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powershell/PSUseSingleValueFromPipelineParameter is a PSScriptAnalyzer diagnostic emitted by tally for PowerShell snippets embedded in Dockerfiles.
PropertyValue
SeverityWarning
CategoryPSScriptAnalyzer
Auto-fixNo

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Description

Parameter sets should have at most one parameter marked as ValueFromPipeline = true. This rule identifies functions where multiple parameters within the same parameter set have ValueFromPipeline set to true (either explicitly or implicitly).

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How

Ensure that only one parameter per parameter set accepts pipeline input by value. If you need multiple parameters to accept different types of pipeline input, use separate parameter sets.

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Examples

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Problematic code

function Process-Data {
    [CmdletBinding()]
    param(
        [Parameter(ValueFromPipeline)]
        [string] $InputData,

        [Parameter(ValueFromPipeline)]
        [string] $ProcessingMode
    )

    process {
        Write-Output "$ProcessingMode`: $InputData"
    }
}

​
Correct code

function Process-Data {
    [CmdletBinding()]
    param(
        [Parameter(ValueFromPipeline)]
        [string] $InputData,

        [Parameter(Mandatory)]
        [string] $ProcessingMode
    )
    process {
        Write-Output "$ProcessingMode`: $InputData"
    }
}

​
Suppression

To suppress this rule for a specific parameter set, use the SuppressMessage attribute with the parameter set name: 
function Process-Data {
    [Diagnostics.CodeAnalysis.SuppressMessage('PSUseSingleValueFromPipelineParameter', 'MyParameterSet')]
    [CmdletBinding()]
    param(
        [Parameter(ValueFromPipeline, ParameterSetName='MyParameterSet')]
        [string] $InputData,

        [Parameter(ValueFromPipeline, ParameterSetName='MyParameterSet')]
        [string] $ProcessingMode
    )
    process {
        Write-Output "$ProcessingMode`: $InputData"
    }
}
For the default parameter set, use 'default' as the suppression target: 
[Diagnostics.CodeAnalysis.SuppressMessage('PSUseSingleValueFromPipelineParameter', 'default')]

​
Notes

  • This rule applies to both explicit ValueFromPipeline = $true and implicit ValueFromPipeline (which is the same as using = $true)
  • Parameters with ValueFromPipeline=$false are not flagged by this rule
  • The rule correctly handles the default parameter set (__AllParameterSets) and named parameter sets
  • Different parameter sets can each have their own single ValueFromPipeline parameter without triggering this rule

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Source

This rule documentation is adapted from Microsoft’s PSScriptAnalyzer documentation for UseSingleValueFromPipelineParameter, licensed under CC BY 4.0.