Styjun

Adding strings in lists together

Get LaTeX form from step by step solution

Can an old DSLR be upgraded to match modern smartphone image quality

Rotated Position of Integers

Is it possible to kill all life on Earth?

Why is there a need to modify system call tables in linux?

If I create magical darkness with the Silent Image spell, can I see through it if I have the Devil's Sight warlock invocation?

Infinitely many hats

Term for checking piece whose opponent daren't capture it

Team member doesn't give me the minimum time to complete a talk

Can a helicopter mask itself from Radar?

Is a hash a zero-knowledge proof?

Are UK pensions taxed twice?

Draw a checker pattern with a black X in the center

How can I grammatically understand "Wir über uns"?

Could I be denied entry into Ireland due to medical and police situations during a previous UK visit?

What is game ban VS VAC ban in steam?

chmod would set file permission to 000 no matter what permission i try to set

Different PCB color ( is it different material? )

Humans meet a distant alien species. How do they standardize? - Units of Measure

How do I subvert the tropes of a train heist?

Hiker's Cabin Mystery | Pt. IX

Did airlines fly their aircraft slower in response to oil prices in the 1970s?

Expenditure in Poland - Forex doesn't have Zloty

Check for $null in if statement

Powershell: Get-Process Returns “Invalid” VM SizeHow to dynamically define a class in C# PowerShell CmdletRename computer and join to domain in one step with PowerShellHow do I get total physical memory size using PowerShell without WMI?Powershell: Dynamically Convert Get-WMIObject to PSObjectPowershell - RPC, OBJ Null and -Replace ERRORS in MySQL insert querywin32_physicalMemory.Capacity returns null in powershell.count in multiple powershell versionsGet total amount of memory on NUMA systems in PowershellFiltering Get-WmiObject Class Property Output to include only value

.everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty height:90px;width:728px;box-sizing:border-box;

0

The following script works well on newer powershell versions but I also need a version for powershell 2.0.

The problem seems to be that I can't use if ($class.$property -eq $null) here, but something like if (($class | select -expand $property) -eq $null) won't work too.

So how can I check if $class.$property is null in powershell 2.0?

script:
(there are more values I need later, but this shows the problem because SKU is null in my case)

function Get-Value-From-Class($class, $property) 
 if ($class.$property -eq $null) 
 # property is null
 $arr = @()

 for ($i=1; $i -le $class.count; $i++) 
 $arr += $null
 

 return $arr
 else select -expand $property
 



$memory = Get-WmiObject -class Win32_PhysicalMemory
$result = @memory = @

$result.memory.capacity = Get-Value-From-Class -class $memory -property Capacity # this is not null
$result.memory.sku = Get-Value-From-Class -class $memory -property SKU # this is null here

$result | ConvertTo-Json # I know this won't work too but I have a polyfill for this

output on powershell 5 (and like I would need it in 2.0 also):

 "memory": 
 "sku": [
 null,
 null
 ],
 "capacity": [
 8589934592,
 8589934592
 ]
 

---

As Theo suggested:

[... code for ConvertTo-STJson ...]

function Get-Value-From-Class($class, $property) 
 if (!($class.$property)) 
 return "top"
 else 
 return "bottom"
 



$memory = Get-WmiObject -class Win32_PhysicalMemory

$result = @memory = @;

$result.memory.capacity = Get-Value-From-Class -class $memory -property Capacity
$result.memory.sku = Get-Value-From-Class -class $memory -property SKU

ConvertTo-STJson -InputObject $result | Out-File .json_output.json -Encoding utf8

This gives different results für different powershell versions:

result with 2.0

 "memory":
 
 "sku": "top",
 "capacity": "top"
 

result with 5.1

 "memory":
 
 "sku": "bottom",
 "capacity": "bottom"
 

powershell powershell-v2.0

share|improve this question

edited Mar 24 at 13:26

Michon

asked Mar 24 at 9:52

MichonMichon

254

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  You should test with if (!($class.$property)) instead of testing for equality with $null. Then, as you already know, in PowerShell version 2, there is no ConvertTo-Json. If you do need that, I suggest you look for modules on the internet like perhaps ConvertTo-STJson
  
  – Theo
  Mar 24 at 11:18
  
  

  
  
  
  


• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  Also, if you specifically want to check for $null, it is best to put the $null on the lefthand side of the equasion. See Null comparison demystified
  
  – Theo
  Mar 24 at 11:23
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Thank you @Theo but this behaves different on different versions of powershell. I edited the question to show you what I mean. Any idea why this happens?
  
  – Michon
  Mar 24 at 13:28
  

  
  
  
  


• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  When testing, using this syntax if (!($class[$property])) seems to return the same results in PS 5.1 and PS 2.0. However, the returned value for Get-WmiObject -Class Win32_PhysicalMemory is an array while your function Get-Value-From-Class does not deal with arrays. In this case send it the index of one item in the array (Get-Value-From-Class -class $memory[0]) or adapt your function to handle arrays of objects. As an aside, to get the total physical memory in GB, you can use (Get-WmiObject Win32_PhysicalMemory | Measure-Object Capacity -sum).sum / 1GB
  
  – Theo
  Mar 24 at 15:12
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @Theo You're absolutely right, thank you.
  
  – Michon
  Mar 26 at 10:28
  

  
  
  
  

add a comment | 

0

The following script works well on newer powershell versions but I also need a version for powershell 2.0.

The problem seems to be that I can't use if ($class.$property -eq $null) here, but something like if (($class | select -expand $property) -eq $null) won't work too.

So how can I check if $class.$property is null in powershell 2.0?

script:
(there are more values I need later, but this shows the problem because SKU is null in my case)

function Get-Value-From-Class($class, $property) 
 if ($class.$property -eq $null) 
 # property is null
 $arr = @()

 for ($i=1; $i -le $class.count; $i++) 
 $arr += $null
 

 return $arr
 else select -expand $property
 



$memory = Get-WmiObject -class Win32_PhysicalMemory
$result = @memory = @

$result.memory.capacity = Get-Value-From-Class -class $memory -property Capacity # this is not null
$result.memory.sku = Get-Value-From-Class -class $memory -property SKU # this is null here

$result | ConvertTo-Json # I know this won't work too but I have a polyfill for this

output on powershell 5 (and like I would need it in 2.0 also):

 "memory": 
 "sku": [
 null,
 null
 ],
 "capacity": [
 8589934592,
 8589934592
 ]
 

---

As Theo suggested:

[... code for ConvertTo-STJson ...]

function Get-Value-From-Class($class, $property) 
 if (!($class.$property)) 
 return "top"
 else 
 return "bottom"
 



$memory = Get-WmiObject -class Win32_PhysicalMemory

$result = @memory = @;

$result.memory.capacity = Get-Value-From-Class -class $memory -property Capacity
$result.memory.sku = Get-Value-From-Class -class $memory -property SKU

ConvertTo-STJson -InputObject $result | Out-File .json_output.json -Encoding utf8

This gives different results für different powershell versions:

result with 2.0

 "memory":
 
 "sku": "top",
 "capacity": "top"
 

result with 5.1

 "memory":
 
 "sku": "bottom",
 "capacity": "bottom"
 

powershell powershell-v2.0

share|improve this question

edited Mar 24 at 13:26

Michon

asked Mar 24 at 9:52

MichonMichon

254

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  You should test with if (!($class.$property)) instead of testing for equality with $null. Then, as you already know, in PowerShell version 2, there is no ConvertTo-Json. If you do need that, I suggest you look for modules on the internet like perhaps ConvertTo-STJson
  
  – Theo
  Mar 24 at 11:18
  
  

  
  
  
  


• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  Also, if you specifically want to check for $null, it is best to put the $null on the lefthand side of the equasion. See Null comparison demystified
  
  – Theo
  Mar 24 at 11:23
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Thank you @Theo but this behaves different on different versions of powershell. I edited the question to show you what I mean. Any idea why this happens?
  
  – Michon
  Mar 24 at 13:28
  

  
  
  
  


• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  When testing, using this syntax if (!($class[$property])) seems to return the same results in PS 5.1 and PS 2.0. However, the returned value for Get-WmiObject -Class Win32_PhysicalMemory is an array while your function Get-Value-From-Class does not deal with arrays. In this case send it the index of one item in the array (Get-Value-From-Class -class $memory[0]) or adapt your function to handle arrays of objects. As an aside, to get the total physical memory in GB, you can use (Get-WmiObject Win32_PhysicalMemory | Measure-Object Capacity -sum).sum / 1GB
  
  – Theo
  Mar 24 at 15:12
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @Theo You're absolutely right, thank you.
  
  – Michon
  Mar 26 at 10:28
  

  
  
  
  

add a comment | 

The following script works well on newer powershell versions but I also need a version for powershell 2.0.

The problem seems to be that I can't use if ($class.$property -eq $null) here, but something like if (($class | select -expand $property) -eq $null) won't work too.

So how can I check if $class.$property is null in powershell 2.0?

script:
(there are more values I need later, but this shows the problem because SKU is null in my case)

function Get-Value-From-Class($class, $property) 
 if ($class.$property -eq $null) 
 # property is null
 $arr = @()

 for ($i=1; $i -le $class.count; $i++) 
 $arr += $null
 

 return $arr
 else select -expand $property
 



$memory = Get-WmiObject -class Win32_PhysicalMemory
$result = @memory = @

$result.memory.capacity = Get-Value-From-Class -class $memory -property Capacity # this is not null
$result.memory.sku = Get-Value-From-Class -class $memory -property SKU # this is null here

$result | ConvertTo-Json # I know this won't work too but I have a polyfill for this

output on powershell 5 (and like I would need it in 2.0 also):

 "memory": 
 "sku": [
 null,
 null
 ],
 "capacity": [
 8589934592,
 8589934592
 ]
 

---

As Theo suggested:

[... code for ConvertTo-STJson ...]

function Get-Value-From-Class($class, $property) 
 if (!($class.$property)) 
 return "top"
 else 
 return "bottom"
 



$memory = Get-WmiObject -class Win32_PhysicalMemory

$result = @memory = @;

$result.memory.capacity = Get-Value-From-Class -class $memory -property Capacity
$result.memory.sku = Get-Value-From-Class -class $memory -property SKU

ConvertTo-STJson -InputObject $result | Out-File .json_output.json -Encoding utf8

This gives different results für different powershell versions:

result with 2.0

 "memory":
 
 "sku": "top",
 "capacity": "top"
 

result with 5.1

 "memory":
 
 "sku": "bottom",
 "capacity": "bottom"
 

powershell powershell-v2.0

share|improve this question

edited Mar 24 at 13:26

Michon

asked Mar 24 at 9:52

MichonMichon

254

function Get-Value-From-Class($class, $property) 
 if ($class.$property -eq $null) 
 # property is null
 $arr = @()

 for ($i=1; $i -le $class.count; $i++) 
 $arr += $null
 

 return $arr
 else select -expand $property
 



$memory = Get-WmiObject -class Win32_PhysicalMemory
$result = @memory = @

$result.memory.capacity = Get-Value-From-Class -class $memory -property Capacity # this is not null
$result.memory.sku = Get-Value-From-Class -class $memory -property SKU # this is null here

$result | ConvertTo-Json # I know this won't work too but I have a polyfill for this

 "memory": 
 "sku": [
 null,
 null
 ],
 "capacity": [
 8589934592,
 8589934592
 ]
 

[... code for ConvertTo-STJson ...]

function Get-Value-From-Class($class, $property) 
 if (!($class.$property)) 
 return "top"
 else 
 return "bottom"
 



$memory = Get-WmiObject -class Win32_PhysicalMemory

$result = @memory = @;

$result.memory.capacity = Get-Value-From-Class -class $memory -property Capacity
$result.memory.sku = Get-Value-From-Class -class $memory -property SKU

ConvertTo-STJson -InputObject $result | Out-File .json_output.json -Encoding utf8

 "memory":
 
 "sku": "top",
 "capacity": "top"
 

 "memory":
 
 "sku": "bottom",
 "capacity": "bottom"
 

share|improve this question

edited Mar 24 at 13:26

Michon

asked Mar 24 at 9:52

MichonMichon

254

share|improve this question

edited Mar 24 at 13:26

Michon

asked Mar 24 at 9:52

MichonMichon

254

asked Mar 24 at 9:52

MichonMichon

254

asked Mar 24 at 9:52

MichonMichon

254