq $lookForCT)
Write-host $docLibrary.ContentTypes.Name
if($docLibrary.ContentTypes.Name -eq $lookForCT)
write-host "Content type $lookForCT is already added to list" $docLibrary.Title
else
write-host "No content type exists with the name" $lookForCT "on list" $docLibrary.Title
write-host "Adding Content Type"
$ctToAdd = $web.ContentTypes[$lookForCT]
$ct = $docLibrary.ContentTypes.Add($ctToAdd)
$docLibrary.Update()
write-host "Content type" $ct.Name "added to list" $docLibrary.Title
#get the content Type
Write-host "Getting content type $lookForRemoveCT in site $web"
#Confirm that the content type exists.
$contentType = $web.ContentTypes | where {$web.ContentTypes.Name -eq $lookForRemoveCT}
##Abort if not found.
if ($contentType -eq $null)
Write-host "$lookForRemoveCT not found in site collection."
else
if ($web.ContentTypes.Name -eq $lookForRemoveCT)
Write-host $docLibrary.ContentTypes.Name
if($docLibrary.ContentTypes.Name -eq $lookForRemoveCT)
write-host "Content type $lookForRemoveCT is added to list" $docLibrary.Title.
write-host "Removing Content type $lookForRemoveCT"
$ctToRemove = $web.ContentTypes[$lookForRemoveCT]
$docLibrary.ContentTypes.Delete($ctToRemove.Id)
$docLibrary.Update()
else
write-host "No content type exists with the name" $lookForRemoveCT "on list" $docLibrary.Title
I am getting error in delete now. Error is "Exception calling "Delete" with "1" argument(s): "Specified argument was out of the range of valid values.
Parameter name: id"
Thanks