Not all properties displayed

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I had the same experience once and created the following reusable ‘Union‘ function:

# 2021-08-25 Removed Union function

Usage:

$Obj1, $Obj2 | Union | Out-GridView -Title 'Showing all members'

It is also supposed to work with complex objects. Some standard cmdlets output multiple object types at once and if you view them (e.g. Out-GridView) or dump them in a file (e.g. Export-Csv) you might miss a lot of properties. Take as another example:

Get-WmiObject -Namespace root/hp/instrumentedBIOS -Class hp_biosSetting | Union | Export-Csv ".\HPBIOS.csv"

Added 2014-09-19:

Maybe this is already between the lines in the comments $Array | Select * | … will not resolve the issue but specifically selecting the properties $Array | Select Member1, Member2, Member3 | … does.
Besides, although in most cases the Union function will work, there are some exceptions to that as it will only align the first object with the rest.
Consider the following object:

$List = @(
    New-Object PSObject -Property @{Id = 2}
    New-Object PSObject -Property @{Id = 1}
    New-Object PSObject -Property @{Id = 3; Name = "Test"}
)

If you Union this object everything appears to be fine and if you e.g. ExportTo-CSV and work with the export .csv file from then on you will never have any issue.

$List | Union
Id Name
-- ----
 2
 1
 3 Test

Still there is a catch as only the first object is aligned. If you e.g. sort the result on Id (Sort Id) or take just the last 2 (Select -Last 2) entries, the Name is not listed because the second object doesn’t contain the Name property:

$List | Union | Sort Id
Id
--
 1
 2
 3

Therefor I have rewritten the Union-Object (Alias Union) function`):

Union-Object

# 2021-08-25 Removed Union-Object function

Syntax:

$Array | Union | Out-GridView -Title 'All members correctly displayed'

Update 2021-08-25

Based on az1d helpful feedback on an error caused by equal property names with different casing, I have created a new UnifyProperties function.
(I will no longer use the name UnionObject for his)

function UnifyProperties {
  $Names = [System.Collections.Generic.HashSet[string]]::new([StringComparer]::OrdinalIgnoreCase)
  $InputCollected = @($Input)
  $InputCollected.ForEach({ 
    foreach ($Name in $_.psobject.Properties.Name) { $Null = $Names.Add($Name) }
  })
  $inputCollected | Select-Object @($Names)
}

Usage:

[pscustomobject] @{ one = 1; two = 2; three = 3 },
[pscustomobject] @{ ONE = 10; THREE = 30; FOUR = 4 } |
    UnifyProperties

one two three FOUR
--- --- ----- ----
  1   2     3
 10        30 4

See also: #13906 Add -UnifyProperties parameter to Select-Object

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