Adding choice to field associated to Content Type

Question

I have the following script :

$site = new-object Microsoft.SharePoint.SPSite("http://TEST123")
$web = $site.OpenWeb()
$ct=$web.ContentTypes["MyCT"]  
$field = $ct.Fields.GetFieldByInternalName("AddTESTColumn")                            
$ct.FieldLinks[$field.id].DisplayName ="AddTESTColumn"     
$ct.Update();

I have used the above to update the display name of a column that is associated to CT.

But now I want to update a choice field column so will be adding a new choice "away" to the current choices tried to use the choices.add but keep getting error message

I used the following :

$site = Get-SPSite -Identity "http://TEST123"

$web = $site.RootWeb
$field = 
$web.Fields["AddTESTColumn"];
$field.choices.add("away")
$field.update();

and get the following message:

You cannot call a method on a null-valued expression.

the issue is with $field = $web.Fields["AddTESTColumn"]; as its not recognising the field name even though it exist. I have used both internal and display name, same issue.

Answer 1

If it is a Site Column then your code is fine.

$site = Get-SPSite -Identity "http://TEST123"    
$web = $site.RootWeb
$field = $web.Fields["SiteColumnInternalName"];
$field.choices.add("away") 
$field.update();

If it is a list column and not a site column, then try the code below.

$site = Get-SPSite -Identity "http://TEST123"    
$web = $site.RootWeb
$List = $web.Lists["ListName"]
$field = $list.Fields.GetField("ColumnInternalName");
$field.Choices.Add("away") 
$field.update();