Azure Data Explorer SubQuery KQL GeoJson - geojson

Question

I am trying to create a KQL query where I can filter which locations are inside a geojson using function geo_point_in_polygon
I am trying to first, obtain my polygon with this query:
let polygon = adt_dh_FerrovialTwins_westeurope
| where ModelId == "dtmi:ferrovial:domain:models:v1:acopiotemploraltwin;1"
and Key == "localizacion"
| top 1 by Id
|project (Value);
polygon;
And with this data, trying to do another query to filter how many times a location is inside this polygon, with this query
let polygon = adt_dh_FerrovialTwins_westeurope
| where ModelId == "dtmi:ferrovial:domain:models:v1:acopiotemploraltwin;1"
and Key == "localizacion"
| top 1 by Id
|project (Value);
adt_dh_FerrovialTwins_westeurope
| where ModelId == "dtmi:ferrovial:domain:models:v1:camiondetierrastwin;1"
and Key == "localizacion"
| extend lon=(Value).geometry.coordinates[0], lat= (Value).geometry.coordinates[1]
| project todecimal(lon), todecimal(lat), Id
| where geo_point_in_polygon(lon, lat, polygon)
| summarize count() by Id, hash = geo_point_to_s2cell(lon, lat, 7)
| project geo_s2cell_to_central_point(hash), Id, count_
| render piechart with (kind=map) // map rendering available in Kusto Explorer desktop
It says it needs a dynamic value, but it is already one. I don´t know how to solve this, because if I try using a Polygon variable as string (dynamic) it works ok:
let polygon = dynamic({
"type": "Polygon",
"coordinates": [
[
[
-22.6430674134452,
-69.1258109131277
],
[
-22.6430533208934,
-69.1250474377359
],
[
-22.6453362953948,
-69.1243603098833
],
[
-22.6452658337868,
-69.1264980409803
],
[
-22.6431096910912,
-69.1257803741119
],
[
-22.6430674134452,
-69.1258109131277
]
]
]
});
adt_dh_FerrovialTwins_westeurope
| where ModelId == "dtmi:ferrovial:domain:models:v1:camiondetierrastwin;1"
and Key == "localizacion"
| extend lon=(Value).geometry.coordinates[0], lat= (Value).geometry.coordinates[1]
| project todecimal(lon), todecimal(lat), Id
| where geo_point_in_polygon(lon, lat, polygon)
| summarize count() by Id, hash = geo_point_to_s2cell(lon, lat, 7)
| project geo_s2cell_to_central_point(hash), Id, count_
| render piechart with (kind=map) // map rendering available in Kusto Explorer desktop

Answer 1

Here is a minimal, reproducible example:
let polygon = print dynamic({"type": "Polygon","coordinates": []});
print geo_point_in_polygon(0, 0, polygon)
Fiddle
You shared the IntelliSense error:
A value of type dynamic expected
However, you didn't share the run-time error:
Failed to resolve scalar expression named 'polygon'
As the error suggests, the function expects a scalar as an argument.
Your tabular expression can be converted to scalar using the toscalar() function.
let polygon = toscalar(print dynamic({"type": "Polygon","coordinates": []}));
print geo_point_in_polygon(0, 0, polygon)
Fiddle