How to display all properties with Format-Table cmdlet - powershell

Question

I have few [pscustomobject] objects that can have not all properties.
For example:
PS> $1 = [pscustomobject]#{ A='a1'; B='b1' }
PS> $2 = [pscustomobject]#{ A='a2'; C='c2' }
And I try to display all properties with Format-Table like this:
PS> $1,$2 | Format-Table
A B
- -
a1 b1
a2
PS> $2,$1 | Format-Table
A C
- -
a2 c2
a1
But every time it displays only properties from first object in collection.
I want to display all properties like if I set -Property argument explicitly.
PS> $1,$2 | Format-Table -Property A,B,C
A B C
- - -
a1 b1
a2 c2
Setting -Property argument is good if:
All set of properties is known in advance
Collection is small and I can get all properties with Get-Member -MemberType Properties
But I have a huge collection (above 10000 objects) with unknown properties so I need help with it.
REMARK: Format-Table will be used only for small slices (10-100 elements).

Answer 1

For that, you can use below function to merge all properties into the first object:
function Complete-ObjectHeaders {
# function to add properties to the first item in a collection of PSObjects
# when this object is missing properties from items further down the array.
# you may need this if you have such a collection and want to export it
# to Csv, since Export-Csv (and also Format-Table) only looks at the FIRST
# item to create the csv column headers.
[CmdletBinding()]
param (
[Parameter(Mandatory = $true, Position = 0)]
[PSObject[]]$Collection,
[int]$MaxItemsToTest = -1, # < 0 --> test all items in the collection
[switch]$SortHeaders
)
# Try and find all headers by looping over the items in the collection.
# The headers will be captured in the order in which they are found.
if ($MaxItemsToTest -gt 0) {
$MaxItemsToTest = [math]::Min($MaxItemsToTest, $Collection.Count)
$headers = for($i = 0; $i -lt $MaxItemsToTest; $i++) {
($Collection[$i].PSObject.Properties).Name
}
$headers = $headers | Select-Object -Unique
}
else {
$headers = $Collection | ForEach-Object {($_.PSObject.Properties).Name} | Select-Object -Unique
}
if ($SortHeaders) { $headers = $headers | Sort-Object }
# update the first object in the collection to contain all headers
$Collection[0] = $Collection[0] | Select-Object $headers
,$Collection
}
Use like this:
$1 = [pscustomobject]#{ A='a1'; B='b1' }
$2 = [pscustomobject]#{ A='a2'; C='c2' }
# just output to console
Complete-ObjectHeaders -Collection $1,$2 | Format-Table -AutoSize
# or capture the merged array of objects in a new variable you can save as CSV file for instance
$merged = Complete-ObjectHeaders -Collection $1,$2
$merged | Export-Csv -Path 'D:\Test\Merged.csv' -NoTypeInformation
Output:
A B C
- - -
a1 b1
a2 c2

Answer 2

Thanks #theo for the answer.
I used it to write my own version of a function that supports pipelining.
function Expand-Properties {
[Cmdletbinding()]
param(
[Parameter(ValueFromPipeline)]
$InputObject,
[Parameter()]
[Alias('All')]
[switch]
$ExpandAll,
[Parameter()]
[switch]
$SortHeaders
)
begin {
$collection = [System.Collections.ArrayList]::new()
$properties = [System.Collections.ArrayList]::new()
}
process {
[void]$collection.Add($InputObject)
$properties.AddRange((($InputObject.PSObject.Properties).Name))
}
end {
if ($SortHeaders) {
$properties = $properties | Sort-Object -Unique
} else {
$properties = $properties | Select-Object -Unique
}
if ($ExpandAll) {
for ($i = 0; $i -lt $collection.Count; ++$i) {
$collection[$i] = $collection[$i] | Select-Object -Property $properties
}
} else {
$collection[0] = $collection[0] | Select-Object -Property $properties
}
$collection
}
}
EXAMPLE:
PS> $1 = [pscustomobject]#{ A='a1'; B='b1' }
PS> $2 = [pscustomobject]#{ A='a2'; C='c2' }
PS> $1, $2 | Expand-Properties
A B C
- - -
a1 b1
a2 c2