google_maps_juice

GoogleMapsJuice

Drink Google Maps Services with ease! :tropical_drink: :earth_americas:

This gem aims at progressively covering a fair amount of those widely-used services that are part of the Google Maps Platform, such as: Geocoding, Time Zone, Directions, etc. with some key ideas:

1. Allowing "standard" requests, meaning: sending the same params documented by Google.
2. Allowing "smart" requests, meaning: with more "developer-friendly" params, and/or improved error handling.
3. Return full Google responses, but also provide methods to easily inspect the most relevant info.
4. Provide error handling.

GoogleMapsJuice currently covers:

• Geocoding
• Time Zone
• Directions

Contributors are welcome!

Installation

Add this line to your application's Gemfile:

gem 'google_maps_juice'

And then execute:

$ bundle

Or install it yourself as:

$ gem install google_maps_juice

Google API Key

You can set your Google API key with the following one-liner:

GoogleMapsJuice.configure { |c| c.api_key = 'my-api-key' }`

In a Rails application, that would typically go in an initializer.

Multiple API keys

If you need to use multiple API keys, you have two options:

• a) pass an api_key named param to the endpoint class method, e.g.

GoogleMapsJuice::Geocoding.geocode(params, api_key: 'my-api-key')

• b) create your own GoogleMapsJuice::Client instance(s) and use it to create your endpoint object(s), e.g.

client = GoogleMapsJuice::Client.new(api_key: 'my-api-key')
geocoding = GoogleMapsJuice::Geocoding.new(client)
response = geocoding.geocode(params)

This is especially useful in some "hybrid" scenario, where an API key is shared by a group of requests, but another group uses a different key: a client object would then be instantiated and reused for each group.

Error Handling

If Google servers respond with a non-successful HTTP status code, i.e. 4xx or 5xx, a GoogleMapsJuice::ResponseError is raised with a message of the form 'HTTP 503 - Error details as returned by the server'.

API errors are also handled, based on the status attribute of Google's JSON response, and the optional error_message attribute.

• GoogleMapsJuice::ZeroResults is raised when status is 'ZERO_RESULTS'
• GoogleMapsJuice::ApiLimitError is raised when status is 'OVER_DAILY_LIMIT' or 'OVER_QUERY_LIMIT'
• GoogleMapsJuice::ResponseError is raised when status is not OK with a message of the form API <status> - <error_message>

Geocoding

Standard Geocoding

The simplest geocoding requests accept an address:

response = GoogleMapsJuice::Geocoding.geocode(address: '8955 Lantana Rd, Lake Worth, FL 33467, USA')

Supported params are the ones accepted by Google's endpoint: address, components, bounds, language, region; at least one between address and components is required. Learn more here. GoogleMapsJuice will raise an ArgumentError if some unsupported param is passed, or when none of the required params are passed.

Smart Geocoding

Motivation

For best geocoding results, the address param should be formatted according to the local language. This is often a hard task for an application that needs to geocode addresses stored as separate fields. Luckily, Google offers the components param which accepts individual address fields; however, it's annoying to build it and it's not fault tolerant. For example, an error on postal_code makes geocoding of a whole address fail.

Purpose of i_geocode method is twofold:

1. Providing a simpler method interface for leveraging Google's components param
2. Providing an approximate geocoding result when some address component is wrong

Here an example call with all supported params:

response = GoogleMapsJuice::Geocoding.i_geocode(
  {
    address: '8955 Lantana Rd',
    locality: 'Lake Worth',
    administrative_area: 'FL',
    postal_code: '33467',
    country: 'US'
  }, sleep_before_retry: 0.15
)

Accepted params:

• At least one between address and country is required
• locality, administrative_area, postal_code and country expect the same content as described in Component Filtering
• address can also include more info than street number and name, as long as they do not contrast with other params passed
• An optional sleep_before_retry param sets seconds between geocoding attempts (see below); defaults to zero.
• GoogleMapsJuice will raise an ArgumentError if some unsupported param is passed, or when none of the required params are passed.

How it works

On its 1st attempt, i_geocode sends all received params to Google's endpoint, properly formatted. If a GoogleMapsJuice::ZeroResults is raised, it removes a param and retries until no error is raised. Params are removed in the following order:

• postal_code
• address
• locality
• administrative_area

As a consequence:

• In the best case, i_geocode will send 1 request to Google API
• In the worst case, i_geocode will send 4 requests to Google API

Geocoding Response

Both geocode and i_geocode methods return a GoogleMapsJuice::Geocoding::Response. It's a Hash representation of Google's JSON response. However, it also provides many useful methods:

• latitude, longitude: geographic coordinates as float numbers

• street_number, route, locality, postal_code, administrative_area_level_1, country: all of these methods return a Hash with 2 keys: 'short_name' and 'long_name'

• partial_match?: boolean, true if some param (of the last geocoding attempt) partially matched

• precision: can be one of: 'street_number', 'route', 'locality', 'postal_code', 'administrative_area_level_1', 'country' and represents the most-specific matching component

Time Zone

Google's Time Zone API returns the time zone of a given geographic location; it also accepts a timestamp, in order to determine whether DST should be applied or not.

GoogleMapsJuice provides the GoogleMapsJuice::Timezone.by_location method. Compared to Google's raw API request, it provides simpler params and some validations, in order to avoid sending requests when they would fail for sure (and then save money!) - to learn more see spec/unit/timezone_spec.rb.

Accepted params:

• Both latitude and longitude are mandatory
• timestamp is optional and defaults to Time.now
• language is optional

Time Zone Response

The by_location method returns a GoogleMapsJuice::Timezone::Response. It's a Hash representation of Google's JSON response. However, it also provides a few useful methods:

• timezone_id: unique name as defined in IANA Time Zone Database

• timezone_name: the long form name of the time zone

• raw_offset: the offset from UTC in seconds

• dst_offset: the offset for daylight-savings time in seconds

Directions

Google's Directions API returns the possible routes of given origin and destination geographic locations; Google's API accepts address, textual latitude/longitude value, or place ID of which you wish to calculate directions. Currently this gem implements only latitude/longitude mode. GoogleMapsJuice will raise an ArgumentError if some unsupported param is passed, or when none of the required params are passed.

response = GoogleMapsJuice::Directions.find(origin: '41.8892732,12.4921921', destination: '41.9016488,12.4583003')

Compared to Google's raw API request, it provides validation of both origin and destination, in order to avoid sending requests when they would fail for sure - to learn more see spec/unit/directions_spec.rb.

Accepted params:

• Both origin and destination are mandatory
• origin is composed by latitude and longitude, comma separated float values
• destination same format as origin

Directions Response

The find method returns a GoogleMapsJuice::Directions::Response. It's a Hash representation of Google's JSON response. However, it also provides a few useful methods:

• results: the Hash raw result

• routes: an Array of GoogleMapsJuice::Directions::Response::Route objects

• first: the first Route of the routes List

As described in Google's Directions API, the response contains all possible routes. Each route has some attributes and one or more legs, wich in turn have one or more steps. If no waypoints are passed, the route response will contain a single leg. Since GoogleMapsJuice::Directions doesn't handles waypoints yet, only the first leg is considered for each route. The GoogleMapsJuice::Directions::Response::Route is a representation of a response route and provides methods to access all route's attributes:

• summary: a brief description of the route

• legs: all legs of the route, generally a single one

• steps: all steps of the first route's leg

• duration: time duration of the first route's leg

• distance: distance between origin and destination of first route's leg

• start_location: latitude/longitude of the origin first route's leg

• end_location: latitude/longitude of the destination first route's leg

• start_address: address of the origin first route's leg

• end_address: address of the destination first route's leg

Development

After checking out the repo, run bin/setup to install dependencies. Create a .env file and save your Google API key there; if you want to use a different key for testing, put it in .env.test and it will override the one in .env.

Run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags and push the .gem file to rubygems.org.

Implementing a new endpoint

All endpoints must be subclasses of GoogleMapsJuice::Endpoint; methods that implement "standard" Google API calls have a common structure, described by the invoke method in the SomeEndpoint test class in spec/unit/endpoint_spec.rb.

All new endpoints' methods must return subclasses of GoogleMapsJuice::Endpoint::Response as their response objects, since it contains methods needed for error handling.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/algonauti/google_maps_juice.

License

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