Help with PowerShell Array Updates
Asked by
TechieNomad42
I'm working on a script where I'm iterating through a list of servers to get specific metrics and trying to store those values in an array. While the initial iteration works fine and displays the metrics, I encounter an error on the second loop when I attempt to update the array. Here's a snippet of what I'm using to create or update the array:
`$results += [PSCustomObject]@{`
`Server=$server`
`Metric=$metricKey`
`Value=$metricValue`
`}`. Any suggestions on how to fix this issue?
Answers
It sounds like you're missing the initialization of the array. Before you start adding items, make sure you've initialized it with `$results = @()`. If you're running this inside a loop, consider using a `foreach` loop instead of `+=` to avoid performance issues. This way, you can build the array without resizing it every time.
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You should definitely include the error message you're getting when things fail. That can provide crucial insights. Also, sharing the entire script might help others identify the exact issue, though I understand if you can't due to work restrictions.
TechieNomad42: Good point! I fixed the catch to output the error message. It says: Method invocation failed because [System.Management.Automation.PSObject] does not contain a method named 'op_Addition'.
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Using `+=` isn't the best practice for building arrays in PowerShell, especially for larger datasets. Instead, consider creating the array directly in the loop like this:
`$arrayVar = @(
foreach ($thing in $things) {
[pscustomobject]@{
Server = $server
Metric = $metricKey
Value = $metricValue
}
}
)`
This approach is more efficient.
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Have you double-checked if you've run `$results = @()` to initialize the array? It’s a common mistake that can lead to the issues you're facing.
TechieNomad42: Argggghhhh! I always forget to initialize. Thank you!
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TechieNomad42: Boom, initialization is what I missed! Thanks for pointing that out. I'll try the `foreach` method you suggested since I'm actually doing nested loops.