UseProcessBlockForPipelineCommand.md

description	Use process block for command that accepts input from pipeline.
ms.custom	PSSA v1.21.0
ms.date	06/28/2023
ms.topic	reference
title	UseProcessBlockForPipelineCommand

UseProcessBlockForPipelineCommand

Severity Level: Warning

Description

Functions that support pipeline input should always handle parameter input in a process block. Unexpected behavior can result if input is handled directly in the body of a function where parameters declare pipeline support.

Example

Wrong

Function Get-Number
{
    [CmdletBinding()]
    Param(
        [Parameter(ValueFromPipeline)]
        [int]
        $Number
    )

    $Number
}

Result

PS C:\> 1..5 | Get-Number
5

Correct

Function Get-Number
{
    [CmdletBinding()]
    Param(
        [Parameter(ValueFromPipeline)]
        [int]
        $Number
    )

    process
    {
        $Number
    }
}

Result

PS C:\> 1..5 | Get-Number
1
2
3
4
5