Function return value in PowerShell

Question

I have developed a PowerShell function that performs a number of actions involving provisioning SharePoint Team sites  Ultimately  I want the function to return the URL of the provisioned site as a String so at the end of my function I have the following code    rs    url ToString    return  rs    The code that calls this function looks like    returnURL   MyFunction -param 1       So I am expecting a String  however it s not  Instead  it is an object of type System Management Automation PSMethod  Why is it returning that type instead of a String type

User · Answer

As a workaround I ve been returning the last object in the array that you get back from the function    It is not a great solution  but it s better than nothing   someFunction       a    hello      Function is running     return  a     b   someFunction  b    b   b count - 1      Or  b    b -1                 Simpler   All in all  a more one-lineish way of writing the same thing could be    b    someFunction  someParameter  andAnotherOne  -1

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Luke s description of the function results in these scenarios seems to be right on  I only wish to understand the root cause and the PowerShell product team would do something about the behavior  It seems to be quite common and has cost me too much debugging time   To get around this issue I ve been using global variables rather than returning and using the value from the function call   Here s another question on the use of global variables  Setting a global PowerShell variable from a function where the global variable name is a variable passed to the function

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PowerShell has really wacky return semantics - at least when viewed from a more traditional programming perspective  There are two main ideas to wrap your head around    All output is captured  and returned The return keyword really just indicates a logical exit point   Thus  the following two script blocks will do effectively the exact same thing    a    Hello  World  return  a        a    Hello  World   a return   The  a variable in the second example is left as output on the pipeline and  as mentioned  all output is returned  In fact  in the second example you could omit the return entirely and you would get the same behavior  the return would be implied as the function naturally completes and exits    Without more of your function definition I can t say why you are getting a PSMethod object  My guess is that you probably have something a few lines up that is not being captured and is being placed on the output pipeline   It is also worth noting that you probably don t need those semicolons - unless you are nesting multiple expressions on a single line    You can read more about the return semantics on the about Return page on TechNet  or by invoking the help return command from PowerShell itself

User · Answer

The following simply returns 4 as an answer  When you replace the add expressions for strings it returns the first string   Function StartingMain      a   1   3    b   2   5    c   3   7   Return  a    Function StartingEnd  b      Write-Host  b    StartingEnd StartingMain    This can also be done for an array  The example below will return  Text 2   Function StartingMain      a       Text 1   Text 2   Text 3     Return  a    Function StartingEnd  b      Write-Host  b 1     StartingEnd StartingMain    Note that you have to call the function below the function itself  Otherwise  the first time it runs it will return an error that it doesn t know what  StartingMain  is

User · Answer

I pass around a simple Hashtable object with a single result member to avoid the return craziness as I also want to output to the console  It acts through pass by reference   function sample-loop  returnObj      for  i   0   i -lt 10   i          Write-Host  loop counter   i       returnObj result          function main-sample        countObj      result   0     sample-loop -returnObj  countObj   Write-Host                   Write-Host  Total       countObj result     main-sample   You can see real example usage at my GitHub project unpackTunes

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It s hard to say without looking at at code  Make sure your function doesn t return more than one object and that you capture any results made from other calls  What do you get for      returnURL  count   Anyway  two suggestions   Cast the object to string       return  string  rs   Or just enclose it in double quotes  same as above but shorter to type       return   rs

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The existing answers are correct  but sometimes you aren t actually returning something explicitly with a Write-Output or a return  yet there is some mystery value in the function results  This could be the output of a builtin function like New-Item  PS C  temp gt  function ContrivedFolderMakerFunction    gt  gt      folderName    DateTime   Now ToFileTime    gt  gt      folderPath   Join-Path -Path   -ChildPath  folderName  gt  gt     New-Item -Path  folderPath -ItemType Directory  gt  gt     return  true  gt  gt    PS C  temp gt   result   ContrivedFolderMakerFunction PS C  temp gt   result       Directory  C  temp   Mode                LastWriteTime         Length Name ----                -------------         ------ ---- d-----         2 9 2020   4 32 PM                132257575335253136 True   All that extra noise of the directory creation is being collected and emitted in the output  The easy way to mitigate this is to add   Out-Null to the end of the New-Item statement  or you can assign the result to a variable and just not use that variable  It would look like this     PS C  temp gt  function ContrivedFolderMakerFunction    gt  gt      folderName    DateTime   Now ToFileTime    gt  gt      folderPath   Join-Path -Path   -ChildPath  folderName  gt  gt     New-Item -Path  folderPath -ItemType Directory   Out-Null  gt  gt       -or-  gt  gt      throwaway   New-Item -Path  folderPath -ItemType Directory   gt  gt     return  true  gt  gt    PS C  temp gt   result   ContrivedFolderMakerFunction PS C  temp gt   result True   New-Item is probably the more famous of these  but others include all of the StringBuilder Append    methods  as well as the SqlDataAdapter Fill   method

User · Answer

This part of PowerShell is probably the most stupid aspect  Any extraneous output generated during a function will pollute the result  Sometimes there isn t any output  and then under some conditions there is some other unplanned output  in addition to your planned return value   So  I remove the assignment from the original function call  so the output ends up on the screen  and then step through until something I didn t plan for pops out in the debugger window  using the PowerShell ISE    Even things like reserving variables in outer scopes cause output  like  boolean  isEnabled which will annoyingly spit a False out unless you make it  boolean  isEnabled    false   Another good one is  someCollection Add  thing   which spits out the new collection count

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With PowerShell 5 we now have the ability to create classes  Change your function into a class  and return will only return the object immediately preceding it  Here is a real simple example   class test class        int return what             Write-Output  Hello  World           return 808979          tc   New-Object -TypeName test class  tc return what     If this was a function the expected output would be   Hello World 808979   but as a class the only thing returned is the integer 808979  A class is sort of like a guarantee that it will only return the type declared or void

[powershell] Function return value in PowerShell

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