I imported a CSV file with `$data = Import-Csv -Path "path\to\file.csv"` and loop through the resulting collection. I can read individual values with expressions such as `$data.OffLastName[$jj]`, `$data.ReportsToLast[$jj]`, and `$data.ManagerID[$jj]`. However, assigning a new value does not seem to update the original data:
`$Manager = "Manager"`
`$data.ManagerID[$jj] = $Manager`
`$data.ManagerID[$jj]`
The assignment runs without an obvious error, but the final lookup still returns the previous value, such as `$null` or a placeholder string. What is the correct way to modify the `ManagerID` property on the object at index `$jj`?
3 Answers
Index the collection first, then assign the property on that individual object:
`$data[$jj].ManagerID = $Manager`
When you write `$data.ManagerID`, PowerShell uses member-access enumeration to produce a separate list of all the `ManagerID` values. Indexing that list does not directly target the corresponding object inside `$data`, so changing it does not update the imported CSV objects.
The capitalization of a property usually is not the problem here—PowerShell property names are generally case-insensitive. The important distinction is the order of indexing and property access: use `$data[$jj].ManagerID`, not `$data.ManagerID[$jj]`. The first selects one CSV object and changes its property; the second selects an item from an enumerated property-value collection.
The assignment is actually succeeding, but it is being applied to the temporary array created by member-access enumeration. For example:
`$ids = $data.ManagerID`
`$ids[$jj] = $Manager`
`$ids` will show the changed value, while `$data` remains unchanged. To persist the update, modify the object directly with `$data[$jj].ManagerID = $Manager`. This is also safer because the number of values returned through property enumeration is not always guaranteed to match the number of source objects.
That worked. I was confusing the list of property values with the original collection. So `$data[$jj].ManagerID` targets the object at that index, while `$data.ManagerID[$jj]` indexes the separately enumerated property values.