How can I verify my keys in my powershell script?

Question

I need to verify my parameters(keys) when I run it. For example, when I set wrong parameters looks like (myscript.ps1 -p1 blabla -p2 blabla) I have error in console(wrong type). How I can throw this error? Also, I need to write logs in different levels(Debug,Error,Warning). I know only one cmdlet Start-Transcript, but it write all actions.

        param
        (
             [datetime]$sleep,
             [datetime]$wake_up
        )   
        #Starting log process
Start-Transcript .\logger.txt -Append
function do_sleep () 
{
    if (!$sleep)
    {
        [datetime]$sleep = Read-Host "Input time when you go to sleep"
    }
    if (!$wake_up)
    {
        [datetime]$wake_up = Read-Host "Input time when you wake up"
    }
    if ($wake_up.Hour -le 8 ) {
        Write-Host "You are lark"
    }
    if ($wake_up.Hour -gt 8) {
        Write-Host "You are owl"
    }
    if ($wake_up -lt $sleep) {
        $sleeping_time = ($wake_up.AddDays(1) - $sleep)
        $normal_sleep = $sleeping_time.hours;
    }
    else {
        $sleeping_time = $wake_up - $sleep;
        $normal_sleep = $sleeping_time.hours;
    }   
    if ($normal_sleep -ge 8 ) {
        Write-Host "You slept more"  $sleeping_time.Hours  "hours. You are lucky man. " 
    }
}
do
{
    try
    {
        do_sleep
        exit
    }
    catch 
    {
        Write-Host ("Wrong input. Please input data again.")
        $g = 1;
    }
}
while ($g -eq 1)
Stop-Transcript

Answer 1

try Something like this:

$ScriptName = "Script1"

try
{

    #create log
    if (![System.Diagnostics.EventLog]::SourceExists($ScriptName))
    {
        New-EventLog -LogName Application -Source $ScriptName
    }


    #Log information
    Write-EventLog –LogName Application –Source $ScriptName –EntryType Information –EventID 1 –Message "Starting..."

    $Test="test1"


    if ($Test -eq "test1") 
    {
    #throw exception 1
    throw "$Test is bad"
    }

    if ($Test -eq "test2") 
    {
    #throw exception 2
    throw "$Test is really bad"
    }

    if ($Test -eq "test3") 
    {
    #Log warning
    Write-EventLog –LogName Application –Source $ScriptName –EntryType Warning –EventID 1 –Message "Starting..."
    }

}
catch 
{
        #log all exceptions 
        $result="Message : {0}, Type : {1}, Exception : {2}, StackTrace : {3}" -f $_, $_.GetType(), $_.Exception, $_.Exception.StackTrace

        Write-EventLog –LogName Application –Source $ScriptName –EntryType Error –EventID 1 –Message $result

        #rethrow if you want print errors to output standard error
        throw
}
finally
{
    #Log information
    Write-EventLog –LogName Application –Source $ScriptName –EntryType Information –EventID 1 –Message "Ending..."
}

Answer 2

To be able to use different logging levels decorate param with the following attribute:

[CmdletBinding()]Param

To validate parameters you can use validation attributes, eg

[ValidateNotNullOrEmpty()] $MyParam

For more information search for 'advanced function PowerShell' or have a look at the snippets that you get when you press Ctrl+J in the PowerShell ISE