RubyConf 2014: Rapidly Mapping JSON/XML APIs in Ruby

Whether you are using a 3rd party or custom JSON API service, integration into an existing application can be time consuming: Where do you start? How can you build an object relational model that can adapt to changes in the schema?

In this talk we'll start with an existing JSON schema and build a Ruby adapter to provide a pure Ruby interface to: consume, modify and re-export that schema into JSON and XML.

Transcript

1. Rapidly Mapping APIs
2. github.com/CodingZeal/RubyConf2014
3. Consume Coerce Consolidate
4. Consume Coerce Consolidate
5. Connection: Relationship Manager
6. Connection Resource HTTP GET/POST
7. https://www.googleapis.com/civicinfo/v1/elections?key=<YOUR_API_KEY>
8. https://www.googleapis.com/civicinfo/v1/elections?key=<YOUR_API_KEY>
9. class Connection include HTTParty DEFAULT_API_VERSION = "2" DEFAULT_BASE_URI = "https://www.googleapis.com/civicinfo" base_uri DEFAULT_BASE_URI # ... end
10. class Connection # ... def initialize(options={}) @api_version = options.fetch(:api_version, DEFAULT_API_VERSION) end # ... endd
11. https://www.googleapis.com/civicinfo/v1/elections?key=<YOUR_API_KEY>
12. class Connection include HTTParty DEFAULT_API_VERSION = "2" DEFAULT_BASE_URI = "https://www.googleapis.com/civicinfo" DEFAULT_QUERY = {} base_uri DEFAULT_BASE_URI def initialize(options={}) @api_version = options.fetch(:api_version, DEFAULT_API_VERSION) @query = options.fetch(:query, DEFAULT_QUERY) end def query(params={}) @query.update(params) end # ... end
13. connection = Connection.new( api_version: “2” ) connection.query( key: “qwerty12345” )
14. Client: Routing and Collection
15. Connection Application Client
16. class Client def initialize(options={}) @connection = options.fetch(:connection) @routes = options.fetch(:routes) end end
17. https://www.googleapis.com/civicinfo/v1/elections?key=<YOUR_API_KEY>
18. # GET /elections { elections: { method: "get", path: "/elections" } }
19. connection = Connection.new connection.query( key: “qwerty12345” ) routes = { elections: { method: "get", path: "/elections" } } client = Client.new(connection: connection, routes: routes)
20. client.elections # ???
21. class Client # ... def method_missing(method) # => :elections route_map = routes.fetch(method) http_method = route_map.fetch(:method) # => "get" relative_path = route_map.fetch(:path) # => "/elections" # call the connection for records @connection.send(http_method, relative_path) end # ... end
22. # client.elections { "kind" => "civicinfo#electionsQueryResponse", "elections" => [{ "id" => "2000", "name" => "VIP Test Election", "electionDay" => "2015-06-06" }] }
23. Consume Coerce Consolidate
24. Representation: Entity mapping
25. Application Client Representation Class Instance Hash Instance
26. Representation { “id" => "2000", “name" => "VIP Test Election", “electionDay" => "2015-06-06" } #<User:0x0000 @id="2000", @name="VIP Test Election”, @electionDay=“2015-06-06”>
27. require "ostruct" class Representation < OpenStruct end
28. Consume Coerce Consolidate
29. require "ostruct" class Representation < OpenStruct attr_reader :parent, :children def initialize(representation={}, parent=nil) super(representation) @parent = parent @children = [] bind_parent(parent) represent_children(representation) end # ... end
30. class Representation < OpenStruct # ... def represent(key, collection, parent=nil) collection = Array(collection) collection.map do |item| definition_class = definition_class_for_key(key) definition_class.new(item, parent) end end def definition_class_for_key(key) definition_class = convert_key_to_class_string(key) Object.const_get(definition_class) rescue NameError Object.const_set(definition_class, Representation) end # ... end
31. class Election < Representation # ... end
32. representation = Representation.new(client.elections)
33. { "kind" => "civicinfo#electionsQueryResponse", "elections" => [{ "id" => "2000", "name" => "VIP Test Election", "electionDay" => "2015-06-06" }] }
34. #<Representation kind="civicinfo#electionsQueryResponse", elections=[ #<Election id="2000", name="VIP Test Election”, electionDay=“2015-06-06”>]>
35. Mutability
36. { "id" => "2000", "name" => "VIP Test Election", "electionDay" => "2015-06-06", "locations" => { "street"=> "111 Main St.", "city" => "Medford", "state" => "Oregon", "zipcode" => "97501" } }
37. class Election < Representation def address [self.street, self.city, self.state, self.zipcode].join(' ') end end
38. class Election < Representation include ActiveModel::Validations end
39. Flexibility
40. Representable Take an object and decorate it with a representer module, render a JSON, XML or YAML document from that object. You can also use representers to parse a document and create or populate an object. https://github.com/apotonick/representable#representable
41. @AdamCuppy
42. Thank You!
43. Catch Changes Release Patches
44. { "kind" => "civicinfo#electionsQueryResponse", "elections" => [{ "id" => "2000", "name" => "VIP Test Election", "electionDay" => "2015-06-06", "locations" => { "address" => "111 Main St. Medford, Oregon 97501" } },{ "id" => "2000", "name" => "VIP Test Election", "electionDay" => "2015-06-06" }] }
45. elections[0][“locations”][“address”] elections[1][“locations”][“address”]
46. elections.rb:12:in `<main>': undefined method `[]' for nil:NilClass (NoMethodError)
47. elections[1][“locations”]
48. elections[1].fetch(“locations”)
49. elections.rb:12:in `fetch': key not found: "location" (KeyError)
50. .fetch(“locations”, { address: “Not determined” })