How can you test if an object has a specific property?

Question

How can you test if an object has a specific property?

Appreciate I can do ...

$members = Get-Member -InputObject $myobject 

and th

Answer 1

Real similar to a javascript check:

foreach($member in $members)
{
    if($member.PropertyName)
    {
        Write $member.PropertyName
    }
    else
    {
        Write "Nope!"
    }
}

Answer 2

For me MyProperty" -in $MyObject.PSobject.Properties.Name didn't work, however

$MyObject.PSobject.Properties.Name.Contains("MyProperty")

works

Answer 3

Just check against null.

($myObject.MyProperty -ne $null)

If you have not set PowerShell to StrictMode, this works even if the property does not exist:

$obj = New-Object PSObject;                                                   
Add-Member -InputObject $obj -MemberType NoteProperty -Name Foo -Value "Bar";
$obj.Foo; # Bar                                                                  
($obj.MyProperty -ne $null);  # False, no exception

Answer 4

I ended up with the following function ...

function HasNoteProperty(
    [object]$testObject,
    [string]$propertyName
)
{
    $members = Get-Member -InputObject $testObject 
    if ($members -ne $null -and $members.count -gt 0) 
    { 
        foreach($member in $members) 
        { 
            if ( ($member.MemberType -eq "NoteProperty" )  -and `
                 ($member.Name       -eq $propertyName) ) 
            { 
                return $true 
            } 
        } 
        return $false 
    } 
    else 
    { 
        return $false; 
    }
}

Answer 5

Like this?

 [bool]($myObject.PSobject.Properties.name -match "myPropertyNameToTest")

Answer 6

I recently switch to set strict-mode -version 2.0 and my null tests failed.

I added a function:

#use in strict mode to validate property exists before using
function exists {
  param($obj,$prop)
  try {
    if ($null -ne $obj[$prop]) {return $true}
    return $false
  } catch {
    return $false
  }
  return $false
}

Now I code

if (exists $run main) { ...

rather than

if ($run.main -ne $null) { ...

and we are on our way. Seems to work on objects and hashtables

As an unintended benefit it is less typing.