$parent = @"
{
"Property1": "Property1Value",
"Description": "Generic Description",
"SubProperties": {
"SubSubTemplateProps": {
SubSubSubTemplateProps1 : "SubSubSubTemplateProps1",
SubSubSubTemplateProps2 : {
SubSubSubSubTemplateProps1 : [
{
"Key": "Name",
"Value": "Temp"
},
{
"Key": "SupSubSubProp2",
"Value": "Supprop2value"
}
]
}
}
}
}
"@ | ConvertFrom-Json
$templateobj = $parent.SubProperties.SubSubTemplateProps
$parent.SubProperties.psobject.Properties.Remove("SubSubTemplateProps")
for($j = 0; $j -lt 3; $j )
{
$i = "{0:D2}" -f ($j 1)
$letters = @("a","b","c")
foreach($letter in $letters)
{
$newobject = $templateobj
($newobject.SubSubSubTemplateProps2.SubSubSubSubTemplateProps1 | ? {$_.key -eq "Name"}).Value = "NewValue$letter$i"
$parent.SubProperties | Add-Member -MemberType NoteProperty -Name "SubSubProp$letter$i" -Value $newobject
}
}
$parent |convertto-json -Depth 100
Im expecting output like this:
{
"Property1": "Property1Value",
"Description": "Generic Description",
"SubProperties": {
"SubSubPropa01": {
"SubSubSubTemplateProps1": "SubSubSubTemplateProps1",
"SubSubSubTemplateProps2": {
"SubSubSubSubTemplateProps1": [
{
"Key": "Name",
"Value": "NewValuea01"
},
{
"Key": "SupSubSubProp2",
"Value": "Supprop2value"
}
]
}
},
"SubSubPropb01": {
"SubSubSubTemplateProps1": "SubSubSubTemplateProps1",
"SubSubSubTemplateProps2": {
"SubSubSubSubTemplateProps1": [
{
"Key": "Name",
"Value": "NewValueb01"
},
{
"Key": "SupSubSubProp2",
"Value": "Supprop2value"
}
]
}
},
"SubSubPropa02": {
"SubSubSubTemplateProps1": "SubSubSubTemplateProps1",
"SubSubSubTemplateProps2": {
"SubSubSubSubTemplateProps1": [
{
"Key": "Name",
"Value": "NewValuea02"
},
{
"Key": "SupSubSubProp2",
"Value": "Supprop2value"
}
]
}
},
"SubSubPropb02": {
"SubSubSubTemplateProps1": "SubSubSubTemplateProps1",
"SubSubSubTemplateProps2": {
"SubSubSubSubTemplateProps1": [
{
"Key": "Name",
"Value": "NewValueb02"
},
{
"Key": "SupSubSubProp2",
"Value": "Supprop2value"
}
]
}
}
}
}
But I get output like this where all of the noteproperties of the parent are updated instead of just the noteproperty I added. WHAT?!
{
"Property1": "Property1Value",
"Description": "Generic Description",
"SubProperties": {
"SubSubPropa01": {
"SubSubSubTemplateProps1": "SubSubSubTemplateProps1",
"SubSubSubTemplateProps2": {
"SubSubSubSubTemplateProps1": [
{
"Key": "Name",
"Value": "NewValueb02"
},
{
"Key": "SupSubSubProp2",
"Value": "Supprop2value"
}
]
}
},
"SubSubPropb01": {
"SubSubSubTemplateProps1": "SubSubSubTemplateProps1",
"SubSubSubTemplateProps2": {
"SubSubSubSubTemplateProps1": [
{
"Key": "Name",
"Value": "NewValueb02"
},
{
"Key": "SupSubSubProp2",
"Value": "Supprop2value"
}
]
}
},
"SubSubPropa02": {
"SubSubSubTemplateProps1": "SubSubSubTemplateProps1",
"SubSubSubTemplateProps2": {
"SubSubSubSubTemplateProps1": [
{
"Key": "Name",
"Value": "NewValueb02"
},
{
"Key": "SupSubSubProp2",
"Value": "Supprop2value"
}
]
}
},
"SubSubPropb02": {
"SubSubSubTemplateProps1": "SubSubSubTemplateProps1",
"SubSubSubTemplateProps2": {
"SubSubSubSubTemplateProps1": [
{
"Key": "Name",
"Value": "NewValueb02"
},
{
"Key": "SupSubSubProp2",
"Value": "Supprop2value"
}
]
}
}
}
}
Can someone suggest how to copy a node and replace a sub value then add it back to the parent without it overwriting all other child nodes? Not sure why this is happening.
CodePudding user response：
The fundamental problem, as explained in the comments and in more detail in this related answer is:
[pscustomobject]instances, such as returned byConvertFrom-Jsonare instances of a .NET reference type, which means that$newobject = $templateobjdoesn't create a copy of the object stored in$templateobjin$newobject, it creates a copy of the reference to object$templateobj, so that$templateobjand$newobjectend up pointing to the very same object. Only instances of .NET value types are themselves copied with simple assignments - see this answer for background information.
Therefore, you ended up repeatedly modifying the very same object instead of independent copies of it.While
$templateobj.psobject.Copy()is a convenient method to create a shallow clone (copy) of a[pscustomobject]instance, it isn't sufficient in your case, because your instances also contain reference-type instances among the object's property values, which then again get copies as references. In other words: your template object is a[pscustomobject]graph (nested), so it requires deep-cloning, for which there is no built-in method.Note: If you know the structure of the template object ahead of time, there are simpler and more efficient solutions:
Use a literal
[pscustomobject]object definition inside your loop, which creates a new instance every time - see the related answer.Construct your template as an ordered hashtable (
[ordered] @{ ... }), and cast it to[pscustomobject]every time you need a new copy inside the loop - see this answerDefine a custom
classand instantiate it in every loop iteration - see this answer.
If you do need deep-cloning of [pscustomobject] graphs, use helper function Copy-PSCustomObject, defined further below, with the -Deep switch:
$newobject = Copy-PSCustomObject -Deep $templateobj
Helper function Copy-PSCustomObject:
Note: This is not a generic deep-cloning function that works with objects of any type (which would be impossible to implement), but it should work with [pscustomobject] graphs such as returned by ConvertFrom-Json, which limits their composition to:
Primitive JSON types that map onto primitive .NET types and
[string], all of which either are .NET value types or, in the case of[string]act like them.Nested
[pscustomobject]instances with the same composition.Arrays of either.
function Copy-PSCustomObject {
[CmdletBinding()]
param(
[Parameter(Mandatory, ValueFromPipeline)]
[PSCustomObject] $InputObject,
[switch] $Deep
)
begin {
if ($Deep) {
# Helper script block (anonymous function) for walking the object graph
$sb = {
param($original)
$copy = $original.psobject.Copy()
foreach ($prop in $copy.psobject.Properties) {
if ($prop.Value -is [System.Collections.IEnumerable]) { # Presumed array
$prop.Value = @($prop.Value) # Clone array
foreach ($i in 0..($prop.Value.Count-1)) {
$prop.Value[$i] = & $sb $prop.Value[$i] # Recurse
}
}
elseif ($prop.Value -is [System.Management.Automation.PSCustomObject]) {
$prop.Value = & $sb $prop.Value # Recurse
}
# Otherwise: assume it is a value type or string and needs no cloning.
}
# Output the deep-cloned object
$copy
}
}
}
process {
if ($Deep) {
& $sb $InputObject
}
else {
# Shallow copy.
$InputObject.psobject.Copy()
}
}
}