Pipeline works differently

Question

I'm a bit stuck. Why this pipeline returns nothing

Get-Content -Path C:\file.json | ConvertFrom-Json | Where-Object -Property FullName -Like "*somefilter*"

But when I split in into two pipelines it acually returns what I want - content of the json file (which is an array of objects) filtered by FullName

$t = Get-Content -Path C:\file.json | ConvertFrom-Json
$t | Where-Object -Property FullName -Like "*somefilter*"

Looks similar to [ConvertFrom-Json pipeline mystery](https://stackoverflow.com/questions/42842781). Could you post a JSON file example? — beatcracker, Nov 29 '21 at 09:20
`Get-Content -Path C:\file.json |ConvertFrom-Json |Write-Output |Where-Object ...`, see: [`#3424` ConvertFrom-Json sends objects converted from a JSON array as an *array* through the pipeline.](https://github.com/PowerShell/PowerShell/issues/3424) — iRon, Nov 29 '21 at 09:35
Yes. Thanks. It is definitely a duplicate. Just didn't figured out how to google it. — Mak Sim, Nov 29 '21 at 10:01

iRon · Accepted Answer · 2021-11-29T11:42:25.573

$Json = @'
[
  {
    "FullName": "a"
  },
  {
    "FullName": "b"
  },
  {
    "FullName": "c"
  }
]
'@

Issue

$Json |ConvertFrom-Json |Where-Object -Property FullName -Like 'a'

Returns nothing because in the older version of ConvertFrom-Json sends an array (as a single item) through the pipeline rather separate items:

($Json |ConvertFrom-Json).Count # returns 1 (in older versions of PowerShell)

As a workaround, you might simply unroll the pipeline items using Write-Output:

$Json |ConvertFrom-Json |Write-Output |Where-Object -Property FullName -Like 'a'

FullName
--------
a

The issue is resolved in newer PowerShell (core 7.x) versions.

1 Answers1