Creating an Array of Dates within a Date Range with PowerShell

Today I needed to create an array of all the dates in a data range in PowerShell. It’s a simple little thing. Maybe I should have asked Github Copilot, but I’m old skool, so I wrote it myself. (I also haven’t gotten used to having a virtual assistant!)

The reason I even needed to do this is the dread 5000 item view threshold in SharePoint lists and libraries. We have a list with about 1.6 million items in it, and I wanted to “slice out” the ones which matched a specific date range. No matter how I tried to do that in the UI, I failed – not surprisingly, since there are about 1500 items per date.

You might ask why we’d have so many items in a list. Well, this is a list that’s built up over 7 years, and we actually need all the data in it together. I built an app in Angular years ago which uses it as a data source, and that app works just fine. This request for a year’s worth of data is an anomaly, and not something I considered in my design.

I hit on the idea to use PnP.PowerShell to grab the items for each day in the date range and combine them all together. But first, I needed a valid list of all the dates in that year range. Thus, my little script here. I think it’s self-explanatory, but feel free to ask questions in the comments. One note: you could change the format in line 11 to meet your own needs.

# Set up list of days we want
$days = @() # Array to hold all the dates
# Start and end date for the range
$startDate = [DateTime] "2022-05-01" 
$endDate = [DateTime] "2023-04-30"

# Loop through, adding one date to the array at a time until we reach the end date
$date = [DateTime] $startDate
while ($date -le $endDate) {
    $days += $date.ToString('yyyyMMdd')
    $date = $date.AddDays(1)
}

# And here's our final array!
$days