I have a JSON configuration that I'm importing and I want to give the script runner the ability to update any fields during a loop. However, I'm hitting a "Collection was Modified; enumeration operation may not execute" error. My approach was to clone the hashtable so I can loop through the clone while modifying the original one, but I still encounter the same error. This happens whether I'm using version 5.1 or 7.5 of Powershell. Here's the relevant code snippet: $conf = Get-Content $PathToJson -Raw | ConvertFrom-Json -AsHashTable $tempConf = $conf.Clone() ... I get the error while executing the foreach loop. Is the clone still referencing the $conf memory due to the nested hashtables?
3 Answers
Totally get your frustration, but for what it’s worth, I’d suggest refining your input process. A consistent schema for the JSON would help a ton! You’ll have fewer headaches by ensuring that your configurations are validated and defined beforehand, avoiding unexpected keys while editing.
Check the documentation on cloning hashtables. The `Clone()` method creates a shallow copy. This works for most values, but if you're dealing with references inside those hashtables, both your clone and the original point to the same object, which causes issues when you modify them. Consider implementing a deep clone method instead or try iterating over a copy of the keys instead of referencing the original hashtable directly. For instance, you could do something like this: foreach ($key in [String[]]$myJsonHashtableObj.Keys) {...}
Got it! Thanks for clarifying that about shallow vs. deep copies. I'll revise my approach by copying the keys.
It seems like you're bumping into issues due to the nested hashtables. A shallow copy won't suffice here. You might want to look into deep cloning strategies. Alternatively, instead of iterating over the keys of the hashtable directly, you could create a new array of keys to loop through, which should help avoid the modification error.
Haha, I love your enthusiasm! I’m working on a standardization process for my PowerShell scripts, and I’m finding it so much more efficient.