Powershell: How to create a JSON in the GeoJSON structure - json

Question

I'm having problems creating a GeoJSON file. I'm looping through video files extracting info such as datetaken, name, coordinates, etc. I want to write this data to a JSON file so I can plot them on googlemaps. But I'm stuck. I can't get the lat/lng in the correct json format.
The GeoJSON structure is as follows:
"features": [{
"type": "Feature",
"geometry": {
"type": "Point",
"coordinates": [125.6, 10.1]
},
"properties": {
"name": "Lost Islands"
}
]}
My code, no matter what I try, generates the following or something similar.
"features": [{
"type": "Feature",
"geometry": {
"type": "Point",
"coordinates": "System.Collections.Hashtable"
},
"properties": {
"name": "Lost Island"
}
]}
My code (simplified for here):
cls
$dirName = "C:\temp"
$filter = "*.mp4"
$jsonBase = #{}
$features = New-Object System.Collections.ArrayList
$coordinatesList = New-Object System.Collections.ArrayList
$coordinates = New-Object System.Collections.ArrayList
$geometry = New-Object System.Collections.ArrayList
Get-ChildItem $dirName -include $filter -recurse -File | foreach {
$lat = 10.12345
$lng = 20.12345
$vidDate = "2022-09-11T12:00:00.000000Z"
$coordinatesList = New-Object System.Collections.ArrayList
$coordinatesList.Add(#{$lat=$lng;})
$coordinates = New-Object System.Collections.ArrayList
$coordinates.Add(#{"coordinates"=$coordinatesList})
$geometry = #{}
$geometry.Add("coordinates",$coordinates)
$geometry.Add("type","Point")
$features.Add(#{"geometry"=$geometry;
"type" = "Feature";
"properties" = #{"fileName"=($_).Name;"pathToFile"=($_).FullName;"takenDate"=$vidDate;}
})
}
$jsonBase.Add("features",$features)
$jsonstring = $jsonBase | ConvertTo-Json -Depth 3
Write-Host $jsonstring
Any thoughts on where I'm going wrong?

Answer 1

Thanks to mclayton for spotting the depth mistake.
I still had to make a small change to get it in the correct format. Here's the final code:
cls
$dirName = "C:\temp"
$filter = "*.mp4"
$jsonBase = #{}
$features = New-Object System.Collections.ArrayList
$geometry = New-Object System.Collections.ArrayList
Get-ChildItem $dirName -include $filter -recurse -File | foreach {
$lat = 10.12345
$lng = 20.12345
$vidDate = "2022-09-11T12:00:00.000000Z"
$geometry = #{}
$geometry.Add("coordinates",($lat,$lng))
$geometry.Add("type","Point")
$features.Add(#{"geometry"=$geometry;
"type" = "Feature";
"properties" = #{"fileName"=($_).Name;"pathToFile"=($_).FullName;"takenDate"=$vidDate;}
})
}
$jsonBase.Add("features",$features)
$jsonstring = $jsonBase | ConvertTo-Json -Depth 10
Write-Host $jsonstring

Answer 2

The issue is in this line:
$coordinatesList.Add(#{ $lat = $lng })
$lat will become a double type Key on your hashtable and ConvertTo-Json only allows string type keys, probably you got this error but didn't notice it:
$lat = 10.12345
$lng = 20.12345
#{ $lat = $lng } | ConvertTo-Json
Errors with
The type 'System.Collections.Hashtable' is not supported for serialization or deserialization of a dictionary. Keys must be strings.
But also, looking at your expected Json, you most likely wanted coordinates to be an array instead of a key / value pair. Here is a streamlined version of your code:
#{
features = #(Get-ChildItem $dirName -Filter $filter -Recurse -File | ForEach-Object {
$lat = 10.12345
$lng = 20.12345
$vidDate = "2022-09-11T12:00:00.000000Z"
[ordered]#{
type = 'Feature'
geometry = [ordered]#{
type = 'Point'
coordinates = $lat, $lng # Should be Array Here
}
properties = [ordered]#{
fileName = $_.Name
pathToFile = $_.FullName
takenDate = $vidDate
}
}
}
)} | ConvertTo-Json -Depth 99