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 then foreach through the  members  but is there a function to test if the object has a specific property   Additional Info   The issue is I m importing two different sorts of CSV file  one with two columns  the other with three  I couldn t get the check to work with  Property   only with  NoteProperty      whatever the difference is  if     member MemberType -eq  NoteProperty    -and   member Name -eq  propertyName

User · Answer

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.

User · Answer

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

User · Answer

Just to clarify given the following object   Object   With the following properties  type          message user          john doe company com text           ts            11 21 2016 8 59 30 PM   The following are true   Object text -eq  NULL  Object NotPresent -eq  NULL  -not  Object text -not  Object NotPresent   So the earlier answers that explicitly check for the property by name is the most correct way to verify that that property is not present

User · Answer

For me MyProperty  -in  MyObject PSobject Properties Name didn t work  however   MyObject PSobject Properties Name Contains  MyProperty     works

User · Answer

Try this for a one liner that is strict safe   bool  myobject PSObject Properties  propertyName   For example  Set-StrictMode -Version latest   propertyName    Property1    myobject    PSCustomObject    Property0    Value0      if   bool  myobject PSObject Properties  propertyName          value    myobject  propertyName

User · Answer

I ve been using the following which returns the property value  as it would be accessed via  thing  prop  if the  property  would be to exist and not throw a random exception  If the property  doesn t exist   or has a null value  then  null is returned  this approach functions in is useful for strict mode  because  well  Gonna Catch  em All   I find this approach useful because it allows PS Custom Objects  normal  NET objects  PS HashTables  and  NET collections like Dictionary to be treated as  duck-typed equivalent   which I find is a fairly good fit for PowerShell   Of course  this does not meet the strict definition of  has a property    which this question may be explicitly limited to  If accepting the larger definition of  property  assumed here  the method can be trivially modified to return a boolean   Function Get-PropOrNull       param  thing   string  prop      Try            thing  prop       Catch             Examples   Get-PropOrNull  Get-Date   Date                        gt  Monday  February 05  2018 12 00 00 AM Get-PropOrNull  Get-Date   flub                        gt   null Get-PropOrNull    x  HashTable     x                   gt   HashTable  Get-PropOrNull   PSCustomObject   x  Custom     x      gt   Custom   oldDict   New-Object  System Collections HashTable   oldDict  x      OldDict  Get-PropOrNull  d  x                                   gt   OldDict    And  this behavior might not  always  be desired   ie  it s not possible to distinguish between x Count and x  Count

User · Answer

You can use Get-Member  if Get-Member -inputobject  var -name  Property  -Membertype Properties    Property exists

User · Answer

You could check with     Member PropertyNames -contains  Name   this will check  for the Named property

User · Answer

Like this     bool   myObject PSobject Properties name -match  myPropertyNameToTest

User · Answer

If you are using StrictMode and the psobject might be empty  it will give you an error   For all purposes this will do        if    json PSobject Properties   Foreach     Name   -contains  variable

User · Answer

Real similar to a javascript check   foreach  member in  members        if  member PropertyName                Write  member PropertyName           else               Write  Nope

User · Answer

For identifying which of the objects in an array have a property   HasProperty    ArrayOfObjects   Where-Object     MyProperty

User · Answer

I just started using PowerShell with PowerShell Core 6 0  beta  and following simply works   if   members NoteProperty         NoteProperty exist     or  if  -not  members NoteProperty         NoteProperty does not exist

User · Answer

This is succinct and readable    MyProperty  -in  MyObject PSobject Properties Name   We can put it in a function   function HasProperty  object   propertyName         propertyName -in  object PSobject Properties Name

User · Answer

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

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

Examples related to powershell

Examples related to powershell-3.0