Question:
I am trying to create a new variable that would use other variable with dynamic name as its value. Here’s what I am trying to do:
I have a System.Array with two values:
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$Years = 2015, 2016 |
Another variable, $Transactions
has a list of various transactions.
I am trying to use each of those $Years values in the following way:
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foreach ($Year in $Years){ New-Variable -Name "Transactions_$Year" -Value $Transactions | Where {$_.Date -like "*.$Year"} } |
Now what I would like to do (within that same foreach
loop) is to use that $Transactions_$Year
value when I am creating a another new variable, like this:
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New-Variable -Name "Income_$Year" -Value $Transactions_$Year | Where {$_.Amount -NotLike "-*"} | Measure-Object Amount -Sum | Select -ExpandProperty Sum |
Is this possible, or do you have any alternative ways how I could achieve this?
Answer:
First of all, your New-Variable
invocation doesn’t do what you think it does, as you’d pipe the output of New-Variable
to Where-Object
instead of using the value of $Transactions | Where ...
as value for the variable. You need parentheses for that to work:
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New-Variable -Name "Transactions_$Year" -Value ($Transactions | Where {$_.Date -like "*.$Year" }) |
If you absolutely have to use this approach, then you can get the variables again via Get-Variable
:
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Get-Variable Transactions_$Year | % Value |
However, multiple variables with magic names is a rather poor way of solving this. You probably rather want a map:
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$TransactionsPerYear = @{} $Years | ForEach-Object { $TransactionsPerYear[$_] = $Transactions | Where Date -like "*.$_" } |
And you can get all transactions for 2015 with $TransactionsPerYear[2015]
.
Another way is Group-Object
which doesn’t even require a list of possible years to begin with, but groups a number of objects by some property or expression result:
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$TransactionsPerYear = $Transactions | Group-Object { [int]($_.Date -replace '.*\.') } |
(This is a guess on how it could work. It seems like your date string contains something up to a period, after which there is the year and nothing else, so perhaps something like dd.MM.yyyy
date format.