Create dynamicJsonClassAttributes-iter3.ps1

Pwsh/Modules/Text.Json/sketch/dynamicJsonClassAttributes-iter3.ps1

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+#Requires -Version 7
+using namespace System.Collections.Generic
+using namespace System.Text
+using namespace System.Text.Json
+using namespace System.Text.Json.Serialization
+using namespace System.Linq
+
+$assembly = Add-type -AssemblyName System.Text.Json -PassThru -ea 'stop'
+
+# This isn't an example of what you should do, it's testing what you can do
+
+function AutoJson {
+    <#
+    .SYNOPSIS
+        Try one of the automatic methods
+    .notes
+        [System.Text.Json.JsonSerializer] has a ton of overloads
+    .LINK
+        https://docs.microsoft.com/en-us/dotnet/api/system.text.json.jsonserializer?view=net-8.0#methods
+    #>
+    [CmdletBinding()]
+    param(
+        [Parameter(ValueFromPipeline)]
+        [Alias('InObj', 'In')]
+        [object] $Object,
+
+        # Without a type, it falls back to GetType()
+        [Alias('Tinfo', 'T')]
+        [type] $TypeInfo
+    )
+    process {
+        if(-not $TypeInfo ) { $TypeInfo = $Object.GetType() }
+        [Text.Json.JsonSerializer]::Serialize( <# value: #> $Object, <# tinfo #> $TypeInfo )
+
+        'AutoJson: TryConvert type: {0}' -f $TypeInfo | Write-verbose
+    }
+}
+
+$error.clear()
+$PSDefaultParameterValues['AutoJson:Ea'] = 'break'
+$PSDefaultParameterValues['AutoJson:Ea'] = 'continue'
+
+class SomePS {
+    [string] $ProcessName
+    [int] $Id
+
+    # [example kind 2]: Serialize property if it's not null, but ignore it if it's null
+    [JsonIgnoreAttribute( Condition = [JsonIgnoreCondition]::WhenWritingNull) ]
+    [string] $MainWindowTitle # next: test if ignore condition works on empty strings
+
+    # [example kind 1]: Property on instances to include, but, never serialize it
+    [Serialization.JsonIgnoreAttribute()]
+    [Diagnostics.ProcessModuleCollection] $Modules
+
+    SomePS ( [object]$Other ) {
+        $WantedProps = [Linq.Enumerable]::Intersect( # because linq is fun
+            [string[]]  $This.PSObject.Properties.Name,
+            [string[]] $Other.PSObject.Properties.Name )
+
+        foreach($PropName in $WantedProps) {
+            $This.$PropName = $Other.$PropName
+        }
+        # hard coded version:
+        # $This.ProcessName     = $Other.ProcessName
+        # $This.Id              = $Other.Id
+        # $this.MainWindowTitle = $Other.MainWindowTitle
+        # $This.Modules         = $Other.Module
+    }
+}
+$hasModules = get-process | ? Modules | select -First 1
+$hasTitle   = ( ps ) | ? MainWindowTitle | select -first 1
+$noTitle    = ( ps ) | ? -not MainWindowTitle | select -first 1
+
+# [a] works
+$hasModules -as [SomePS[]]
+<#  Out:
+    ProcessName             Id Modules
+    -----------             -- -------
+    ApplicationFrameHost 19636 {System.Diagnostics.ProcessModule (ApplicationFrameHost.exe), System.Diagnost ....
+#>
+
+$hasModules -as [SomePS[]] | %{ AutoJson -InObj $_ -TypeInfo ([SomePS]) }
+<#  Out:
+    {"ProcessName":"ApplicationFrameHost","Id":19636}
+#>
+
+# cool, typedata is constrained to derived types
+{
+    $hasModules -as [SomePS[]] | %{ AutoJson -InObj $_ -TypeInfo ([System.Diagnostics.Process]) }
+} | Should -Throw -because 'Typedef used did not derive from type'
+<#  Out:
+    Exception calling "Serialize" with "2" argument(s): "The specified
+        type [System.Diagnostics.Process] must derive from the specific value's type [SomePS]."
+#>
+
+# [b] not quite working
+h1 '[b]'
+$hasTitle -as [SomePs[]] | %{ AutoJson -InObj $_ }
+
+
+$hasModules, $hasTitle, $noTitle -as [SomePs[]]
+    | AutoJson
+
+<# Outputs:
+    {"ProcessName":"ApplicationFrameHost","Id":19636,"MainWindowTitle":"Snip \u0026 Sketch"}
+    {"ProcessName":"AggregatorHost","Id":9268,"MainWindowTitle":""}
+#>