jsonpowershellpowershell-4.0

How to exclude non-valued object properties when converting to JSON in Powershell


I have a piece of code that works but I want to know if there is a better way to do it. I could not find anything related so far. Here are the facts:

  • I have an object with n properties.
  • I want to convert this object to JSON using (ConvertTo-Json).
  • I don't want to include in the JSON those object properties that are not valued.

Building the object (not really important):

$object = New-Object PSObject
Add-Member -InputObject $object -MemberType NoteProperty -Name TableName -Value "MyTable"
Add-Member -InputObject $object -MemberType NoteProperty -Name Description -Value "Lorem ipsum dolor.."
Add-Member -InputObject $object -MemberType NoteProperty -Name AppArea -Value "UserMgmt"
Add-Member -InputObject $object -MemberType NoteProperty -Name InitialVersionCode -Value ""

The line that I need improvements (to filter out the non-valued properties and not include them in the JSON)

# So I want to 'keep' and deliver to the JSON only the properties that are valued (first 3).
$object | select -Property TableName, Description, AppArea, InitialVersion | ConvertTo-Json

What this line delivers:

Results:
{
    "TableName":  "MyTable",
    "Description":  "Lorem ipsum dolor..",
    "AppArea":  "UserMgmt",
    "InitialVersion":  null
}

What I want to obtain:
{
    "TableName":  "MyTable",
    "Description":  "Lorem ipsum dolor..",
    "AppArea":  "UserMgmt"
}

What I've tried and works, but I don't like it since I have much more properties to handle:

$JSON = New-Object PSObject

if ($object.TableName){
   Add-Member -InputObject $JSON -MemberType NoteProperty -Name TableName -Value $object.TableName
}

if ($object.Description){
   Add-Member -InputObject $JSON -MemberType NoteProperty -Name Description -Value $object.Description
}

if ($object.AppArea){
   Add-Member -InputObject $JSON -MemberType NoteProperty -Name AppArea -Value $object.AppArea
}

if ($object.InitialVersionCode){
   Add-Member -InputObject $JSON -MemberType NoteProperty -Name InitialVersionCode -Value $object.InitialVersionCode
}

$JSON | ConvertTo-Json

Solution

  • Something like this?

    $object = New-Object PSObject
    
    Add-Member -InputObject $object -MemberType NoteProperty -Name TableName -Value "MyTable"
    Add-Member -InputObject $object -MemberType NoteProperty -Name Description -Value "Lorem ipsum dolor.."
    Add-Member -InputObject $object -MemberType NoteProperty -Name AppArea -Value "UserMgmt"
    Add-Member -InputObject $object -MemberType NoteProperty -Name InitialVersionCode -Value ""
    
    # Iterate over objects
    $object | ForEach-Object {
        # Get array of names of object properties that can be cast to boolean TRUE
        # PSObject.Properties - https://msdn.microsoft.com/en-us/library/system.management.automation.psobject.properties.aspx
        $NonEmptyProperties = $_.psobject.Properties | Where-Object {$_.Value} | Select-Object -ExpandProperty Name
    
        # Convert object to JSON with only non-empty properties
        $_ | Select-Object -Property $NonEmptyProperties | ConvertTo-Json
    }
    

    Result:

    {
        "TableName":  "MyTable",
        "Description":  "Lorem ipsum dolor..",
        "AppArea":  "UserMgmt"
    }