Powershell - Using ConvertFrom-csv - powershell

Question

I'm brand new to Powershell. I have a variable that contains comma separated values. What I want to do is read each entry in the csv string variable, and assign it to a variable. I am using ConvertFrom-csv to separate the data with headers.
How can I assign each value to a variable, or even better, use ConvertTo-csv to create a new csv string which only has, for example, columns 2/3/6/7 in it?
I would ultimately want to write that data out to a new csv file.
Here is my test code:
#Setup the variable
$Data = "test1,test2,test3,1234,5678,1/1/2021,12/31/2021"
$Data | ConvertFrom-csv -Header Header1,Header2, Header3, Header4, Header5, Header6, Header7
# Verify that an object has been created.
$Data |
ConvertFrom-csv -Header Header1,Header2, Header3, Header4, Header5, Header6, Header7 |
Get-Member
#Show header1
Write-Host "--------Value from $Data----------------------------------------"
$Data[0] #doesn't work, only displays the first character of the string
Write-Host "-----------------------------------------------------------------"

Answer 1

Let me suggest a different approach. If you use ConvertFrom-Csv and assign the result of a variable ($data), this will be an array of Custom Objects. You can run this through a loop that steps through the elements of the array , one at a time, and then through an inner loop that steps through the properties of each object one at a time, setting a variable with the same name as the field header and the same value as the current record's value.
I don't have code that does exactly what you want. But I'm including code that I wrote a few years back that does something similar only using Import-Csv instead of ConverFrom-Csv.
Import-Csv $driver | % {
$_.psobject.properties | % {Set-variable -name $_.name -value $_.value}
Get-Content $template | % {$ExecutionContext.InvokeCommand.ExpandString($_)}
}
Focus on the first inner loop. Each property of the current object will have a name that came from the header and a value that came from the current record of the Csv file. You can ignore the line that says ExpandString. That's just what I choose to do with the variables once they have been defined.

Answer 2

How can I assign each value to a variable, or even better, use ConvertTo-Csv to create a new csv string which only has, for example, columns 2/3/6/7 in it?
This is one way of automating this:
# Define the CSV without headers
$Data = "test1,test2,test3,1234,5678,1/1/2021,12/31/2021"
# Set the number of headers needed
$headers = $Data.Split(',') | ForEach-Object -Begin { $i = 1 } -Process {
"Header$i"; $i++
}
# Set the desired columns we want
$desiredColumns = 2,3,6,7 | ForEach-Object { $_ - 1 } | ForEach-Object {
$headers[$_]
}
# Convert to CSV and filter by Desired Columns
$Data | ConvertFrom-Csv -Header $headers | Select-Object $desiredColumns
Result
Header2 Header3 Header6 Header7
------- ------- ------- -------
test2 test3 1/1/2021 12/31/2021
Result as CSV
$Data | ConvertFrom-Csv -Header $headers |
Select-Object $desiredColumns | ConvertTo-Csv -NoTypeInformation
"Header2","Header3","Header6","Header7"
"test2","test3","1/1/2021","12/31/2021"