Creating look up column using powershell.

Question

I have a Sharepoint list "Studentparent" in my website. I am trying to create a custom list "studentchild" list using powershell code and this studentchild list will be having a look up column getting ID column from "StudentParent"
list - So the code is 
#To which site u want to create the list 
$spWeb=Get-SPWeb -Identity http://XYZ
#List type or template 
$spTemplate = $spWeb.ListTemplates["Custom List"]
#Get all the lists to the listcollection
$spListCollection=$spWeb.Lists
#adding the new list to the list collection
$spListCollection.Add("StudentChild","StudentChild",$spTemplate)
#get the path of subsite and sitecollecion 
$path = $spWeb.url.trim()
#get the list to the list object
$spList = $spWeb.GetList("$path/Lists/StudentChild")
$ParentList = $spWeb.Lists.item("StudentParent")
$spList = $WebObj.Lists["StudentChild"]
$spList.Fields.AddLookup("ChildLookupField",$ParentList.id,$false)
$spChildListLookupField = $spList.Fields["ChildLookupField"]
$spChildListLookupField.LookupField = $ParentList.Fields["ID"]
$spChildListLookupField.RelationshipDeleteBehavior = [Microsoft.SharePoint.SPRelationshipDeleteBehavior]::Restrict
$spChildListLookupField.Update()
$Views = $spList.Views["All Items"]
$Views.ViewFields.Add("ChildLookupField")
$Views.Update()
but when i run this code - I am getting error
Cannot index into a null array.
+ $spList = $WebObj.Lists["StudentChild"]

Answer 1

Hi Mahesh,
The object "$WebObj" is not instantiated in your code. You have already assigned the value to $splist in following line.
$spList = $spWeb.GetList("$path/Lists/StudentChild")
and once again you are assigning value
$spList = $WebObj.Lists["StudentChild"] // redundant and it should be $spWeb.Lists["StudentChild"]
Please let us know if this fixes your issue.
Thanks,
M. Gubendra Raj