adding data or modifying data in powershell - csv

Question

I have a CSV file with users and dates in it.
I want to run a powershell script that will modify or add to that list.
I have the modify part down, but I can't get the script right to add a line.
Here is what I have.
The file is users.csv with the following data:
Username Date
Johnson 3/10/16
Smith 12/31/15
Brown 3/9/16
When the script runs, I want to check the username. if there is a match, update the date. if there isn't a match add a new line.
Here is my code:
Get time parts
$date=Get-Date -format d
Get username
$user=$env:username
import data and modify
($CSV= import-csv c:\users.csv -delimiter ',') | foreach {
if ($_.username -match $user) {
$_.date=$date
}
}
output
Export-csv c:\users.csv -notypeinformation -force
This will change the date for a user and export the file just fine.
I can't get the code write to read all the usernames and if there isn't a match to add a line at the end with a username and date.
I'm fairly new to powershell.
Thanks for your help
Charles

Answer 1

try this:
$date = Get-Date -format d
$user = $env:username
$csv = ipcsv c:\users.csv
$csv | % {if ($_.username -match $user) {$_.date = $date}}
if ($user -notin $csv.username) {$csv += [pscustomobject]#{Username = $user; Date = $date}}
$csv