Save hash table in PowerShell object notation (PSON)

After 5 years, the cmdlet I had pasted in the original answer has undergone so many updates that it has become completely outdated. Therefore I have replaced the code and the ReadMe with a link to the latest version.

Besides the support for more object types and better formatting, it now outputs an expression (ScriptBlock), which default display type is still a String and allows for direct invocation using the call operator &:

$Object = &($Object | ConverTo-Expression)

ConvertTo-Expression

The ConvertTo-Expression cmdlet can be download from PowerShell Gallery using the command:

Install-Script -Name ConvertTo-Expression

ReadMe

The full ReadMe (and source code) is available from GitHub:
https://github.com/iRon7/ConvertTo-Expression

Installation

After downloading (Install-Script -Name ConvertTo-Expression), the script can simply be invoked by dot sourcing:

. .\ConvertTo-Expression.ps1

You might also consider to convert the script to a PowerShell module by renaming it to a PowerShell module (.psm1) file and moving it to a one of the module folders defined in $env:PSModulePath. For more details see: How to Write a PowerShell Script Module.

Answer

Below are some possible options to serialize the specific example (assigned to $Craig) in the question:

ConvertTo-Expression $Craig@{    parameters =        @{            name = 'parameter 0'            default = 1            values =                1,                2,                3,                4        },        @{            name = 'parameter 1'            default = 'A'            values =                'A',                'B',                'C'        }    name = 'report 0'}

To limit the tree view expansion:
_{(Expand -0 will output a single line and Expand -1 will remove also the unnecessary spaces)}

ConvertTo-Expression $Craig -expand 3@{    parameters =        @{name = 'parameter 0'; default = 1; values = 1, 2, 3, 4},        @{name = 'parameter 1'; default = 'A'; values = 'A', 'B', 'C'}    name = 'report 0'}

Preserving the explicit types (strong typed):

ConvertTo-Expression $Craig -expand 3 -Strong[hashtable]@{    parameters = [array](        [hashtable]@{name = [string]'parameter 0'; default = [int]1; values = [array]([int]1, [int]2, [int]3, [int]4)},        [hashtable]@{name = [string]'parameter 1'; default = [string]'A'; values = [array]([string]'A', [string]'B', [string]'C')}    )    name = [string]'report 0'}

_{(Note: As per PowerShell design, HashTables are not in order, but if required you might use the [Ordered] type instead.)}

Try the *-CliXml cmdlets. To save the object:

@{             "name" = "report 0"             "parameters" = @(    @{"name" = "parameter 0"; "default" = 1; "values"=1,2,3,4},    @{"name" = "parameter 1"; "default" = 'A'; "values" = 'A','B','C'}    )            } | Export-Clixml -Path c:\hash.xml

To read it back:

Import-Clixml c:\hash.xml

One way would be to put the hashtable definition in a scriptblock:

$hashtable = {  @{                "name" = "report 0"                "parameters" = @(        @{"name" = "parameter 0"; "default" = 1; "values"=1,2,3,4},        @{"name" = "parameter 1"; "default" = 'A'; "values" = 'A','B','C'}        )                }}$hashtable.tostring()

@{
"name" = "report 0"
"parameters" = @( @{"name" = "parameter 0"; "default" = 1; "values"=1,2,3,4}, @{"name" = "parameter 1"; "default" = 'A'; "values" = 'A','B','C'} )
}

Within the script, you'd need to invoke the script block to instantiate the hashtable:

$hash = .$hashtable