Question:  I need some help with a Powershell Function to generate some text output based on some imput parameters . Can you supply an example of a Powershell function or possibly including calling a function from within a function

Answer: This is a general question , but here is an example of utilising a function using the Powershell syntax. The concept is a general programming construct . In the example below there are  2 functions - GetNewDatabaseDetails   & Get-RandomPassword  .       

Don't worry about the purpose of the function - it's part of a larger script to generate code , the main point is that the function is referenced and called from different parts of the code. 

At the bottom of the script you'll see the line  "GetNewDatabaseDetails $mydb"   - It's calling the   GetNewDatabaseDetails function , which generates a bunch of text for creating a PostgreSQL database.   In the middle of the GetNewDatabaseDetails there is a reference to the Get-RandomPassword  function. 

Generally - if you're finding yourself reusing Powershell code & making slight modifications - then there is possibility it's a candidate to be converted into a function

##Input parameter
param (
    [string]$mydb = ""
    
)


#Purpose generate a new CREATE DATABASE 
Function GetNewDatabaseDetails([string]$dbname)
{

$dbname = $dbname;
$userfull = $dbname + "_full"
$usefullpw = Get-RandomPassword 8 
$userread= $dbname + "_read"
$usereadpw = Get-RandomPassword 8 
$fullcreatedb = @"

###############START  CREATE DB DETAILS: $dbname#####################

CREATE DATABASE $dbname;
\c $dbname
CREATE SCHEMA $dbname;

CREATE USER $userread WITH ENCRYPTED PASSWORD '$usefullpw';
GRANT  CONNECT ON DATABASE $dbname  TO $userread;
GRANT  USAGE   ON SCHEMA $dbname  TO $userread;
GRANT SELECT ON ALL TABLES IN SCHEMA $dbname TO $userread;
ALTER USER $userread SET search_path TO $dbname;


CREATE USER $userfull WITH ENCRYPTED PASSWORD '$usereadpw';
GRANT  CONNECT ON DATABASE  $dbname TO $userfull;
GRANT  USAGE,CREATE   ON SCHEMA $dbname  TO $userfull;
GRANT SELECT, INSERT, UPDATE, DELETE ON ALL TABLES IN SCHEMA $dbname TO $userfull;
ALTER USER $userfull SET search_path TO $dbname;

## username/password  
$dbname
$userread / $usereadpw
$userfull / $usefullpw


###############FINISH  CREATE DB DETAILS: $dbname#####################
"@

          
return $fullcreatedb 
    
}
  

function Get-RandomPassword {
    param (
        [Parameter(Mandatory)]
        [int] $length
    )
    #$charSet = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789{]+-[*=@:)}$^%;(_!?>/|.'.ToCharArray()
    $charSet = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789'.ToCharArray()
    $rng = New-Object System.Security.Cryptography.RNGCryptoServiceProvider
    $bytes = New-Object byte[]($length)
 
    $rng.GetBytes($bytes)
 
    $result = New-Object char[]($length)
 
    for ($i = 0 ; $i -lt $length ; $i++) {
        $result[$i] = $charSet[$bytes[$i]%$charSet.Length]
    }
 
    return (-join $result)
}




##example

GetNewDatabaseDetails $mydb

Full credit for the Get-RandomPassword  function goes to arminreiter.com  

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