Suppose I have an array of hashes in Powershell v3:
> $hashes = 1..5 | foreach { @{Name="Item $_"; Value=$_}}
I can convert a single hash into a PSCustomObject
like this:
> $co = [PSCustomObject] $hashes[0]
> $co | ft -AutoSize
Value Name
----- ----
1 Item 1
> $co.GetType()
IsPublic IsSerial Name BaseType
-------- -------- ---- --------
True False PSCustomObject System.Object
So far, so good. The problem occurs when I try to convert the entire hash array into PSCustomObjects
in a pipeline:
> ($hashes | foreach { [PSCustomObject] $_})[0].getType()
IsPublic IsSerial Name BaseType
-------- -------- ---- --------
True True Hashtable System.Object
As you see, I'm getting an array of Hashtable
objects, not PSCustomObjects
. Why do I get different behavior, and how can I accomplish what I want?
Thanks.
Instead of casting, try calling New-Object
directly:
# > ($hashes | foreach { New-Object -TypeName PSCustomObject -Property $_})[0].getType()
IsPublic IsSerial Name BaseType
-------- -------- ---- --------
True False PSCustomObject System.Object
Also, oddly, this seems to work:
# > (0..4 | foreach { ([PSCustomObject]$hashes[$_])})[0].GetType()
IsPublic IsSerial Name BaseType
-------- -------- ---- --------
True False PSCustomObject System.Object
Why? I have no idea, it seems to have trouble performing the cast using a pipelined hashtable entry.
I have yet to figure out the exact cause (Everyone is still learning something) but your issue is related to the $_
pipe element somehow. I can make your code work if I force a cast of the $_
$hashes = 1..5 | foreach { @{Name="Item $_"; Value=$_}}
$hashes | %{([pscustomobject][hashtable]$_)}
Output
Value Name
----- ----
1 Item 1
2 Item 2
3 Item 3
4 Item 4
5 Item 5
Something curious
I didn't like Name
and Value
, while I was testing (That is what a literal hash table had for headers and I found it confusing while I was testing), so I changed the later to Data
and then the output differs. I only post it as it is curious. It is hard to show the results in the post.
Name Data
---- ----
Item 1 1
Item 2 2
Item 3 3
Item 4 4
Item 5 5
This seems to work:
$hashes = 1..5 | foreach { @{Name="Item $_"; Value=$_}}
foreach ($hash in $hashes)
{([PSCustomObject]$hash).gettype()}
It seems that value of pipeline variable $_
get wrapped into PSObject
and that break cast to PSCustomObject
.
> $hashes=@{Value=1},[PSObject]@{Value=2}
> $hashes[0].GetType().FullName
System.Collections.Hashtable
> $hashes[1].GetType().FullName
System.Collections.Hashtable
# It seems that both $hashes elements are Hashtable,
> [Type]::GetTypeArray($hashes).FullName
System.Collections.Hashtable
System.Management.Automation.PSObject
# But, as you can see, second one is not.
> ([PSCustomObject]$hashes[0]).GetType().FullName
System.Management.Automation.PSCustomObject
> ([PSCustomObject]$hashes[1]).GetType().FullName
System.Collections.Hashtable
# And that difference break cast to PSCustomObject.
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