How can I add child objects to a PsObject?

Question

Is this the correct way to have a PsObject as a Property of a parent PsObject?

This seems somewhat cumbersome to be the correct way and I can't dot source (see pictures at the bottom) the child PsObject's properties either.

$function1.Params | fl

InformationAction: @{InformationAction=IA1; Name=InformationAction; ParameterType=System.String; ParameterSets={[__AllParameterSets, System.Management.Automation.ParameterSetMetadata]}; IsDynamic=False; Aliases=ia; Attributes=; SwitchParameter=False}

WarningAction: @{WarningAction=IA1; Name=WarningAction; ParameterType=System.String; ParameterSets={[__AllParameterSets, System.Management.Automation.ParameterSetMetadata]}; IsDynamic=False; Aliases=ia; Attributes=; SwitchParameter=False}

ErrorAction: @{ErrorAction=IA1; Name=ErrorAction; ParameterType=System.String; ParameterSets={[__AllParameterSets, System.Management.Automation.ParameterSetMetadata]}; IsDynamic=False; Aliases=ia; Attributes=; SwitchParameter=False}

InformationVariable: @{InformationVariable=IA1; Name=InformationVariable; ParameterType=System.String; ParameterSets={[__AllParameterSets, System.Management.Automation.ParameterSetMetadata]}; IsDynamic=False; Aliases=ia; Attributes=; SwitchParameter=False}

WarningVariable: @{WarningVariable=IA1; Name=WarningVariable; ParameterType=System.String; ParameterSets={[__AllParameterSets, System.Management.Automation.ParameterSetMetadata]}; IsDynamic=False; Aliases=ia; Attributes=; SwitchParameter=False}

ErrorVariable: @{ErrorVariable=IA1; Name=ErrorVariable; ParameterType=System.String; ParameterSets={[__AllParameterSets, System.Management.Automation.ParameterSetMetadata]}; IsDynamic=False; Aliases=ia; Attributes=; SwitchParameter=False}

Here is a code snippet to duplicate what I am doing.

#Region Step 1 (create object)

    $function1 = New-Object PsObject;
    $function1 | Add-Member -NotePropertyName "Name" -NotePropertyValue "Test1";
    $function1 | Add-Member -NotePropertyName "Params" -NotePropertyValue $null;

    $param1 = New-Object PsObject;
    $param1 | Add-Member -NotePropertyName "InformationAction" -NotePropertyValue "IA1";
    $param1 | Add-Member -NotePropertyName "Name" -NotePropertyValue "InformationAction";
    $param1 | Add-Member -NotePropertyName "ParameterType" -NotePropertyValue "System.String";
    $param1 | Add-Member -NotePropertyName "ParameterSets" -NotePropertyValue "{[__AllParameterSets, System.Management.Automation.ParameterSetMetadata]}";
    $param1 | Add-Member -NotePropertyName "IsDynamic" -NotePropertyValue "False";
    $param1 | Add-Member -NotePropertyName "Aliases" -NotePropertyValue "ia";
    $param1 | Add-Member -NotePropertyName "Attributes" -NotePropertyValue $null;
    $param1 | Add-Member -NotePropertyName "SwitchParameter" -NotePropertyValue "False";

    $param2 = New-Object PsObject;
    $param2 | Add-Member -NotePropertyName "WarningAction" -NotePropertyValue "IA1";
    $param2 | Add-Member -NotePropertyName "Name" -NotePropertyValue "WarningAction";
    $param2 | Add-Member -NotePropertyName "ParameterType" -NotePropertyValue "System.String";
    $param2 | Add-Member -NotePropertyName "ParameterSets" -NotePropertyValue "{[__AllParameterSets, System.Management.Automation.ParameterSetMetadata]}";
    $param2 | Add-Member -NotePropertyName "IsDynamic" -NotePropertyValue "False";
    $param2 | Add-Member -NotePropertyName "Aliases" -NotePropertyValue "ia";
    $param2 | Add-Member -NotePropertyName "Attributes" -NotePropertyValue $null;
    $param2 | Add-Member -NotePropertyName "SwitchParameter" -NotePropertyValue "False";

    $param3 = New-Object PsObject;
    $param3 | Add-Member -NotePropertyName "ErrorAction" -NotePropertyValue "IA1";
    $param3 | Add-Member -NotePropertyName "Name" -NotePropertyValue "ErrorAction";
    $param3 | Add-Member -NotePropertyName "ParameterType" -NotePropertyValue "System.String";
    $param3 | Add-Member -NotePropertyName "ParameterSets" -NotePropertyValue "{[__AllParameterSets, System.Management.Automation.ParameterSetMetadata]}";
    $param3 | Add-Member -NotePropertyName "IsDynamic" -NotePropertyValue "False";
    $param3 | Add-Member -NotePropertyName "Aliases" -NotePropertyValue "ia";
    $param3 | Add-Member -NotePropertyName "Attributes" -NotePropertyValue $null;
    $param3 | Add-Member -NotePropertyName "SwitchParameter" -NotePropertyValue "False";

    $psObjectTemp = New-Object PsObject;
    $psObjectTemp | Add-Member -NotePropertyName $param1.Name -NotePropertyValue $param1;
    $psObjectTemp | Add-Member -NotePropertyName $param2.Name -NotePropertyValue $param2;
    $psObjectTemp | Add-Member -NotePropertyName $param3.Name -NotePropertyValue $param3;

    $function1.Params = $psObjectTemp

#EndRegion / Step 1 (create object)


#Region Step 2 (update object)

    $param4 = New-Object PsObject;
    $param4 | Add-Member -NotePropertyName "InformationVariable" -NotePropertyValue "IA1";
    $param4 | Add-Member -NotePropertyName "Name" -NotePropertyValue "InformationVariable";
    $param4 | Add-Member -NotePropertyName "ParameterType" -NotePropertyValue "System.String";
    $param4 | Add-Member -NotePropertyName "ParameterSets" -NotePropertyValue "{[__AllParameterSets, System.Management.Automation.ParameterSetMetadata]}";
    $param4 | Add-Member -NotePropertyName "IsDynamic" -NotePropertyValue "False";
    $param4 | Add-Member -NotePropertyName "Aliases" -NotePropertyValue "ia";
    $param4 | Add-Member -NotePropertyName "Attributes" -NotePropertyValue $null;
    $param4 | Add-Member -NotePropertyName "SwitchParameter" -NotePropertyValue "False";

    $param5 = New-Object PsObject;
    $param5 | Add-Member -NotePropertyName "WarningVariable" -NotePropertyValue "IA1";
    $param5 | Add-Member -NotePropertyName "Name" -NotePropertyValue "WarningVariable";
    $param5 | Add-Member -NotePropertyName "ParameterType" -NotePropertyValue "System.String";
    $param5 | Add-Member -NotePropertyName "ParameterSets" -NotePropertyValue "{[__AllParameterSets, System.Management.Automation.ParameterSetMetadata]}";
    $param5 | Add-Member -NotePropertyName "IsDynamic" -NotePropertyValue "False";
    $param5 | Add-Member -NotePropertyName "Aliases" -NotePropertyValue "ia";
    $param5 | Add-Member -NotePropertyName "Attributes" -NotePropertyValue $null;
    $param5 | Add-Member -NotePropertyName "SwitchParameter" -NotePropertyValue "False";

    $param6 = New-Object PsObject;
    $param6 | Add-Member -NotePropertyName "ErrorVariable" -NotePropertyValue "IA1";
    $param6 | Add-Member -NotePropertyName "Name" -NotePropertyValue "ErrorVariable";
    $param6 | Add-Member -NotePropertyName "ParameterType" -NotePropertyValue "System.String";
    $param6 | Add-Member -NotePropertyName "ParameterSets" -NotePropertyValue "{[__AllParameterSets, System.Management.Automation.ParameterSetMetadata]}";
    $param6 | Add-Member -NotePropertyName "IsDynamic" -NotePropertyValue "False";
    $param6 | Add-Member -NotePropertyName "Aliases" -NotePropertyValue "ia";
    $param6 | Add-Member -NotePropertyName "Attributes" -NotePropertyValue $null;
    $param6 | Add-Member -NotePropertyName "SwitchParameter" -NotePropertyValue "False";

    $psObjectTemp = New-Object PsObject;
    $psObjectTemp = $function1.Params;
    $psObjectTemp | Add-Member -NotePropertyName $param4.Name -NotePropertyValue $param4;
    $psObjectTemp | Add-Member -NotePropertyName $param5.Name -NotePropertyValue $param5;
    $psObjectTemp | Add-Member -NotePropertyName $param6.Name -NotePropertyValue $param6;
    
    $function1.Params = $psObjectTemp;

#EndRegion / Step 2 (update object)

After using the accepted answer, I am happy to see this

Answer 1

Another easy method using 'Select-Object'

The Implementation is faster and cleaner IMO.

$Row = "" | Select Col1,Col2,Col3,Col4
$Row2 = "" | Select Col5,Col6,Col7,Col8
$Row2.Col6 = "Test"

$Row.Col1 = "Data1"
$Row.Col2 = 50
$Row.Col3 = $Row2
$Row.Col4 = $Row2.Col6

Col1  Col2 Col3                              Col4
----  ---- ----                              ----
Data1   50 @{Col5=; Col6=Test; Col7=; Col8=} Test

If later, you want to add columns(properties) you can do:

$Row = $Row | Select *,Col10

Answer 2

You can greatly simplify the code using [PSCustomObject] literals and Add-Member -NotePropertyMembers to add multiple properties stored in a hashtable to an existing object. Also the temporary variable $psObjectTemp isn't really necessary.

#Region Step 1 (create object)

    $function1 = [PSCustomObject]@{
        Name = "Test1"
        Params = [PSCustomObject]@{
            InformationAction = [PSCustomObject]@{
                InformationAction = "IA1"
                Name = "InformationAction"
                ParameterType = "System.String"
                ParameterSets = "{[__AllParameterSets, System.Management.Automation.ParameterSetMetadata]}"
                IsDynamic = "False"
                Aliases = "ia"
                Attributes = $null
                SwitchParameter = "False"           
            }
            WarningAction = [PSCustomObject]@{
                <# TODO #>
            }
            ErrorAction = [PSCustomObject]@{
                <# TODO #>
            }
        }
    }


#EndRegion / Step 1 (create object)


#Region Step 2 (update object)

    $function1.Params | Add-Member -NotePropertyMembers @{
        InformationVariable = [PSCustomObject]@{
            InformationVariable = "IA1"
            Name = "InformationVariable"
            ParameterType = "System.String"
            ParameterSets = "{[__AllParameterSets, System.Management.Automation.ParameterSetMetadata]}"
            IsDynamic = "False"
            Aliases = "ia"
            Attributes = $null
            SwitchParameter = "False"            
        }
        WarningVariable = [PSCustomObject]@{
            <# TODO #>            
        }
        ErrorVariable = [PSCustomObject]@{
            <# TODO #>
        }
    }

#EndRegion / Step 2 (update object)