Help New-item -parameter "Value"

show us -Value <System.Object> could be bind ByPropertyName or ByValue. The question is:

** Is it possible pipe ByPropertyName? **

As ByValue takes precedence over ByPropertyName, I can't find any example to be able to do that pipe. Anything I write to the left is an object, and is bound by ByValue, even if that object has the -Value attribute.

Thank you

Example:

$customObject = [PSCustomObject]@{
    Value = "Lorem ipsum"
}

$customObject | New-Item -Name BPN_value.txt

The content of BPN_value.txt is @{Value = "Lorem ipsum"} because $customObject is an object (obviously) and it's binding byValue to the paramete Value of New_Item

CodePudding user response：

Is it possible to bind New-Item -Value parameter ByPropertyName?

No, because as you have already noticed, the parameter type is System.Object and since all objects inherit from this class every input from pipeline is bound with ValueFromPipeline instead of ValueFromPipelineByPropertyName.

Should the type for this parameter be other than System.Object?

No, because it would conflict with other providers. In example, defining a new function would no longer be possible:

$null = New-Item -Path function:Say-Hello -Value {
    'hey there'
}

Say-Hello

Should the -Value parameter be enabled to bind by Property Name?

Probably not, because it can never be bound by it.

Is there a workaround?

You could have a ProxyCommand or wrapper function around New-Item that changes the parameter type from System.Object to System.String, this way the function would be able to work properly taking ValueFromPipeline and ValueFromPipelineByPropertyName. You could then store this wrapper in your $PROFILE and have it available for you each time a new session is started.

For the reasons stated before, this wrapper would only work targetting the FileSystem provider and has been hardcoded for ItemType = File.

function New-File {
    [CmdletBinding(DefaultParameterSetName='pathSet', SupportsShouldProcess=$true, ConfirmImpact='Medium', HelpUri='https://go.microsoft.com/fwlink/?LinkID=2096592')]
    param(
        [Parameter(ParameterSetName='pathSet', Mandatory=$true, Position=0, ValueFromPipelineByPropertyName=$true)]
        [Parameter(ParameterSetName='nameSet', Position=0, ValueFromPipelineByPropertyName=$true)]
        [string[]]
        ${Path},

        [Parameter(ParameterSetName='nameSet', Mandatory=$true, ValueFromPipelineByPropertyName=$true)]
        [AllowNull()]
        [AllowEmptyString()]
        [string]
        ${Name},

        [Parameter(ValueFromPipeline=$true, ValueFromPipelineByPropertyName=$true)]
        [Alias('Target')]
        [string]
        ${Value},

        [switch]
        ${Force}
    )

    begin {
        try {
            $outBuffer = $null
            if ($PSBoundParameters.TryGetValue('OutBuffer', [ref] $outBuffer)) {
                $PSBoundParameters['OutBuffer'] = 1
            }

            $PSBoundParameters['ItemType'] = 'File'

            $wrappedCmd = $ExecutionContext.InvokeCommand.GetCommand('Microsoft.PowerShell.Management\New-Item', [System.Management.Automation.CommandTypes]::Cmdlet)
            $scriptCmd = { & $wrappedCmd @PSBoundParameters }

            $steppablePipeline = $scriptCmd.GetSteppablePipeline($myInvocation.CommandOrigin)
            $steppablePipeline.Begin($PSCmdlet)
        }
        catch {
            $PSCmdlet.ThrowTerminatingError($_)
        }
    }

    process {
        try {
            $steppablePipeline.Process($Value)
        }
        catch {
            $PSCmdlet.ThrowTerminatingError($_)
        }
    }

    end {
        try {
            $steppablePipeline.End()
        } catch {
            $PSCmdlet.ThrowTerminatingError($_)
        }
    }
    <#
    .ForwardHelpTargetName Microsoft.PowerShell.Management\New-Item
    .ForwardHelpCategory Cmdlet
    #>
}

[PSCustomObject]@{ Value = "Lorem ipsum" } | New-File .\BPN_value.txt -Force
"Lorem ipsum" | New-File .\BPN_value2.txt -Force

CodePudding user response：

It is possible if the values of the -Path or -Name parameter is also a property of the object in the pipeline:

[PSCustomObject]@{
    name = 'TestFile'
    value = 'Hello World'
} | New-Item

Console capture:

PS ScratchPad> [PSCustomObject]@{
>>     Name = 'TestFile'
>>     value = 'Hello World'
>> } | New-Item


    Directory: C:\ScratchPad


Mode                 LastWriteTime         Length Name
----                 -------------         ------ ----
-a----        11/23/2022  12:07 AM             35 TestFile

Or:

PS ScratchPad> [PSCustomObject]@{
>>     Path = "$Home\Documents\TestFile.txt"
>>     value = 'Hello World'
>> } | New-Item


    Directory: C:\Users\keith\Documents


Mode                 LastWriteTime         Length Name
----                 -------------         ------ ----
-a----        11/23/2022  12:27 AM             64 TestFile.txt

But for some reason, it doesn't like -Path -Name:

PS ScratchPad> [PSCustomObject]@{
>>     Path = "$Home\Documents"
>>     Name = 'TestFile'
>>     value = 'Hello World'
>> } | New-Item
New-Item : Access to the path 'C:\Users\keith\Documents' is denied.
At line:5 char:5
  } | New-Item
      ~~~~~~~~
      CategoryInfo          : PermissionDenied: (C:\Users\keith\Documents:String) [New
   -Item], UnauthorizedAccessException
      FullyQualifiedErrorId : NewItemUnauthorizedAccessError,Microsoft.PowerShell.Comm
   ands.NewItemCommand