mobilizon/lib/graphql/schema/custom/point.ex

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2020-01-26 20:34:25 +01:00
defmodule Mobilizon.GraphQL.Schema.Custom.Point do
@moduledoc """
The geom scalar type allows Geo.PostGIS.Geometry strings to be passed in and out.
Requires `{:geo, "~> 3.0"},` package: https://github.com/elixir-ecto/ecto
"""
use Absinthe.Schema.Notation
scalar :point, name: "Point" do
description("""
The `Point` scalar type represents Point geographic information compliant string data,
represented as floats separated by a semi-colon. The geodetic system is WGS 84
""")
serialize(&encode/1)
parse(&decode/1)
end
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@spec decode(Absinthe.Blueprint.Input.String.t()) :: {:ok, term} | :error
@spec decode(Absinthe.Blueprint.Input.Null.t()) :: {:ok, nil}
defp decode(%Absinthe.Blueprint.Input.String{value: value}) do
with [_, _] = lonlat <- String.split(value, ";", trim: true),
[{lon, ""}, {lat, ""}] <- Enum.map(lonlat, &Float.parse(&1)) do
{:ok, %Geo.Point{coordinates: {lon, lat}, srid: 4326}}
else
_ -> :error
end
end
defp decode(%Absinthe.Blueprint.Input.Null{}) do
{:ok, nil}
end
defp decode(_) do
:error
end
defp encode(%Geo.Point{coordinates: {lon, lat}, srid: 4326}), do: "#{lon};#{lat}"
end