Event 3: My way…

Looks like we just passed mid-point in Scripting Games 2013, at least for fun part: writing scripts. I must say that I really couldn’t find anything that I’ve seen as “learning experience” in this one – we already did more complex WMI reporting in previous event. We were requested to create very basic HTML report, and we have cmdlet for that. So… I guess I just went lazy with this one. No real error checking, because design claims all have been taken care of. Sweet.

Beginner

I decided to run single command, with some code nested. It looks much better in newest ISE than it looks on my blog, so first “external” piece: part that will generate elements that do not depend on the data from targeted server:

ConvertTo-Html -Title 'Drive Free Space Report' -Body @"
<h2>Local Fixed Disk Report</h2>
$(
    'Code to generate report table'
)
<hr>
$(Get-Date)
"@ | Set-Content Report.html            

The actual code that will run within sub-expression (and will convert data from server to HTML table) is using the same cmdlet, with –Fragment switch this time around:

Get-CimInstance -ComputerName $env:COMPUTERNAME -ClassName Win32_LogicalDisk -Filter 'DriveType = 3' |            
    Select @{            
        Name = 'Drive'            
        Expression = {            
            $_.DeviceId            
        }            
    }, @{            
        Name = 'Size (GB)'            
        Expression = {            
            "{0:N2}" -f ($_.Size / 1GB)            
        }            
    }, @{            
        Name = 'FreeSpace (MB)'            
        Expression = {            
            "{0:N2}" -f ($_.FreeSpace / 1MB)            
        }            
    } | ConvertTo-Html -Fragment            

And that’s it. I’ve added Invoke-Item to look at my results, but that’s not really part of the solution. So you won’t find it here…

Advanced

For advanced category I decided to do two things: make reporting part a separate function (in case I would one day decide that csv is better option than ugly html ), and output reference to files created (e.g. if I want to move them, or copy them, or attach them to mail, or invoke to see them in browser). And because I’m using CIM – I written it in v3 style. Obviously, I’ve included #requires directive there…

To make code easier to understand I’ve used trick that I learned from mjolinor: changing order of begin, process and end block…:

function New-DiskReport {            
[OutputType('System.IO.FileInfo')]            
param (            
)            
            
process {            
    foreach ($Computer in $ComputerName) {            
        $ReportPath = "$Path\$Computer.html"            
        $Table = Get-DiskInventory -ComputerName $Computer |            
            ConvertTo-Html -Fragment | Out-String            
        $Report -f $Computer, $Table, (Get-Date) |            
            Out-File $ReportPath            
        Get-Item $ReportPath            
    }            
}            
            
begin {            
    <# 
        Define:
        -- Get-DiskInventory function
        -- $Report 'template'
    #>            
}            
}            

I don’t use end block at all, and begin is used for initialization: define internal function, and herestring that will work as HTML template. This way function logic goes first, and configuration pieces are down-there, almost like it would be some compiled language.

As you can see I’m vocal about type that will go out, and I do what I promised: I output FileInfo objects for each report generated. I won’t go into details how Get-DiskInventory function looks like, it’s basically code for beginners with pipeline support and parameters defined. Template is also similar, but with “bonus” name of computer included:

$Report = ConvertTo-Html -Title $Title -Body @'
<h2>Local Fixed Disk Report: {0}</h2>
{1}
<hr>
{2}
'@            

With that template created in begin block all I have to do for each computer inventoried is to pass correct set of parameters to –f operator:

$Report -f $Computer, $Table, (Get-Date)

Finally, once I complete reporting, I can do something with results. E.g. if I want to open all reports generated in the browser:

echo DC, CoreDC, CoreFile | New-DiskReport | Invoke-Item

And as it was the case previously, OutputType will help me work with objects I got. I won’t have to remember names of properties – they will be handed to me by PowerShell based on type I declared. As always: feel free to tell me what I did wrong. And now – I can start looking at your entries, to find out what went wrong this time on my own…

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