postgis function macros

gistfile1.ex

defmodule Geo.PostGIS.Functions do
  
  def st_area(geom) do
    quote do: fragment("ST_Area(?)", unquote(geom))
  end
  
  #Example query
  query = from location in Location, limit: 5, select: st_area(location.geom)
  results = Repo.all(query)

end

gistfile2.txt

** (Ecto.Query.CompileError) `st_area(location.geom())` is not a valid query expression.

* If you intended to call a database function, please check the documentation
  for Ecto.Query to see the supported database expressions

* If you intended to call an Elixir function or introduce a value,
  you need to explicitly interpolate it with ^

    (ecto) expanding macro: Ecto.Query.select/3
    test/geo/ecto_test.exs:55: Geo.Ecto.Test."test postgis functions"/1
    (ecto) expanding macro: Ecto.Query.from/2
    test/geo/ecto_test.exs:55: Geo.Ecto.Test."test postgis functions"/1