In PowerShell (v2), how do you add private members to a PSObject?
That is, members that can only be accessed via $this from within a ScriptProperty or ScriptMethod.
Prior to the introduction of classes in version 5.0, the PowerShell extended type system (ETS) doesn't have the same concept of access modifiers as the underlying type system (.NET/CTS) has.
One way of hinting at "don't use this directly" to users, would be to have a prefix for "internal" properties, like __ (double underscore):
$object = New-Object psobject -Property #{
Public = 4
__private = 9
} |Add-Member -MemberType ScriptProperty -Name Private -Value {
$this.__private
} -SecondValue {
param([int]$newValue)
if(($newValue % 3) -ne 0){
Write-Warning "Only multiples of 3 allowed"
} else {
$this.__private = $newValue
}
} -PassThru
Related
my goal is: Get the items within the folders in a SharePoint 2010 library. I'm struggling trying to get some Items from a SharePoint 2010 Library using CSOM with PowerShell.
I tried three different methods that i found in the internet but still without success. Also the Microsoft's Documentation is really sh*t in this aspect, hope somebody can help me. So here we go:
1.Method A
[Microsoft.SharePoint.Client.FileInformation]$fileInfo = [Microsoft.SharePoint.Client.File]::OpenBinaryDirect($ctx, $file.ServerRelativeUrl);
[System.IO.FileStream]$writeStream = [System.IO.File]::Open("$($libraryTargetPath)\$($file.Name)", [System.IO.FileMode]::Create);
$fileInfo.Stream.CopyTo($writeStream);
$writeStream.Close();
With the A method I get this error:
Method invocation failed because [System.Net.ConnectStream] doesn't contain a method named 'CopyTo'.
+ $fileInfo.Stream.CopyTo <<<< ($writeStream);
+ CategoryInfo : InvalidOperation: (CopyTo:String) [], RuntimeException
+ FullyQualifiedErrorId : MethodNotFound
The [System.Net.ConnectStream] can't find the method CopyTo
I was lookign information about this, in the System.Net namespace and in the "Microsoft.SharePoint.Client.FileInformation" class but without success :(
2.Method B
$binary = [Microsoft.SharePoint.Client.File]::OpenBinaryDirect($ctx, $file.ServerRelativeUrl)
$Action = [System.IO.FileMode]::Create
$new = "$($libraryTargetPath)\$($file.Name)"
$stream = New-Object System.IO.FileStream $new, $Action
$writer = New-Object System.IO.BinaryWriter($stream)
$writer.write($binary)
$writer.Close()
Method B don't give me a error, but in stead of downloading the Items, it makes empty files in the destination folder. So this method isn't downloading the items, just making new files.
3.Method C
$binary = $file.OpenBinary()
$stream = New-Object System.IO.FileStream("$($libraryTargetPath)\$($file.Name)"), Create
$writer = New-Object System.IO.BinaryWriter($stream)
$writer.write($binary)
$writer.Close()
I'm not sure if method C belongs to CSOM or to the SharPoint built-in Server side client, if it's so please let me know. This is the error i'm getting:
Method invocation failed because [Microsoft.SharePoint.Client.File] doesn't contain a method named 'OpenBinary'.
At C:\Users\Administrator\Desktop\SharePointOnPremisesBackUp\SharePointOnPremisesBackUp.ps1:77 char:31
+ $binary = $file.OpenBinary <<<< ()
+ CategoryInfo : InvalidOperation: (OpenBinary:String) [], RuntimeException
+ FullyQualifiedErrorId : MethodNotFound
And here PowerShell can't find the OpenBinary() method in Microsoft.SharePoint.Client.File and there is nearly not information about this method.
Here is the complete function I'm trying to use:
function GetDocumentLibs ($ctx, $web)
{
Function IterateFoldersRecursively([Microsoft.SharePoint.Client.Folder]$folder, [Microsoft.SharePoint.Client.ClientContext]$ctx)
{
# make sure that the "Web.Context.Url" is the current web url
if ($web.Context.Url.StartsWith($SiteCollectionUrl) -eq $true)
{
$files = $folder.Files
$ctx.Load($folder.Files)
$ctx.Load($folder.Folders)
$ctx.ExecuteQuery()
foreach ($subFolder in $folder.Folders)
{
IterateFoldersRecursively $subFolder $ctx
}
# Check if folder Exist and Skip
$libraryTargetPath = "$($TargetPath)\$($folder.ServerRelativeUrl.Replace('/', '\'))"
New-Item -Path $libraryTargetPath -ItemType Directory -Force
foreach ($file in $files)
{
# Method 1
[Microsoft.SharePoint.Client.FileInformation]$fileInfo = [Microsoft.SharePoint.Client.File]::OpenBinaryDirect($ctx, $file.ServerRelativeUrl);
[System.IO.FileStream]$writeStream = [System.IO.File]::Open("$($libraryTargetPath)\$($file.Name)", [System.IO.FileMode]::Create);
$fileInfo.Stream.CopyTo($writeStream)
$writeStream.Close()
# Method 2
$binary = [Microsoft.SharePoint.Client.File]::OpenBinaryDirect($ctx, $file.ServerRelativeUrl)
$Action = [System.IO.FileMode]::Create
$new = "$($libraryTargetPath)\$($file.Name)"
$stream = New-Object System.IO.FileStream $new, $Action
$writer = New-Object System.IO.BinaryWriter($stream)
$writer.write($binary)
$writer.Close()
# Method 3
$binary = $file.OpenBinary()
$stream = New-Object System.IO.FileStream("$($libraryTargetPath)\$($file.Name)"), Create
$writer = New-Object System.IO.BinaryWriter($stream)
$writer.write($binary)
$writer.Close()
# delete folder
}
}
}
$folder = $web.GetFolderByServerRelativeUrl($web.ServerRelativeUrl)
$ctx.Load($folder)
$ctx.ExecuteQuery()
IterateFoldersRecursively $folder $ctx
}
the tools I'm using:
Sapien's PowerShell Studio
PowerShell V2 with CSOM
SharePoint 2010 OnPremises
Please if you have any Solution, Reference, Documentation or tutorial that can be useful tell me. Thanks in advance.
After a lot of research i found a solution and decide to use this method:
function GetDocumentLibs ($ctx, $web)
{
$site = $ctx.Site
$ctx.Load($site)
$ctx.ExecuteQuery()
$siteUrl = $site.Url
Function IterateFoldersRecursively([Microsoft.SharePoint.Client.Folder]$folder, [Microsoft.SharePoint.Client.ClientContext]$ctx)
{
if ($web.Context.Url.StartsWith($SiteCollectionUrl) -eq $true)
{
$files = $folder.Files
$ctx.Load($folder.Files)
$ctx.Load($folder.Folders)
$ctx.ExecuteQuery()
foreach ($subFolder in $folder.Folders)
{
IterateFoldersRecursively $subFolder $ctx
}
$targetPath = "$($TargetPath)\$($folder.ServerRelativeUrl.Replace('/', '\'))"
New-Item -Path $targetPath -ItemType Directory -Force
foreach ($file in $files)
{
$client = new-object System.Net.WebClient
$client.UseDefaultCredentials = $true
$client.DownloadFile("$($siteUrl)$($file.ServerRelativeUrl)", "$($targetPath)\$($file.Name)")
}
}
}
$folder = $web.GetFolderByServerRelativeUrl($web.ServerRelativeUrl)
$ctx.Load($folder)
$ctx.ExecuteQuery()
IterateFoldersRecursively $folder $ctx
}
Remember to implement some exception handling.
I hope this is helpful for somebody with the same problem.
I'm already in love with the Custom Fields feature in Trello. Is there a way to get and set custom fields via the API?
I tried using the get field API call to get a field (on a board with a custom field defined called "MyCustomField"):
curl "https://api.trello.com/1/cards/57c473503a5ef0b76fddd0e5/MyCustomField?key=${TRELLO_API_KEY}&token=${TRELLO_OAUTH_TOKEN}"
to no avail.
The Custom Fields API from Trello is now officially available (announcement blog post here).
It allows users to manipulate both custom field items of boards and custom field item values on cards.
Custom Fields API documentation
Getting customFieldItems For Cards
Setting & Updating CustomFieldItems
This is just to add to bdwakefield's answer. His solution involves hard coding the names of the field ids.
If you want to also retrieve the name of the fields themselves (for example get that "ZIn76ljn-4yeYvz" is actually "priority" in Trello, without needing to hard code it, call the following end point:
boards/{trello board id}/pluginData
This will return an array with the plugins information and in one of the array items, it will include a line along the lines of:
[value] => {"fields":[{"n":"~custom field name~:","t":0,"b":1,"id":"~custom field id that is the weird stuff at the card level~","friendlyType":"Text"}]}
So you just need to figure out the plugin for custom fields in your case, and you can retrieve the key -> value pair for the custom field name and the id associated with it.
It means that if you add / remove fields, or rename them, you can handle it at run time vs changing your code.
This will also give you the options for the custom field (when it is a dropdown like in bdwakefield's example above).
So I have a "sort of" answer to this. It requires some hackery on your part to make it work and there is more than a little manual upkeep as you add properties or values -- but it works.
I am doing this in powershell (I am NOT well versed in ps just yet and this my first really 'big' script that I have pulled together for it) since my intent is to use this with TFS Builds to automate moving some cards around and creating release notes. We are using custom fields to help us classify the card and note estimate/actual hours etc. I used this guys work as a basis for my own scripting. I am not including everything but you should be able to piece everything together.
I have left out everything with connecting to Trello and all that. I have a bunch of other functions for gettings lists, moving cards, adding comments etc. The ps module I linked above has a lot of that built in as well.
function Get-TrelloCardPluginData
{
[CmdletBinding()]
param
(
[Parameter(Mandatory,ValueFromPipelineByPropertyName)]
[ValidateNotNullOrEmpty()]
[Alias('Id')]
[string]$CardId
)
begin
{
$ErrorActionPreference = 'Stop'
}
process
{
try
{
$uri = "$baseUrl/cards/$CardId/pluginData?$($trelloConfig.String)"
$result = Invoke-RestMethod -Uri $uri -Method GET
return $result
}
catch
{
Write-Error $_.Exception.Message
}
}
}
You'll get data that looks like this:
#{id=582b5ec8df1572e572411513; idPlugin=56d5e249a98895a9797bebb9;
scope=card; idModel=58263201749710ed3c706bef;
value={"fields":{"ZIn76ljn-4yeYvz":2,"ZIn76ljn-c2yhZH":1}};
access=shared}
#{id=5834536fcff0525f26f9e53b; idPlugin=56d5e249a98895a9797bebb9;
scope=card; idModel=567031ea6a01f722978b795d;
value={"fields":{"ZIn76ljn-4yeYvz":4,"ZIn76ljn-c2yhZH":3}};
access=shared}
The fields collection is basically key/pair. The random characters correspond to the property and the value after that is what was set on the custom property. In this case it is an 'index' for the value in the dropdown. These two fields have a 'priority' (low, medium, high) and a 'classification' (Bug, Change Request, etc) for us. (We are using labels for something else).
So you'll have to create another fucntion where you can parse this data out. I am sure there are better ways to do it -- but this is what I have now:
function Get-TrelloCustomPropertyData($propertyData)
{
$data = $propertyData.Replace('{"fields":{', '')
$data = $data.Replace('}}', '')
$data = $data.Replace('"', '')
$sepone = ","
$septwo = ":"
$options = [System.StringSplitOptions]::RemoveEmptyEntries
$obj = $data.Split($sepone, $options)
$cardCustomFields = Get-TrelloCustomFieldObject
foreach($pair in $obj)
{
$field = $pair.Split($septwo,$options)
if (-Not [string]::IsNullOrWhiteSpace($field[0].Trim()))
{
switch($field[0].Trim())
{
'ZIn76ljn-4yeYvz' {
switch($field[1].Trim())
{
'1'{
$cardCustomFields.Priority = "Critical"
}
'2'{
$cardCustomFields.Priority = "High"
}
'3'{
$cardCustomFields.Priority = "Medium"
}
'4'{
$cardCustomFields.Priority = "Low"
}
}
}
'ZIn76ljn-c2yhZH' {
switch($field[1].Trim())
{
'1'{
$cardCustomFields.Classification = "Bug"
}
'2'{
$cardCustomFields.Classification = "Change Request"
}
'3'{
$cardCustomFields.Classification = "New Development"
}
}
}
'ZIn76ljn-uJyxzA'{$cardCustomFields.Estimated = $field[1].Trim()}
'ZIn76ljn-AwYurD'{$cardCustomFields.Actual = $field[1].Trim()}
}
}
}
return $cardCustomFields
}
Get-TrelloCustomFieldObject is another ps function that I set up to build an object based on the properties I know that I have defined.
function Get-TrelloCustomFieldObject
{
[CmdletBinding()]
param()
begin
{
$ErrorActionPreference = 'Stop'
}
process
{
$ccf = New-Object System.Object
$ccf | Add-Member -type NoteProperty -name Priority -value "None"
$ccf | Add-Member -type NoteProperty -name Classification -value "None"
$ccf | Add-Member -type NoteProperty -name Estimated -value ""
$ccf | Add-Member -type NoteProperty -name Actual -value ""
return $ccf
}
}
I'm struggling since a couple of days to upload files to Sharepoint 2010 with powershell.
I'm on a win7 machine with powershell v2 trying to upload to a SP 2010 site.
I'm having 2 major issues
$Context.web value is always empty even after Executequery() and no
error is shown. My $Context variable gets the server version (14.x.x.x.x) but nothing more
$Context.Load($variable) which always returns the error Cannot find an overload for "Load" and the argument count: "1".
I copied Sharepoint DLLs to my Win7 machine and I import the reference to my script.
The below script is a mix of many parts I took from the net.
I'v already tried unsuccessfully to add an overload on the clientcontext defining Load method without Type parameter suggested in the following post
http://soerennielsen.wordpress.com/2013/08/25/use-csom-from-powershell/
[System.Reflection.Assembly]::LoadWithPartialName("Microsoft.SharePoint.Client")
[System.Reflection.Assembly]::LoadWithPartialName("Microsoft.SharePoint.Client.Runtime")
$site = "https://Root-of-my-site"
$listname = "My-folder"
$context = New-Object Microsoft.SharePoint.Client.ClientContext($site)
[Microsoft.SharePoint.Client.Web]$web = $context.Web
[Microsoft.SharePoint.Client.List]$list = $web.Lists.GetByTitle($listName)
$Folder = "C:\temp\Certificates"
$List = $Context.Web.Lists.GetByTitle($listname)
Foreach ($File in (dir $Folder))
{
$FileCreationInfo = New-Object Microsoft.SharePoint.Client.FileCreationInformation
$FileCreationInfo.Overwrite = $true
$FileCreationInfo.Content = get-content -encoding byte -path $File.Fullname
$FileCreationInfo.URL = $File
$Upload = $List.RootFolder.Files.Add($FileCreationInfo)
$Context.Load($Upload)
$Context.ExecuteQuery()
}
The error is
Cannot find an overload for "Load" and the argument count: "1".
At C:\temp\uploadCertToSharepoint.ps1:48 char:14
+ $Context.Load <<<< ($Upload)
+ CategoryInfo : NotSpecified: (:) [], MethodException
+ FullyQualifiedErrorId : MethodCountCouldNotFindBest
Can someone please help me sorting this issue?
I'll need to upload around 400 files with ad-hoc fields to a sharepoint site in a couple of weeks and at the moment I'm completely stuck. Running the script server side is unfortunately not possible.
Thanks,
Marco
This error occurs since ClientRuntimeContext.Load is a Generics Method:
public void Load<T>(
T clientObject,
params Expression<Func<T, Object>>[] retrievals
)
where T : ClientObject
and Generics methods are not supported natively in PowerShell (V1, V2) AFAIK.
The workaround is to invoke a generic methods using MethodInfo.MakeGenericMethod method as described in article Invoking Generic Methods on Non-Generic Classes in PowerShell
In case of ClientRuntimeContext.Load method, the following PS function could be used:
Function Invoke-LoadMethod() {
param(
$clientObjectInstance = $(throw “Please provide an Client Object instance on which to invoke the generic method”)
)
$ctx = $clientObjectInstance.Context
$load = [Microsoft.SharePoint.Client.ClientContext].GetMethod("Load")
$type = $clientObjectInstance.GetType()
$clientObjectLoad = $load.MakeGenericMethod($type)
$clientObjectLoad.Invoke($ctx,#($clientObjectInstance,$null))
}
Then, in your example the line:
$Context.Load($Upload)
could be replaced with this one:
Invoke-LoadMethod -clientObjectInstance $Upload
References
Invoking Generic Methods on Non-Generic Classes in PowerShell
Some tips and tricks of using SharePoint Client Object Model in
PowerShell. Part 1
It throws the error because in powershell 2.0 you cannot call generic method directly.
You need to create closed method using MakeGenericMethod. Try to use code below.
[System.Reflection.Assembly]::LoadWithPartialName("Microsoft.SharePoint.Client")
[System.Reflection.Assembly]::LoadWithPartialName("Microsoft.SharePoint.Client.Runtime")
$site = "http://server"
$listname = "listName"
$Folder = "C:\PS\Test"
$context = New-Object Microsoft.SharePoint.Client.ClientContext($site)
[Microsoft.SharePoint.Client.Web]$web = $context.Web
[Microsoft.SharePoint.Client.List]$list = $web.Lists.GetByTitle($listName)
$method = $Context.GetType().GetMethod("Load")
$closedMethod = $method.MakeGenericMethod([Microsoft.SharePoint.Client.File])
Foreach ($File in (dir $Folder))
{
$FileCreationInfo = New-Object Microsoft.SharePoint.Client.FileCreationInformation
$FileCreationInfo.Overwrite = $true
$FileCreationInfo.Content = (get-content -encoding byte -path $File.Fullname)
$FileCreationInfo.URL = $File
$Upload = $List.RootFolder.Files.Add($FileCreationInfo)
$closedMethod.Invoke($Context, #($Upload, $null) )
$Context.ExecuteQuery()
}
I'm attempting to make a Powershell module to work with an external API. I have a custom object which looks like this:
$Subscriber = New-Module -AsCustomObject -ScriptBlock {
[string] $EmailAddress=$null
[string] $Name=$null
[bool] $Resubscribe=$false
[bool] $RestartSubscriptionBasedAutoresponders=$false
Export-ModuleMember -Variable * -Function *
}
Now, I'd like this object to be able to implement a function which outputs itself in JSON format. I'm aware that the normal way to do this is: $Subscriber | ConvertTo-Json but instead, I'd like this object to implement something along these lines:
$Subscriber = New-Module -AsCustomObject -ScriptBlock {
[string] $EmailAddress=$null
[string] $Name=$null
[bool] $Resubscribe=$false
[bool] $RestartSubscriptionBasedAutoresponders=$false
Function ToJson {
$this | ConvertTo-Json
}
Export-ModuleMember -Variable * -Function *
}
But my problem is that there is no $this variable nor have I been able to find any information about any other way to do it. Am I simply attempting to misuse Powershell to such a degree that this isn't supported at all? Or am I just missing something obvious? I'm open to any critique and advice :)
I didn't test it extensively, give it a try. It evaluates the $^ automatic variable which contains the first token in the last line received by the session (the variable name).
function ToJson { Invoke-Expression "$^" | ConvertTo-Json }
The variables you define at module scope (eg. $EmailAddress) can be accessed1 from inside functions defined in the module.
However ConvertTo-Json converts a single object from the pipeline.
Therefore you would be better defining a single object, and passing that through:
$Subscriber = New-Module -AsCustomObject -ScriptBlock {
$data = New-Object PSObject -Property #{
EmailAddress=$null;
Name=$null;
Resubscribe=$false;
RestartSubscriptionBasedAutoresponders=$false
}
Function ToJson {
$data | ConvertTo-Json
}
Export-ModuleMember -Variable * -Function *
}
But this wouldn't really fix with the -AsCustomObject, so that conversion to a single object could be done inside ToJson:
$Subscriber = New-Module -AsCustomObject -ScriptBlock {
[string] $EmailAddress=$null
[string] $Name=$null
[bool] $Resubscribe=$false
[bool] $RestartSubscriptionBasedAutoresponders=$false
Function ToJson {
New-Object PSObject -Property #{
EmailAddress=$EmailAddress;
Name=$Name;
Resubscribe=$Resubscribe;
RestartSubscriptionBasedAutoresponders=$RestartSubscriptionBasedAutoresponders
} | ConvertTo-Json
}
Export-ModuleMember -Variable * -Function *
}
(And, as far as I am aware, there is no single $this in this case: there certainly isn't for .psm1 type modules.)
1 And updated if you use the script: scope prefix.
Hi i am not exactly sure if my wording is right but i need a variable which contains current date/time whenever i write data to log ; how can i do that without initializing everytime.Currently everytime i need a update i use these both statements jointly.Is there an other way of doing this?
$DateTime = get-date | select datetime
Add-Content $LogFile -Value "$DateTime.DateTime: XXXXX"
please do let me know if any questions or clarifications regarding my question.
This script make the real Dynamic variable in Powershell ( Thanks to Lee Holmes and his Windows PowerShell Cookbook The Complete Guide to Scripting Microsoft's Command Shell, 3rd Edition)
##############################################################################
##
## New-DynamicVariable
##
## From Windows PowerShell Cookbook (O'Reilly)
## by Lee Holmes (http://www.leeholmes.com/guide)
##
##############################################################################
<#
.SYNOPSIS
Creates a variable that supports scripted actions for its getter and setter
.EXAMPLE
PS > .\New-DynamicVariable GLOBAL:WindowTitle `
-Getter { $host.UI.RawUI.WindowTitle } `
-Setter { $host.UI.RawUI.WindowTitle = $args[0] }
PS > $windowTitle
Administrator: C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe
PS > $windowTitle = "Test"
PS > $windowTitle
Test
#>
param(
## The name for the dynamic variable
[Parameter(Mandatory = $true)]
$Name,
## The scriptblock to invoke when getting the value of the variable
[Parameter(Mandatory = $true)]
[ScriptBlock] $Getter,
## The scriptblock to invoke when setting the value of the variable
[ScriptBlock] $Setter
)
Set-StrictMode -Version 3
Add-Type #"
using System;
using System.Collections.ObjectModel;
using System.Management.Automation;
namespace Lee.Holmes
{
public class DynamicVariable : PSVariable
{
public DynamicVariable(
string name,
ScriptBlock scriptGetter,
ScriptBlock scriptSetter)
: base(name, null, ScopedItemOptions.AllScope)
{
getter = scriptGetter;
setter = scriptSetter;
}
private ScriptBlock getter;
private ScriptBlock setter;
public override object Value
{
get
{
if(getter != null)
{
Collection<PSObject> results = getter.Invoke();
if(results.Count == 1)
{
return results[0];
}
else
{
PSObject[] returnResults =
new PSObject[results.Count];
results.CopyTo(returnResults, 0);
return returnResults;
}
}
else { return null; }
}
set
{
if(setter != null) { setter.Invoke(value); }
}
}
}
}
"#
## If we've already defined the variable, remove it.
if(Test-Path variable:\$name)
{
Remove-Item variable:\$name -Force
}
## Set the new variable, along with its getter and setter.
$executioncontext.SessionState.PSVariable.Set(
(New-Object Lee.Holmes.DynamicVariable $name,$getter,$setter))
There's a Set-StrictMode -Version 3 but you can set it as -Version 2 if you can load framework 4.0 in your powershell V2.0 session as explained Here
The use for the OP is:
New-DynamicVariable -Name GLOBAL:now -Getter { (get-date).datetime }
Here the Lee Holmes's evaluation (where it is clear what is the real flaw) about the method I used in my other answer:
Note
There are innovative solutions on the Internet that use PowerShell's debugging facilities to create a breakpoint that changes a variable's value whenever you attempt to read from it. While unique, this solution causes PowerShell to think that any scripts that rely on the variable are in debugging mode. This, unfortunately, prevents PowerShell from enabling some important performance optimizations in those scripts.
Why not use:
Add-Content $LogFile -Value "$((Get-Date).DateTime): XXXXX"
This gets the current datetime every time. Notice that it's inside $( ) which makes powershell run the expression(get the datetime) before inserting it into the string.
wrap your two commands in function so you will have just one call ?
function add-log{
(param $txt)
$DateTime = get-date | select -expand datetime
Add-Content $LogFile -Value "$DateTime: $txt"
}
Besides these other ways (which frankly I would probably use instead - except the breakpoint approach), you can create a custom object with a ScriptProperty that you can provide the implementation for:
$obj = new-object pscustomobject
$obj | Add-Member ScriptProperty Now -Value { Get-Date }
$obj.now
Using PsBreakPoint:
$act= #'
$global:now = (get-date).datetime
'#
$global:sb = [scriptblock]::Create($act)
$now = Set-PSBreakpoint -Variable now -Mode Read -Action $global:sb
calling $now returns current updated datetime value
One liner:
$now = Set-PSBreakpoint -Variable now -Mode Read -Action { $global:now = (get-date).datetime }