NioGoogleGeocoder

NioGoogleGeocoder is a collection of Elixir convenience functions to geocode a single, or list of, addresses. It also includes a function that automatically adds a geo location to an Ecto.Changeset.

Installation

Add nio_google_geocoder to your list of dependencies in mix.exs:

def deps do
[{:nio_google_geocoder, "~> 0.8.0"}]
end

Usage

Geocoding an address:

.geocode("74 High Street, New Haven, CT, 06520")

will return the following:

{:ok, [%{"address_components" => ..}]}

You can also pass it a list of addresses and the result will be a list of tuples:

[{:ok, [%{"address_components" => ..}]}, {:ok, [%{"address_components" => ..}]} ]

To use a specific API key set it in config:

config :nio_google_geocoder, api_key: "API_KEY"

In case of errors a tuple starting with {:error, error_message} is returned

Ecto.Changeset usage

There is an additional function which you can pass an Ecto.Changeset which will automatically add latitude and longitude based on a list of address fields. It will only geocode if the address attributes are present in the changes map of the changeset.

Geocoding an address in a changeset

To geocode an address in the changeset you need to pass it (changeset, [list of address fields], latitude_field, longitude_field)

ex. add_geo_coordinates_to_changeset(changeset, [:address, :city, :zip], :latitude, :longitude)

It is important to remember that it will only update the geolocation if any of the [list of address fields] change. Otherwise it returns the changeset.

Also pass the list of address fields in logical order ex. [:address, :city, :zip] vs. [:zip, :address, :city] as the values of the field are concatenated for geocoding.

Example in Model

defmodule Location do
  use Ecto.Schema
  import Ecto.Changeset

  schema "locations" do
    field :name, :string
    field :address, :string
    field :city, :string
    field :state, :string
    field :zip, :string
    field :latitude, :float
    field :longitude, :float
  end

  def changeset(user, params \\ :empty) do
    user
    |> cast(params, ~w(name), ~w(address city state zip latitude longitude))
    |> NioGoogleGeocoder.Changeset.add_geo_coordinates_to_changeset([:address, :city, :zip], :latitude, :longitude)
  end
end

ToDO

Allow for the additional params specified here: https://developers.google.com/maps/documentation/geocoding/intro

Version

0.8.0

License

MIT