I need help understanding how to pass on an argument from an imported module.
The module contains some custom arguments such as -one, -two, -three
I am trying to make a GUI using the commands from the module.
eg. If "One" is selected from the drop down menu, pass through the -one command.
However when I do so (using the example below), I get the error: "A positional parameter cannot be found that accepts argument '-one'."
I can see that using the code below, it adds single quotations around the command which probably breaks it.
I know I can run an IF statement (eg if combobox.text = "one", do this), however I would prefer to use a variable instead of having to make multiple if statements or a loop. The use of a variable seems like a simpler option.
I'm learning this language as I go so I'm not quite there yet with the knowledge :)
Thanks for any help. Hope this made sense.
$variable = $comboboxNumbers.Text
#example One is selected from the dropdown
Custom-ADCommand -identity "username" $variable
Below is simple example method:
function Set-SwitchParams {
[CmdletBinding()]
param (
# Parameter help description
[Parameter(Mandatory = $false)]
[switch]
$SwitchA,
[Parameter(Mandatory = $false)]
[switch]
$SwitchB
)
begin {
}
process {
}
end {
if ($SwitchA){
Write-Host "SwitchA is activated"
}
if ($SwitchB){
Write-Host "SwitchB is activated"
}
}
}
Put the method in a PS1 file, e.g. SwitchPlayground.ps1. Then source the file in PowerShell via:
. .\SwitchPlayground.ps1
Afterward, you can play around with the command, e.g.:
Set-SwitchParmas -SwitchA
I'd suggest studying the following links:
about functions basic
about functions advanced
about function parameters
Hope that helps.
An If statement if probably much nicer, but its possible to create a string and then execute the string in powershell.
As a simple example take this string
$string = '#("test","hello","whats up")'
I can then execute it and use it to create an array
$array = invoke-expression $string
Which will create an array with "test", "hello" and "whats up" and store it in $array
PS C:\temp> $string = '#("test","hi","what")'
PS C:\temp> $array = Invoke-Expression $string
PS C:\temp> $array
test
hi
what
Related
i m writing a script that makes use of a cmdlet from a console app, let's call the cmdlet as cmdA. I have no control over implementation of cmdA. cmdA takes parameters with a double dash (cmdA --param1 value1 --param2 value2 --param3 value3 --param4 value4 --param5 value5)
Now param2, param3, param4 and param5 are optional. The user of my script may or may not provide values for these optional parameters. In the script, i formed a hashtable using the parameters for which the user provided values. Let's call it paramHashtable.
I am executing cmdA #paramHashtable but this is not working. I think it has to do something with double dashes because this approach works fine with a cmd that takes parameters with single dash
What would be an efficient way to pass parameters to the cmdA (an inefficient way would be to use many if blocks to check which values were provided and make calls accordingly)
edited*
This is how i m creating the hashtable :-
$optionalParameters = #{}
$optionalParameters = ParameterSelection ${OutputFolder} ${PerfQueryIntervalInSec} ${StaticQueryIntervalInSec} ${NumberOfIterations}
$requiredParameters = #{"sqlConnectionStrings " = "$SqlConnectionStrings"}
$parameters = $requiredParameters + $optionalParameters
function ParameterSelection ([string] $outputFolder, [string] $perfQueryIntervalInSec, [string] $staticQueryIntervalInSec, [string] $numberOfIterations)
{
$parametersList = #{}
if($outputFolder -ne "")
{
$parametersList["outputFolder "] = $outputFolder
}
if($perfQueryIntervalInSec -ne "")
{
$parametersList["perfQueryIntervalInSec "] = $perfQueryIntervalInSec
}
if($staticQueryIntervalInSec -ne "")
{
$parametersList["staticQueryIntervalInSec "] = $staticQueryIntervalInSec
}
if($numberOfIterations -ne "")
{
$parametersList["numberOfIterations "] = $numberOfIterations
}
return $parametersList
}
This is how i m calling it :-
& $ExePath actionName #parameters
The $ExePath has the path of the program to be executed
The actionName takes parameters like this:-
actionName --sqlConnectionStrings "Data Source=Server1" --outputFolder C:\Output
Can splatting with hash table work on cmdlets / functions where it's parameter have dashes?
It may work, but it is definitely not a good idea to have parameter names with dashes as this will result in a function / cmdlet where named parameters cannot be used, PowerShell binds the arguments positionally! (thanks mklement0 for pointing this out):
function Test-Splatting {
param(${-param1}, ${-param2})
"${-param1} ${-param2}"
}
$param = #{ '--param1' = 'hello'; '--param2' = 'world' }
Test-Splatting #param # => hello world
Example of what was mentioned before using the same function above:
# --param1 is bound positionally and not interpreted as a parameter:
Test-Splatting --param1 hello # => --param1 hello
As for an external programs, the linked answer in comments explains very well the approach you could take using a wrapper function and the use of the automatic variable $args:
function myfunc {
$binaryPath = 'path/to/file.exe'
& $binaryPath actionName $args
# or #args we can't be sure until testing
}
myfunc --sqlConnectionStrings "Data Source=Server1" --outputFolder C:\Output
As noted in the comments, because you are calling an external program, you should use array-based splatting or simply arrays directly to pass programmatically constructed arguments.
By contrast, hashtable-based splatting is usually only helpful when calling PowerShell commands (while it technically works with external programs too, the resulting parameter format (e.g. -foo:bar or -foo:"bar none") is unusual and understood by few external programs)
Note that the parameter names and values must be passed as separate array elements and the elements representing parameter names must include the - or -- prefix; e.g., consecutive array elements
'--sqlConnectionStrings' (the name) and
'Data Source=Server1' (the value).
PowerShell then constructs a command line for invocation of the external program behind the scenes, space-separating the array elements and double-quoting elements with embedded spaces on demand; the above example turns into the following:
--sqlConnectionStrings "Data Source=Server1"
Note that it is up to the target program to parse the single string that is its command line in a way that recognizes parameter name-value pairs.
# Get the array of *optional* parameter names and values from your helper function.
$optionalParameters = ParameterSelection ${OutputFolder} ${PerfQueryIntervalInSec} ${StaticQueryIntervalInSec} ${NumberOfIterations}
# Declare the *required* parameter(s) as an array.
$requiredParameters = '--sqlConnectionStrings', $SqlConnectionStrings
# Pass the arrays as-is to the external program.
# (Empty arrays are effectively ignored.)
& $ExePath actionName $requiredParameters $optionalParmeters
Your ParameterSelection function can be simplified as follows:
function ParameterSelection ([string] $outputFolder, [string] $perfQueryIntervalInSec, [string] $staticQueryIntervalInSec, [string] $numberOfIterations)
{
# Loop over all bound parameters.
$PSBoundParameters.GetEnumerator() | ForEach-Object {
# Emit the parameter name prefixed with '--' and the value.
# PowerShell automatically collects the output strings in an array
# when you assign a call to this function to a variable.
'--' + $_.Key
$_.Value
}
}
I am trying to get a value from an input box from a Powershell script back to a UI Path Sequence. I have created a simple sequence as an example. Yes, I know I could do this all in UI Path, I am just using an easy example as a way to try and test this for future use cases. Here is my sequence:
My text file from "Read text file" is:
$test = "Desktop/PassingArgs2of2.ps1 -Message foo"
Invoke-Expression -Command $test
The activity in UiPath looks like so:
The psCmd that I am running in the Invoke power shell activity looks like this:
Param(
[parameter(Mandatory=$true)]
[string]
$Message)
try{
$Global:fooVar = $null
function Test-InputBox(){
[void][Reflection.Assembly]::LoadWithPartialName('Microsoft.VisualBasic')
$msg = "fooMsg"
$title = "fooTitle"
$localtest = [Microsoft.VisualBasic.Interaction]::InputBox($msg, $title)
$Global:fooVar = $localtest.ToString()
}
Test-InputBox
}
catch{}
I tried setting fooVar equal to testLocal in the PowerShellVariables within Invoke power shell and then writing it, but that did not work.
Basically I want to get fooVar back into UI Path. Any help would be greatly appreciated. Thank you!
You're almost there. First, your Powershell script has to return a value. Take this for example:
[void][Reflection.Assembly]::LoadWithPartialName('Microsoft.VisualBasic')
$title = 'Your title goes here'
$msg = 'Your favorite color:'
$text = [Microsoft.VisualBasic.Interaction]::InputBox($msg, $title)
return $text
Here's the script in action (note that I called it twice and provided "red" the first time:
Then, just use this script directly in the Invoke Powershell activity. Note that the most important part here is the Output property - here, I decided to go for an array of strings. Naturally, as we only return a single value, you can just access the text provided by the user by accessing output(0).ToString().
I can write the following code in javascript:
function sum(num1, num2) {
return num1 + num2;
}
and then get a value
var someNum = sum(2,5);
I would like to do the same thing in Powershell, but I read the following guide:
PowerShell also knows the return keyword; however, it follows a
different logic. In general, the purpose of return is to end the
execution of a code section and to give the control back to the parent
block.
If you add a parameter to the return statement, the value will indeed
be returned to the calling subroutine. However, this also applies for
all other statements with an output. This means that any output
produced in the function will be stored in the variable together with
the return parameter.
I want to do this for the sake of having pure functions. However, it seems doing
var someNum = sum(2,5);
is entirely redundant, when I can just call the function above, define someNum inside of it, and it will be available in the global scope.
Am I missing something or is it possible to write pure functions in Powershell that don't return everything inside the function?
A bit tangential, but here is my actual code:
function GetPreviousKeyMD5Hashes() {
$query = "SELECT Name, MD5, executed FROM [AMagicDb].[dbo].cr_Scripts";
$command = New-Object System.Data.SQLClient.SQLCommand;
$command.Connection = $connection;
$command.CommandText = $query;
try {
$reader = $command.ExecuteReader();
while ($reader.Read()) {
$key = $reader.GetString(1)
$previousScripts.Add($key) | Out-Null
}
$reader.Close();
Write-Output "$(Get-Date) Finished querying previous scripts"
}
catch {
$exceptionMessage = $_.Exception.Message;
Write-Output "$(Get-Date) Error running SQL at with exception $exceptionMessage"
}
}
and then:
$previousScripts = New-Object Collections.Generic.HashSet[string];
GetPreviousKeyMD5Hashes;
This code isn't clear to me at all - running GetPreviousKeyMD5Hashes does set $previousScripts, but this is entirely unclear to whoever modifies this after me. My only other alternative (afaik) is to have all this in line, which also isn't readable.
is entirely redundant, when I can just call the function above, define someNum inside of it, and it will be available in the global scope.
No: functions execute in a child scope (unless you dot-source them with .), so variables created or assigned to inside a function are local to it.
Am I missing something or is it possible to write pure functions in Powershell that don't return everything inside the function?
Yes: The implicit output behavior only applies to statements whose output is neither captured - $var = ... - nor redirected - ... > foo.txt
If there are statements that happen to produce output that you'd like to discard, use $null = ... or ... > $null
Note: ... | Out-Null works in principle too, but will generally perform worse, especially in earlier PowerShell versions - thanks, TheIncorrigible1.
If there are status messages that you'd like to write without their becoming part of the output, use Write-Host or, preferably Write-Verbose or, in PSv5+, Write-Information, though note that the latter two require opt-in for their output to be visible in the console.
Do NOT use Write-Output to write status messages, as it writes to the success output stream, whose purpose is to output data ("return values").
See this answer of mine for more information about PowerShell's output streams.
The equivalent of your JavaScript code is therefore:
function sum($num1, $num2) {
Write-Host "Adding $num1 and $num2..." # print status message to host (console)
$num1 + $num2 # perform the addition and implicitly output result
}
PS> $someNum = sum 1 2 # NOTE: arguments are whitespace-separated, without (...)
Adding 1 and 2... # Write-Host output was passed through to console
PS> $someNum # $someNum captured the success output stream of sum()
3
Am I missing something or is it possible to write pure functions in Powershell that don't return everything inside the function?
You can't have your cake and eat it too...
If you have no out put in your function, then it is "pure" like you desire. If you have output, that also becomes part of the return.
You can use [ref] params. See below for example.
function DoStuff([ref]$refObj)
{
Write-Output "DoStuff: Enter"
$refObj.Value += $(1 + 2)
$refObj.Value += "more strings"
Write-Output "DoStuff: Exit"
}
$refRet = #()
$allRet = DoStuff([ref]$refRet)
"allRet"
$allRet
"refRet"
$refRet
"`n`nagain"
$allRet = DoStuff([ref]$refRet)
"allRet"
$allRet
"refRet"
$refRet
Note: Powershell doesn't need semicolons at the end of each statement; only for separating multiple statements on the same line.
Whenever possible, it's a good idea to avoid changing global state within a function. Pass input as parameters, and return the output, so you aren't tied to using the function in only one way. Your sample could look like this:
function sum
{
param($num1,$num2)
return $num1+$num2
}
$somenum=sum 2 5
Now, with Powershell, the return statement isn't needed. The result of every statement that isn't otherwise assigned, captured, redirected, or otherwise used, is just thrown in with the return value. So we could replace the return statement above with simply
$num1+$num2
You're already making use of this in your code with:
$previousScripts.Add($key) | Out-Null
where you are discarding the result of .Add(). Otherwise it would be included in the return value.
Personally, I find using return to explicitly mark the return value makes it easier to read. Powershell's way of putting all if the output in the return caused a lot of trouble for me as I was learning.
So, the only fixes to your code I would make are:
Move $previousScripts = New-Object Collections.Generic.HashSet[string] to inside the function, making it local.
Add return $previousScripts to the end of the function.
Preface: I know PS can multithread in many different ways, my question is whether there is a syntax that allows PowerShell to access the ForEach (and For) methods in System.Threading.Tasks.Parallel. For example, I have the following very simple c# example where list:
Parallel.ForEach(
list,
(x) =>
{
Console.WriteLine("Thread {0} has {1}", Thread.CurrentThread.ManagedThreadId, x);
});
Now I have been trying to find the right syntax to rewrite in PowerShell. I put my code in a scriptblock. It seems I can't figure out how to replace the lambda syntax, normally calling &$scriptblock is the way this is done. The following is one of many variations I have tried:
$thread = [System.Threading.Thread]
$parallel = [System.Threading.Tasks.Parallel]
$scriptblock = {param($x) Write-Host("Thread {0} has {1}" -f
$thread::CurrentThread.ManagedThreadId, $x)}
$parallel::ForEach(
$list,
($x),
{
&$scriptblock -item $x
})
Is there a way to get the Parallel.ForEach to work in PowerShell?
Is there an easy way to parse the params from a powershell script file
param(
[string]$name,
[string]$template
)
I have started reading the file and wondered if there is a better way, maybe by a help/man command?
class PowerShellParameter {
public string Name;
public string Type;
public string Default;
}
string[] lines = File.ReadAllLines(path);
bool inparamblock = false;
for (int i = 0; i < lines.Length; i++) {
if (lines[i].Contains("param")) {
inparamblock = true;
} else if (inparamblock) {
new PowerShellParameter(...)
if (lines[i].Contains(")")) {
break;
}
}
}
There are at least two possibilies. First one (imho better): use Get-Command:
# my test file
#'
param(
$p1,
$p2
)
write-host $p1 $p2
'# | Set-content -path $env:temp\sotest.ps1
(Get-Command $env:temp\sotest.ps1).parameters.keys
For all members look at
Get-Command $env:temp\sotest.ps1 | gm
#or
Get-Command $env:temp\sotest.ps1 | fl *
The other (harder way) is to use regular expression
[regex]::Matches((Get-Help $env:temp\sotest.ps1), '(?<=\[\[-)[\w]+') | select -exp Value
I like the solution with Get-Command proposed by #stej. Unfortunately it does not work if script parameters have explicit types specified and an assembly of such a type is not yet loaded into the session. That is why I still use this script: Get names of script parameters
I'm not really sure what you're after, is it documenting your scripts? In that case have a look at Get-Help about_Comment_Based_Help. It will tell you how to do that, and after that you can use Get-Help on your script/module.
If you're after more strict parameter handling, take a look at about_functions_advanced_parameters and about_functions_cmdletbindings on how to better structure parameters. For example,
[Parameter(Position=0,Mandatory=$true,HelpMessage='Enter
architecture("OSX","WinXP","Win7","Linux")')]
[ValidateSet("OSX","WinXP","Win7","Linux")]
[string]$architecture
will make that parameter mandatory, read from position 0 of the command, allow only a value from the given set, and give a brief help message when asking for input if that parameter was not given.