Question 272897 in Json Question posted in
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How to avoid nulling array in JSON with PoweShell

I working with JSON file:

{
    "Job":  "abc",
    "Tasks":  [
                  {
                      "Task":  1
                  },
                  {
                      "Task":  2
                  }
              ]
}

and in some cases I have to remove all tasks and then my output JSON file looks like this:

{
    "Job":  "abc",
    "Tasks": null
}

PowerShell code which I’m using to remove tasks below:

$Job = Get-Content -Path '.Job.json'|ConvertFrom-Json
$Tasks = $Job.Tasks
$Tasks = $Tasks|Where-Object {$_.Task -ne 1}
$Tasks = $Tasks|Where-Object {$_.Task -ne 2}
$Job|ConvertTo-JSON -Depth 2|Out-File -Path '.Job.json'

This JSON file is used by other tools and this null field causing issues.
I have tried to use Array and ArrayList but as far as I found PowerShell doesn’t support indexOf() method so I don’t know which item has to be removed.

Tags:

2

Answers


  1. Chosen as BEST ANSWER
    0

    OK, I think I found solution - it's not super clean but it's working

        $Job = Get-Content -Path '.Job.json'|ConvertFrom-Json
    $Job.Tasks = $Job.Tasks|Where-Object {$_.Task -ne 1}
    $Job.Tasks = $Job.Tasks|Where-Object {$_.Task -ne 2}
    if(-not ($Job.Tasks)){
        $Job.Tasks = @()
    }
    else {
        $Job.Tasks = , $Job.Tasks
    }
    $Job|ConvertTo-Json -Depth 2|Out-File -FilePath '.Job.json'

  2. 0

    Use @(...), the array-subexpression operator, whose purpose is exactly to ensure that a pipeline’s collected output is unconditionally made an array – even if there is no or just one output object:

    $job = Get-Content -Raw .Job.json | ConvertFrom-Json

# Use @(...) to ensure the output becomes an array.
$job.Tasks = @($job.Tasks | Where-Object { $_.Task -notin 1, 2 })

$job | ConvertTo-Json -Depth 2 | Out-File .Job.json

    Note:

    • Using -Raw with Get-Content is more efficient: it reads the entire file into a single string.

    • A single Where-Object call is used, using a single logical operation based on -notin operator.

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