mkcode/api_cached_attributes_examples

Simple example app explaining api_cached_attributes

README

Example application for api_cached_attributes.

Install

This is a standard Rails 4.2 application using sqlite.

git clone git@github.com:mkcode/api_cached_attributes_examples.git
cd api_cached_attributes_examples
bundle install
bin/rake db:migrate

bin/rails console

 # or

bin/rails server

Play

1. Start a server and navigate to locahhost:3000/github_users. A standard rails scaffolding is here.
2. Click on 'New Github User'.
3. Enter a user's github identifier (their github username).
4. Watch the auto-population magic

Learn

The commit log in this application is very concise and minimal. Please look through it and see how this example was created.

The meat and potatoes are as follows:

In app/api_attributes/github_user_attributes:

class GithubUserAttributes < ApiCachedAttributes::Base
  client { Octokit::Client.new }

  default_resource { |client, scope| client.user(scope[:github_login]) }

  attribute :id
  attribute :avatar_url
  attribute :url
  attribute :html_url
  attribute :type
  attribute :name
  attribute :company
  attribute :email
  attribute :public_repos
  attribute :updated_at
  attribute :created_at
end

We define a number of attributes that are part of the github v3 user API. See: https://developer.github.com/v3/users/#get-a-single-user

The scope is sent into both the client and the resource blocks. In this case, we are using an anonymous client and simply using the github_login scope as the paramater to the user endpoint. In a more advanced example (not shown), we may use a user's oauth_token as the scope create an authenticated client from that.

Then, in app/models/github_user:

class GithubUser < ActiveRecord::Base
  validates :github_login, presence: true, uniqueness: true

  api_cached_attributes :github_user, scope: :github_login,
    attributes_map: { id: :github_id, updated_at: :github_updated_at,
                      created_at: :github_created_at }
end

We call api_cached_attributes to include the previously defined attributes in the GithubUser model to create a hybrid domain object. This is partially backed by the database, and partially backed by the Github API.

We scope: github_login option, collects the value of github_login on this model and sends this into the GithubUserAttributes class to make a unique client and resource. It does not need to be persisted (saved) to work.

The attribues_map option, overrides the default method names on GithubUser. Because the model already has an id, updated_at, and created_at, we prefix the github api values with github. A prefix option is also available if all the defined methods shoudl be prefixed as well.

The validates line is not needed, but helps. Trying to access the attributes without a github_login set, will cause an error. And in this table, conceptually, it makes sense for one record per user, which is why we validate uniqueness as well.