How could I print out a debug message in PowerShell cmdlet but not WriteObject as return value?

Question

I try to build a PowerShell cmdlet with C#. In a function, I want to print one line log and return an object. If in both place I use WriteObject(), I could see them in the PowerShell window. But if I use a variable to get the output my cmdlet, it gets both the string and object. How could I let the variable only get the object I'm about to return?

e.g.

public override void ExecuteCmdlet()
{
    Dictionary<string, string> returnValue = new Dictionary<string, string>();
    WriteObject("Debug Log"); // Print log

    // ... do something ...

    WriteObject(returnValue); // Return value
}

Assume my cmdlet named foo. In PowerShell window, if I run

$ret = foo
$ret.Count

The output is 2.

$ret

The output contains both the debug message and the dictionary. Any idea to let $ret contains the dictionary?

Thanks!

Mathias R. Jessen · Accepted Answer · 2016-08-18 20:52:14Z

2

Use WriteDebug() to write to the Debug stream:

public override void ExecuteCmdlet()
{
    Dictionary<string, string> returnValue = new Dictionary<string, string>();
    WriteDebug("Debug Log"); // Print log

    // ... do something ...

    WriteObject(returnValue); // Return value
}

PS C:\> @(foo).Count
1
PS C:\> $DebugPreference = 'Continue' # show debug output, but don't halt exection
PS C:\> @(foo).Count
Debug Log
1
PS C:\> $ret = foo
Debug Log
PS C:\> $ret.Count
1

Note: you could also write to the Verbose stream (WriteVerbose()), if the purpose is to passively provide diagnostic output without necessarily interrupting execution

edited Aug 18, 2016 at 20:52

answered Aug 18, 2016 at 20:45

Mathias R. Jessen

178k13 gold badges175 silver badges234 bronze badges

Sign up to request clarification or add additional context in comments.

5 Comments

NonStatic Over a year ago

WriteDebug and WriteVerbose needs additional parameter when using cmdlet. Is there anyway to get the output without the -Verbose or -Debug?

Mathias R. Jessen Over a year ago

Not without polluting the output. Do you get any errors? Cmdlet.WriteDebug and Cmdlet.WriteVerbose shouldn't require anything more that the message text?

NonStatic Over a year ago

No errors, just no output if I don't turn on the debug output or without -Debug. I'd like to let me user do not need any further steps and no more parameters and then get the message which is not included in the output object.

NonStatic Over a year ago

Alright, I'm going to use WriteVerbose(), which will not need to ask for additional commands/statements, just -vb in the parameter list. Thanks!

FSCKur Over a year ago

Actually... you can set VerbosePreference. The effect of the user providing -Verbose is to set VerbosePreference inside the cmdlet. You can set it directly.

Collectives™ on Stack Overflow

How could I print out a debug message in PowerShell cmdlet but not WriteObject as return value?

1 Answer 1

5 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

5 Comments

Your Answer

Sign up or log in

Post as a guest

Related