Return array with single element in PowerShell

问题

This should be very simple - I need to return an array of hashtables from a function. This works when there is more than one hashtable, but when there is only one then the result is not an array. I'd rather not test if the result is an array or not.

function GetArrayWith1Hashtable()
{
    $array = @()

    $hashtable = @{}
    $hashtable["a"] = "a" 
    $hashtable["b"] = "b" 
    $hashtable["c"] = "c"
    $array += $hashtable 

    Write-Host "GetArrayWith1Hashtable array.Length =" $array.Length
    Write-Host "GetArrayWith1Hashtable array.Count" $array.Count
    Write-Host "GetArrayWith1Hashtable array[0].Keys" $array[0].Keys

    $array
}

function GetArrayWith2Hashtables()
{
    $array = @()

    $hashtable = @{}
    $hashtable["a"] = "a" 
    $hashtable["b"] = "b" 
    $hashtable["c"] = "c"
    $array += $hashtable 

    $hashtable2 = @{}
    $hashtable2["d"] = "d" 
    $hashtable2["e"] = "e"
    $hashtable2["f"] = "f"
    $array += $hashtable2 

    Write-Host "GetArrayWith2Hashtables array.Length = " $array.Length
    Write-Host "GetArrayWith2Hashtables array.Count = " $array.Count
    Write-Host "GetArrayWith2Hashtables array[0].Keys =" $array[0].Keys
    Write-Host "GetArrayWith2Hashtables array.Count = "$array[1].Keys

    $array
}

$result1 = GetArrayWith1Hashtable
# $result1.Length - not available
Write-Host "Result of GetArrayWith1Hashtable result1.Count = " $result1.Count                      # Count = 2 (would expect this to be 1)
# $result1[0] not available - not an array

$result2 = GetArrayWith2Hashtables
Write-Host "Result of GetArrayWith2Hashtables result2.Length = "    $result2.Length # Length = 2
Write-Host "Result of GetArrayWith2Hashtables result2.Count = "     $result2.Count # Count = 2
Write-Host "Result of GetArrayWith2Hashtables result2[0].Keys = "     $result2[0].Keys # Keys = c a b
Write-Host "Result of GetArrayWith2Hashtables result2[1].Keys = "     $result2[1].Keys # Keys = d e f

 <#
  FULL OUTPUT:

 GetArrayWith1Hashtable array.Length = 1
 GetArrayWith1Hashtable array.Count 1
 GetArrayWith1Hashtable array[0].Keys c a b

 Result of GetArrayWith1Hashtable result1.Count =  2

 GetArrayWith2Hashtables array.Length =  2
 GetArrayWith2Hashtables array.Count =  2
 GetArrayWith2Hashtables array[0].Keys = c a b
 GetArrayWith2Hashtables array.Count =  d e f

 Result of GetArrayWith2Hashtables result2.Length =  2
 Result of GetArrayWith2Hashtables result2.Count =  2
 Result of GetArrayWith2Hashtables result2[0].Keys =  c a b
 Result of GetArrayWith2Hashtables result2[1].Keys =  d e f

 #>

回答1:

Just cast the return type to an array:

$result1 = @(GetArrayWith1Hashtable)

回答2:

Actually you would only add a comma in front of your returned item like so. This tells PowerShell to return it as is without trying to be smart about it. This also allows you to fix it in one place and not everywhere it was being called.

function GetArrayWith1Hashtable()
{
    $array = @()

    $hashtable = @{}
    $hashtable["a"] = "a" 
    $hashtable["b"] = "b" 
    $hashtable["c"] = "c"
    $array += $hashtable 

    Write-Host "GetArrayWith1Hashtable array.Length =" $array.Length
    Write-Host "GetArrayWith1Hashtable array.Count" $array.Count
    Write-Host "GetArrayWith1Hashtable array[0].Keys" $array[0].Keys

    # The only edit was to add the comma below
    ,$array
}

来源：https://stackoverflow.com/questions/41997967/return-array-with-single-element-in-powershell

标签

arrays

powershell

hashtable

powershell-5.0