PowerShell helpers

custom-class-as-validator.ps1

# Custom validator for one element
class ValidateElementAttribute : System.Management.Automation.ValidateArgumentsAttribute
{
    [void]  Validate([object]$arguments, [System.Management.Automation.EngineIntrinsics]$engineIntrinsics)
    {

        # Validation happens here
        if ($arguments -ne "foo") {
            throw "you should have chosen foo"
        }
    }
}

# Custom validator for multiple elements
class ValidateElementsAttribute : System.Management.Automation.ValidateEnumeratedArgumentsAttribute
{
    [void]  ValidateElement([object]$arguments)
    {
        
        # Check each element here
        if ($arguments -notmatch "^f") {
            throw "nope... not f*. maybe try 'foo' or 'flute' or 'fsck'"
        }
               
    }
}

function Do-Something
{
    [cmdletbinding()]
    param(
        [ValidateElement()]
        $A,
        [ValidateElements()]
        $B
    )

    if ($A) {
        write-host $A
    }

    if ($B) {
        write-host $B
    }

}

# Throws an exception
Do-Something -A poo

# Does not throw exception
Do-Something -A foo

# Throws exception
Do-Something -B @("foo","food","pooo")

# Does not throw exception
Do-Something -B @("foo","food","flute")

get-eventlog-from-all-activedirectory-computers.ps1

# cast active directory names to computername
get-adcomputer -filter * | 
select-object -Property @{N='ComputerName'; E={$_.Name}} | 
% { get-eventlog -LogName system -EntryType error, warning -after $(get-date).AddDays(-2) -ComputerName $_.computername | 
sort source | 
select-object InstanceId, MachineName, source } | 
Export-Clixml (get-date -format filedate)-system.xml

# set active directory names to an array
$computers = $(get-adcomputer -filter *).Name
get-eventlog -LogName system -EntryType error, warning -after $(get-date).AddDays(-2) -ComputerName $computers | 
sort source | 
select-object InstanceId, MachineName, source

# invoke command
$computers = $(get-adcomputer -filter *).Name
invoke-command {get-eventlog -LogName system -EntryType error, warning -after $(get-date).AddDays(-2)} 
-ComputerName $computers | 
sort source | 
select-object InstanceId, MachineName, source

handling-nested-json.ps1

$json = '{
    "keystores": {
      "/usr/local/cert/foo/cert1.jks:signing1": {
        "days_remaining": 629,
        "issuer": "C=SE O=Inera AB CN=SITHS Type 3 CA v1 PP",
        "owner": "C=SE L=Vanersborg O=Vastra Gotalands Lans Landsting CN=footest.vgregion.se serialNumber=12345"
      },      
      "/usr/local/cert/foo/cert1.jks:signing2": {
        "days_remaining": 629,
        "issuer": "C=SE O=Inera AB CN=SITHS Type 3 CA v1 PP",
        "owner": "C=SE L=Vanersborg O=Vastra Gotalands Lans Landsting CN=footest.vgregion.se serialNumber=12345"
      },
      "/usr/local/cert/foo/cert1.jks:encryption1": {
        "days_remaining": 594,
        "issuer": "C=SE L=Stockholm O=Foo AB OU=Foo CN=Foo Bar Root",
        "owner": "serialNumber=12345 C=SE O=Foo AB OU=Foo CN=encryption"
      },
      "/usr/local/cert/foo.domain.org_siths_type3_ca_v1_pp_auth.p12:1": {
        "days_remaining": 531,
        "issuer": "C=SE O=Inera AB CN=SITHS Type 3 CA v1 PP",
        "owner": "C=SE L=Vanersborg O=Vastra Gotalands Lans Landsting CN=footest.vgregion.sjunet.org serialNumber=1234"
      },
      "/usr/local/cert/footest.domain.com_siths_type3_ca_v1_pp_auth.p12:1": {
        "days_remaining": 537,
        "issuer": "C=SE O=Inera AB CN=SITHS Type 3 CA v1 PP",
        "owner": "C=SE L=Vanersborg O=Vastra Gotalands Lans Landsting CN=footest.vgregion.se serialNumber=1234"
      }
    }
  }'

$o = $json | ConvertFrom-Json
foreach ($info in $o.keystores.PSObject.Properties) {
    [pscustomobject]@{
    "Name"=$info.Name;
    "Days_Remaining"=$info.Value.days_remaining;
    "Issuer"=$info.Value.issuer;
    "Owner"=$info.Value.owner
    }
}

invoke-command-on-remote-host.ps1

# get-wmi with computers from active directory 
invoke-command {gwmi -Class win32_logicaldisk} -ComputerName $(get-adcomputer -filter *).name

# same with get-ciminstance
invoke-command { Get-CimClass -ClassName win32_logicaldisk } -ComputerName $(Get-ADComputer -filter *).Name

# using cim sessions
$s = New-CimSession -ComputerName $(Get-ADComputer -filter *).name
Get-CimSession | gcim Win32_LogicalDisk

# using cim sessions one-liner
$s = New-CimSession -computername $(get-adcomputer -filter *).name; 
Get-CimSession | 
gcim Win32_LogicalDisk; 
Get-CimSession | Remove-CimSession

using-cim.ps1

# using cim sessions
$s = New-CimSession -ComputerName $(Get-ADComputer -filter *).name
Get-CimSession | gcim Win32_LogicalDisk

using-classes.ps1

enum category {
    suspense
    detective
    horror
    romance
    comedy
    biography
}

class Book {

    [string] $title
    [string] $author
    [datetime] $published
    [float] $rating
    [string] $owner
    [category] $category

    Book ($title, $author, $published, $owner, $category) {
        $this.title = $title
        $this.author = $author
        $this.published = $published
        $this.owner = $owner
        $this.category = $category
    }

    sell($owner) {
        $this.owner = $owner
    }

}

class GoodreadsBook {

    [string] $title
    [string] $owner
    [category] $category

    [book] getInformation ($title, $category, $owner, $goodreadsKey) {
        [string] $encodedTitle = [System.Web.HttpUtility]::UrlEncode($title)
        [string] $url = "https://www.goodreads.com/search.xml?key=${goodreadsKey}&q=${encodedTitle}"
        $request = Invoke-RestMethod $url

        [int]$year = $request.GoodreadsResponse.search.results.work[0].original_publication_year."#text"
        [string]$month = "{0:D2}" -f [int]$request.GoodreadsResponse.search.results.work[0].original_publication_month."#text"
        [string]$day = "{0:D2}" -f [int]$request.GoodreadsResponse.search.results.work[0].original_publication_day."#text"
        $author = $request.GoodreadsResponse.search.results.work[0].best_book.author.name
        $goodreadsTitle = $request.GoodreadsResponse.search.results.work[0].best_book.title
        #$rating = $request.GoodreadsResponse.search.results.work[0].average_rating
        
        #$this.publishedDate = [DateTime]::ParseExact("${year}-${month}-${day} 00:00:00,000", "yyyy-MM-dd HH:mm:ss,fff", [System.Globalization.CultureInfo]::InvariantCulture)
        $published = [DateTime]::ParseExact("${year}-${month}-${day}", "yyyy-MM-dd",[System.Globalization.CultureInfo]::InvariantCulture)
        return [Book]::new($goodreadsTitle, $author, $published, $owner, $category)
       
    }

}

function sellBook () {
    [cmdletbinding()]
    param (
        [book] $book,
        [string] $owner
    )

    begin {}

    process {
        $book.sell($owner)
        $book.getBook()
    }
}

function getBook() {
    [cmdletbinding()]
    param (
        [string[]] $title,
        [string[]] $category,
        [string[]] $owner,
        [string[]] $goodreadsKey
    )

    process {
        $goodReadsbook = [GoodreadsBook]::new()
        $book = $goodReadsbook.getInformation($title, $category, $owner, $goodreadsKey)
        $book
    }
}

$mybook = getBook -title "To Kill a Mockingbird" -category "Suspense" -owner "Luke"
$mybook
$mybook.sell("Fred")
$mybook

validatescript-example.ps1

function test {
    [cmdletbinding()]
    param(
        [parameter(mandatory)]
        [validatescript({test-computer $_})]
        [string] $computername
    )

    write-host $computername

}

function test-computer {
    [cmdletbinding()]
    param(
        [parameter(mandatory,valuefrompipeline,position=0)]
        [string] $computername
    )

    $computers = get-adcomputer -filter * | Where-object name -eq $computername
    $computers.name -contains $computername
}

test -computername "WIN10"
test -computername "FIN10"