Method invocation failed because [System.Management.Automation.PSObject] does not contain a method named 'op_Addition'

Question

I am trying to add together multiple variables together like the following:

$Var1 = Get-Mailbox-Identity "XXXXX" | select DisplayName
$Var2 = Get-Mailbox -Identity "XXXXX" | select PrimarySmtpAddress
$var3 = $var1 + $Var2

The error I get when doing this is:

Method invocation failed because [System.Management.Automation.PSObject] does not contain a method named 'op_Addition'.
At line:1 char:1
+ $var3 = $var1 + $Var2
+ ~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidOperation: (op_Addition:String) [], RuntimeException
    + FullyQualifiedErrorId : MethodNotFound

I know you could simply do:

$Var1 = Get-Mailbox -Identity "XXXXX" | Select-Object DisplayName,PrimarySmtpAddress

Any advice would be greatly appreciated.

Answer 1

You are getting a custom object as a return when you try to complete the command, you need to set ExpandProperty to get the actual value.

[STRING]$Var1 = Get-Mailbox -Identity "XXXXX" | Select-Object -ExpandProperty DisplayName

[STRING]$Var2 = Get-Mailbox -Identity "XXXXX" | Select-Object -ExpandProperty PrimarySmtpAddress

$var3 = $var1 + $Var2

Answer 2

It is not clear what you expect as result from the 'addition'. Indeed you cannot simply add two PSObjects together like you can with strings or arrays using +.

1) If what you need is for the two objects to be combined in an array then this would do it:

$result = @()
$result += Get-Mailbox -Identity "XXXXX" | Select-Object DisplayName
$result += Get-Mailbox -Identity "XXXXX" | Select-Object PrimarySmtpAddress

2) If the result you seek is a new object with the properties of two objects combined, something like the function below can help:

function Join-Properties {
    # combine the properties of two PSObjects and return the result as new object
    [CmdletBinding()]
    param (
        [Parameter(Mandatory = $true, Position = 0)]
        $ObjectA,

        [Parameter(Mandatory = $true, Position = 1)]
        $ObjectB,

        [switch] $Overwrite
    )
    if ($ObjectA -is [PSObject] -and $ObjectB -is [PSObject]) {
        # combine the properties of two PSObjects

        # get arrays of property names for both objects
        [string[]] $p1 = $ObjectA | Get-Member -MemberType Properties | Select-Object -ExpandProperty Name
        [string[]] $p2 = $ObjectB | Get-Member -MemberType Properties | Select-Object -ExpandProperty Name

        # or do it this way
        # [string[]] $p1 = $ObjectA.PSObject.Properties | Select-Object -ExpandProperty Name
        # [string[]] $p2 = $ObjectB.PSObject.Properties | Select-Object -ExpandProperty Name

        # if you do not want to overwrite common properties in in $ObjectA with the values from objectB
        if (!$Overwrite) { $p2 = $p2 | Where-Object { $p1 -notcontains $_ } }

        # create a new object with al properties of $ObjectA and add (or overwrite) the properties from $ObjectB to it.
        $Output = $ObjectA | Select-Object $p1
        foreach($prop in $p2) {
            Add-Member -InputObject $Output -MemberType NoteProperty -Name $prop -Value $ObjectB."$prop" -Force
        }

        # return the result
        $Output
    }
    else {
        Write-Warning "Only [PSObject] objects supported. Both input objects need to be of same type."
    }
}

Using your example on this:

$Var1 = Get-Mailbox -Identity "XXXXX" | select DisplayName
$Var2 = Get-Mailbox -Identity "XXXXX" | select PrimarySmtpAddress
$var3 = Join-Properties $Var1 $Var2

would yield a single PSObject with both properties DisplayName and PrimarySmtpAddress

DisplayName  PrimarySmtpAddress         
-----------  ------------------         
Cassius Clay Mohammed.Ali@yourdomain.com

Hope that helps