UseSingleValueFromPipelineParameter

Severity Level: Warning

Default state: Disabled

Description

This rule detects functions where multiple parameters within the same parameter set are marked as accepting pipeline input by value. Parameter sets should have at most one parameter with ValueFromPipeline = true.

When you need multiple parameters to accept different types of pipeline input, use separate parameter sets instead. Each parameter set can have its own single ValueFromPipeline parameter, but you can't have more than one within the same parameter set.

Example

Noncompliant

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

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

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

Compliant

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

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

Configure rule

Rules = @{
    PSUseSingleValueFromPipelineParameter  = @{
        Enable = $true
    }
}

Parameters

Enable

This parameter controls whether ScriptAnalyzer checks the code against this rule. It accepts a boolean value. To enable this rule, set this parameter to $true. The default value is $false.

Suppression

This rule is disabled by default. If you have enabled it in your configuration but want to suppress it for a specific function, you can use the SuppressMessage attribute:

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).
• This rule doesn't flag parameters with ValueFromPipeline = $false.
• 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.