How to use Geo library to create valid Ecto Model changeset?

According to the tests for the library:

https://github.com/bryanjos/geo/blob/351ee6c4f8ed24541c9c2908f615e7b0a238f010/test/geo/ecto_test.exs#L100

You need to pass a Geo.Point to your changeset function:

changeset = Place.changeset(%Place{}, %{coordinates: %Geo.Point{coordinates: {49.44, 17.87}})

You can read more about custom ecto types in [the docs].(https://hexdocs.pm/ecto/Ecto.Type.html#content)