paddleman

paddleman

Hello folks.

I am playing around with using a PostGIS enabled database in Livebook (with Maplibre).

I figured out how to add Postgrex types to handle the Geometry type used by PostGIS. However, when trying to reference the results of a query in LiveBook through the following query:

stations = Postgrex.query!(conn, "select * from bc_stns limit 100", [])

then trying to reference a field in the query results:

geo_pts = stations.geom

I get the following error. I am missing something basic, but cannot figure it out.

** (KeyError) key :geom not found in: %Postgrex.Result{
  command: :select,
  columns: ["id", "station_number", "station_name", "prov", "hyd_status",
   "drainage_area_gross", "drainage_area_effect", "geom", "latitude",
   "longitude", "from_year", "to_year", "record_length", "regulated",
   "reg_from", "reg_to", "station_id"],
  rows: [
    [
      4858,
      "07EA001",
      "FINLAY RIVER AT WARE",
      "BC",
      "D",
      11100.0,
      nil,
      %Geo.Point{
        coordinates: {-125.62639, 57.42083},
        srid: 4269,
        properties: %{}
      },
      57.42083,
      -125.62639,
      1960,
      1983,
      23,
      false,
      nil,
      nil,
      4858
    ],

All help is appreciated.

Thanks.
DJ

Most Liked

al2o3cr

al2o3cr

Postgrex.query! returns a single Postgrex.Result value, you’ll need to extract the data from the result’s rows and columns.

Last Post!

jonatanklosko

jonatanklosko

Creator of Livebook

You can also use Table.to_rows(stations) to convert the result to list of maps : )

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