How to handle powershell Advanced function ErrorAction parameter?

Question

How can I properly use ErrorAction parameter with my Advanced function? For instance I have such function:

function test1 {
[CmdletBinding()]
param([string]$path = "c:\temp")

$src = Join-Path $path "src"
$dest = Join-Path $path "dest"

Copy-Item -Path $src $dest -Recurse -Verbose
write "SomeText"
}

Lets assume the source path $src does not exist. And I am executing this function with ErrorAction = Stop:

test1 -ea stop

I expect that the error will be thrown and I will not see "SomeText" message. But I got it:

Copy-Item : Cannot find path 'C:\temp\src' because it does not exist.
At line:5 char:1
+ Copy-Item -Path $path\src $path\dest -Recurse -Verbose
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : ObjectNotFound: (C:\temp\src:String) [Copy-Item], ItemNotFoundException
    + FullyQualifiedErrorId : PathNotFound,Microsoft.PowerShell.Commands.CopyItemCommand

SomeText

I could add ErrorAction parameter to Copy-Item cmdlet inside the test1 function, but I want to be able to explicitly set it to the function to enable/disable error action behavior.

What should I do to make it work?

Unable to reproduce this behavior. Which version of PowerShell is this? Does it make a difference if you use the full parameter name (test1 -ErrorAction Stop)? — Mathias R. Jessen
– Mathias R. Jessen, Commented Aug 4, 2016 at 9:34
I discovered that w/o Verbose parameter added to Copy-Item it works fine (stops straight after the error). But with Verbose parameter it does not work. PowerShell v.5 — Artem Bokov
– Artem Bokov, Commented Aug 4, 2016 at 9:59
Hmm explicit preference variables must prevent automatic passing... helpful. Good catch. — Chris Dent
– Chris Dent, Commented Aug 4, 2016 at 10:08

smichaud · Accepted Answer · 2016-08-04 12:19:47Z

2

You need to use $PSBoundParameters and alos check $ErrorActionPreference

function test1 {
    [CmdletBinding()]
    param([string]$path = "c:\temp")

    $src = Join-Path $path "src"
    $dest = Join-Path $path "dest"

    $errorAction = $PSBoundParameters["ErrorAction"]
    if(-not $errorAction){
        $errorAction = $ErrorActionPreference
    }


    Copy-Item -Path $src $dest -Recurse -Verbose -ErrorAction $errorAction
    write "SomeText"
}

$ErrorActionPreference = 'Stop'
test1

$ErrorActionPreference = 'continue'
test1 -ErrorAction Stop

answered Aug 4, 2016 at 12:19

smichaud

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1 Comment

c z Over a year ago

You should not consult $PSBoundParameters["ErrorAction"] (as evidenced from how messy this is!), when [CmdletBinding()] is present, the parameter is already applied to $ErrorActionPreference. Also, as part of CmdletBinding, you do not need to forward this to nested function calls, this is already done.

Kirill Pashkov · Accepted Answer · 2016-08-04 12:01:48Z

0

I would suggest you to place validation events for input parameters instead, like this:

param([ValidateScript({Test-Path $_})][string]$path = "c:\temp")

answered Aug 4, 2016 at 12:01

Kirill Pashkov

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Comments

c z · Accepted Answer · 2024-08-20 09:18:05Z

0

Handling is via Write-Error:

    function test1 {
        [CmdletBinding()]
        param()
        Write-Error "blah blah blah"
    }

Write-Error will throw when $ErrorActionPreference is Stop, ask the user for Inquire, print and continue for Continue, etc. etc.

More advanced handling is via:

throw, which will, by contrast, always halt execution.
$ErrorActionPreference, which holds the current state of the cascading -ErrorAction value.

answered Aug 20, 2024 at 9:18

c z

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