Unable to generate HTML table from Powershell function - powershell

Question

I have got a powershell function that gets all errors and warnings from the event logs, counts the occurance of each Event ID and returns a Powershell table. THe code that does this is as follows -
function Get-EventLogs {
[System.Collections.ArrayList]$results = #()
#Do you want to enable transcript for logging all output to file?
$enableLogging = $FALSE
$ExportEnabled = $FALSE
# logging
# if you need detailed logging for troubleshooting this script, you can enable the transcript
# get the script location path and use it as default location for storing logs and results
$log = $MyInvocation.MyCommand.Definition -replace 'ps1','log'
$resultPath = $PSScriptRoot + '\'
Push-Location $resultPath
if ($enableLogging)
{
Start-Transcript -Path $log -ErrorAction SilentlyContinue
Write-Host "Logging enabled..."
Write-Host
Write-Host "Powershell version"
$PSVersionTable.PSVersion
$Host.Version
(Get-Host).Version
Write-host
}
$currentCulture = [System.Threading.Thread]::CurrentThread.CurrentCulture
# Configuration
# selected Event log sources
# limit the feedback only to the following logs
$EventLogList = 'System','Application'
#for FIM Health Check the Security log has less signification value and is skipped
#add it to the eventlog list when you need it
#,'Security'
# if the event logs are containing too much data,
#collect x years of logs
$startdate = ((Get-Date).AddDays(-7))
$Count = 0
$Activity = "Checking log properties"
$allEvents = New-Object System.Collections.Hashtable
$Count = 0
$Activity = "Checking log detaills"
foreach ($eventlog in $EventLogList)
{
#$Count += 1
$pct = ($Count / $EventLogList.Count * 100)
$status = $EventLog + " (" + $Count + "/" + $EventLogList.Count +")"
Write-Progress -Activity $Activity -Status $status -PercentComplete $pct
write-host $count"." $eventlog
[System.Threading.Thread]::CurrentThread.CurrentCulture = New-Object "System.Globalization.CultureInfo" "en-US"
# query the event log
# store the data in a hashtable, to avoid new queries
$allEvents = $Null
$allEvents = Get-WinEvent -FilterHashtable #{logname=$eventlog;StartTime=$startdate;level=0,1,2,3,4,5} -ErrorAction SilentlyContinue
#DEBUG if ($eventlog -eq "Application") { $allevents}
if ($allEvents.count -eq 0)
{
$message = "No events for " + $eventlog + "log since "+ $startdate + "."
Write-Host $message
Write-Host
# no data to process, skip processing for current loop
Continue
}
#For events detailed reporting we're only interested in error events
#not interested in informational events (level 0 and 4)
$evtStats = $allEvents | where -Property level -Notin -Value 0,4 | Group-Object id | Sort-Object Count -Descending
$allevents = $Null
#prep export
$exportfile = $resultPath + "_EventIDStats"+ $eventlog + ".csv.txt"
if ($exportEnabled) {$export | Export-Csv $exportfile -NoTypeInformation}
# evtStats has number and ID attribute
# other attributes must be added:
# - errortype name
# - Source
# - errortype name
# for each event id in the event statistics
# display the most recent event
$Activity = "Looking up last event occurrence..."
$i= 0
foreach ($item in $evtStats)
{
$i += 1
$pct = ($i / $evtStats.Count * 100)
$eventID = $item.Name
$status = "EventID: "+ $item.Name
Write-Progress -Activity $Activity -Status $status -PercentComplete $pct
$customobj = "" | select Count,ErrorID,ErrorType,Message
$customobj.Count = $item.Count
$customobj.ErrorID = $item.Name
#get most recent event from the eventID
$id = $item.Name.ToInt32($Null)
[System.Threading.Thread]::CurrentThread.CurrentCulture = New-Object "System.Globalization.CultureInfo" "en-US"
$lastevent = get-winevent -FilterHashtable #{LogName=$eventlog;Id=$id} -MaxEvents 1 -ErrorAction SilentlyContinue
#depending on local settings, query might fail, if it fails reset to local culture
if ($lastevent.LevelDisplayName.Length -eq 0)
{
[System.Threading.Thread]::CurrentThread.CurrentCulture = $currentCulture
$lastevent = get-winevent -FilterHashtable #{LogName=$eventlog;Id=$id} -MaxEvents 1
}
$customobj.ErrorType = $lastevent.LevelDisplayName
$customobj.Message = $lastevent.Message
#prep EventID export
$exportfile = $resultPath + $eventlog +'_EventID_' + $customobj.ErrorID + ".csv.txt"
if ($exportEnabled)
{
$customobj | Export-Csv $exportfile -NoTypeInformation
}
$results += $customobj
}
#display with format
$results | Format-Table -AutoSize
return ,$results
if ($exportEnabled)
{
$exportfile = $resultPath + "_lastEvents_short_" + $eventlog + ".txt"
$results| Format-Table -AutoSize | out-file $exportfile
$exportfile = $resultPath + "_lastEvents_detail_" + $eventlog + ".txt"
$results | out-file $exportfile
}
}
#Write-Output $results | Format-Table -AutoSize
}
I then need to format the output of this function as a HTML table, so I can show it in my report.
$elogs = (Get-EventLogs) | Out-String
The code above outputs it as a long string (to be expected). But I cannot figure out how to format it as a HTML table. THe code that finally generates the report is as follows -
$Report = ConvertTo-Html -Title "$Computername" `
-Head "<center><h1>Server Report for <br><br>$Computername</h1></center><br /><br />" `
-Body "$Heading $Hardware $elogs $PercentFree $Output $Restarted $Services $Stopped $Css" }
Is there a way to output this as a table?

Answer 1

ConvertTo-Html is able to take an object and render that object as a HTML table. For simplicity's sake, I'll include the -Fragment switch that will ONLY return a HTML table (not all the HTML header, etc.).
Take a simple object, such as some basic process data, and you can create a HTML table:
[PS] $p = Get-Process | Select -First 3 -Property Name,ID
[PS] $p | ConvertTo-Html -Fragment
<table>
<colgroup><col/><col/></colgroup>
<tr><th>Name</th><th>Id</th></tr>
<tr><td>Process1</td><td>1888</td></tr>
<tr><td>Process2</td><td>1536</td></tr>
<tr><td>Process3</td><td>13920</td></tr>
</table>
Note that we don't need to specify a -Body with all the variables; we just need to make sure that we have all the data collected in an object (with the appropriate property names) and the cmdlet does the rest.
Going back to your script, there are a few things to look at:
Don't use Write-Host. If you want debug messages, consider using Write-verbose and Write-Debug. You'll need to set the $VerbosePreference and $DebugPreference variables to "Continue" to make this output visible.
Similarly, avoid using Format-Table
Your script returns an object ,$results. You should be able to pipe this into ConvertTo-Html with additional header and body content.
Note finally that the -Body switch doesn't format your object; it just includes extra HTML in front of the HTML table.