Opal::GoogleMaps

Ruby bindings for client-side Google Maps integration via Opal and helpers for server-side loading.

Add this line to your application's Gemfile:

gem 'opal-google_maps'

And then execute:

$ bundle

Since this gem is a Ruby interface for Google Maps, it requires that the Google Maps JS library be loaded (from Google) first. This is as simple as putting the following line in your server-side application's view template:

<%= Opal::GoogleMaps.google_maps(YOUR_API_KEY) %>

This will add a <script> tag to the rendered HTML with your API key.

If you're using this gem with Clearwater, you'll want to render it into a Clearwater::BlackBoxNode rather than a simple Clearwater::Component. The BlackBoxNode gives you callbacks for mount, update, and unmount, but the simpler components do not. For example:

require 'clearwater/black_box_node' # It is not loaded with Clearwater by default
require 'google/maps' # No need for the `opal` namespace

class MyMap
  include Clearwater::BlackBoxNode
  include Google::Maps # So we don't have to namespace every constant

  attr_reader :map

  def node
    # Important to set the dimensions of the map container
    Clearwater::Component.div(style: { width: '600px', height: '600px' })
  end

  def mount(element)
    # Need to delay this one animation frame so the div we specified above is
    # actually in the rendered DOM. Google Maps needs to get the dimensions of
    # the map from a fully rendered DOM node.
    Bowser.window.animation_frame do
      # Similar to the `google.maps.Map` namespace
      @map = Map.new(
        element, # passed into this method
        center: LatLng.new(-34.397, 150.644), # Sydney, NSW, Australia
        zoom: 8,
      )
    end
  end

  # Each time you render a BlackBoxNode, you get a new instance, so you need
  # to copy it across instances if you want to operate on it across renders.
  # If you're only rendering it and never doing anything with it, you can omit
  # this method entirely.
  def update(previous, element)
    @map = previous.map
  end
end

Google Maps has several additional libraries to choose from. To load them, add the libraries key to your server-side rendering call:

<%= Opal::GoogleMaps.google_maps(YOUR_API_KEY, libraries: %w[drawing geometry places visualization]) %>

You can use the async keyword argument to load the Google Maps libraries in a way that will not block rendering.

<%= Opal::GoogleMaps.google_maps(YOUR_API_KEY, async: true) %>

Keep in mind that this can cause problems if your app renders a map immediately on load. If you load Google Maps asynchronously, it isn't guaranteed to be loaded before your app. In such a case, you may get an error saying something to the effect of google is not an object.

Bug reports and pull requests are welcome on GitHub at https://github.com/jgaskins/opal-google_maps. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

The gem is available as open source under the terms of the MIT License.

Everyone interacting in the Opal::GoogleMaps project’s codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.