From 480ea5ae37cb27538e909a4844240258525fb096 Mon Sep 17 00:00:00 2001
From: Derek Lindahl <dlindahl@customink.com>
Date: Mon, 6 Apr 2015 15:41:55 -0700
Subject: [PATCH] Add alternate string identifier support for Resource.find

This allows the usage of non-Fixnum unique identifiers for GETs for a
specific resource as long as a matching _link is defined in the Api
Schema.
---
 lib/frenetic.rb                               |  1 +
 lib/frenetic/behaviors.rb                     |  6 ++
 .../behaviors/alternate_string_identifier.rb  | 55 +++++++++++++++++++
 .../alternate_string_identifier_spec.rb       | 44 +++++++++++++++
 4 files changed, 106 insertions(+)
 create mode 100644 lib/frenetic/behaviors.rb
 create mode 100644 lib/frenetic/behaviors/alternate_string_identifier.rb
 create mode 100644 spec/behaviors/alternate_string_identifier_spec.rb

diff --git a/lib/frenetic.rb b/lib/frenetic.rb
index ac01761..30ae3c8 100644
--- a/lib/frenetic.rb
+++ b/lib/frenetic.rb
@@ -6,6 +6,7 @@
 
 require 'frenetic/version'
 require 'frenetic/errors'
+require 'frenetic/behaviors'
 require 'frenetic/briefly_memoizable'
 require 'frenetic/connection'
 require 'frenetic/middleware/hal_json'
diff --git a/lib/frenetic/behaviors.rb b/lib/frenetic/behaviors.rb
new file mode 100644
index 0000000..2440745
--- /dev/null
+++ b/lib/frenetic/behaviors.rb
@@ -0,0 +1,6 @@
+require 'frenetic/behaviors/alternate_string_identifier'
+
+class Frenetic
+  module Behaviors
+  end
+end
diff --git a/lib/frenetic/behaviors/alternate_string_identifier.rb b/lib/frenetic/behaviors/alternate_string_identifier.rb
new file mode 100644
index 0000000..dbf5da1
--- /dev/null
+++ b/lib/frenetic/behaviors/alternate_string_identifier.rb
@@ -0,0 +1,55 @@
+# Allows a resource to be found by a string-based alternative key
+#
+# For example
+#
+# module MyClient
+#   module MyResource < Frenetic::Resource
+#     extend Frenetic::Behaviors::AlternateStringIdentifier
+#
+#     def self.find(id)
+#       super(finder_params(id, :username))
+#     end
+#   end
+# end
+#
+# Given an Api Schema such as:
+#
+# {
+#   _links: {
+#     my_resource: [{
+#       { href: '/api/my_resource/{id}', rel: 'id' },
+#       { href: '/api/my_resource/{username}?specific_to=username', rel: 'username' },
+#     }]
+#   }
+# }
+#
+# MyClient::MyResource.find will choose the alternate link relation based on
+# the string-based ID passed in.
+#
+# MyClient::MyResource.find(1)
+# # Executes /api/my_resource/1
+#
+# MyClient::MyResource.find('100')
+# # Executes /api/my_resource/100
+#
+# MyClient::MyResource.find('jdoe')
+# Executes /api/my_resource/jdoe?specific_to=username
+#
+class Frenetic
+  module Behaviors
+    module AlternateStringIdentifier
+      def finder_params(unique_id, alternate_key)
+        return unique_id if unique_id.is_a? Hash
+        params = {}
+        key = nil
+        if unique_id.to_i.to_s == unique_id.to_s
+          key = :id
+        elsif !unique_id.nil?
+          key = alternate_key
+        end
+        params[key] = unique_id
+        params
+      end
+    end
+  end
+end
diff --git a/spec/behaviors/alternate_string_identifier_spec.rb b/spec/behaviors/alternate_string_identifier_spec.rb
new file mode 100644
index 0000000..15708da
--- /dev/null
+++ b/spec/behaviors/alternate_string_identifier_spec.rb
@@ -0,0 +1,44 @@
+require 'spec_helper'
+
+describe Frenetic::Behaviors::AlternateStringIdentifier do
+  let(:my_temp_resource) do
+    Class.new(Frenetic::Resource)
+  end
+
+  before do
+    stub_const 'MyTempResource', my_temp_resource
+    MyTempResource.send(:extend, described_class)
+  end
+
+  describe '.finder_params' do
+    let(:id) { }
+    let(:alternate_key) { }
+
+    subject { MyTempResource.finder_params(id, alternate_key) }
+
+    context 'with a Fixnum identifier' do
+      let(:id) { 1 }
+
+      it 'uses :id for the finder key' do
+        expect(subject).to include id:id
+      end
+    end
+
+    context 'with a String identifier representing a Fixnum' do
+      let(:id) { '100' }
+
+      it 'uses :id for the finder key' do
+        expect(subject).to include id:id
+      end
+    end
+
+    context 'with a String identifier' do
+      let(:id) { 'foo' }
+      let(:alternate_key) { 'alt' }
+
+      it 'uses :id for the finder key' do
+        expect(subject).to include 'alt' => id
+      end
+    end
+  end
+end