Add tests and beginning functionality.

griffindy · Feb 23, 2015 · 77c55f9 · 77c55f9
1 parent b812a70
commit 77c55f9
Showing 5 changed files with 112 additions and 2 deletions.
diff --git a/lib/rackson.rb b/lib/rackson.rb
@@ -1,5 +1,19 @@
-require "rackson/version"
+require 'rackson/property'
+require 'rackson/version'
 
 module Rackson
-  # Your code goes here...
+  def self.included(base)
+    base.instance_variable_set(:@json_properties, [])
+    base.extend ClassMethods
+  end
+
+  module ClassMethods
+    def json_property(name, klass, options = {})
+      property = Rackson::Property.new(name, klass, options)
+      @json_properties << property
+      define_method(property.name) do
+        instance_variable_get("@#{property.name}")
+      end
+    end
+  end
 end
diff --git a/lib/rackson/object_mapper.rb b/lib/rackson/object_mapper.rb
@@ -0,0 +1,42 @@
+require 'json'
+
+module Rackson
+  class ObjectMapper
+    def deserialize(string, klass)
+      hash = JSON.parse(string)
+      deserialize_from_hash(hash, klass)
+    end
+
+    def deserialize_from_hash(hash, klass)
+      klass.new.tap do |instance|
+        klass.instance_variable_get(:@json_properties).each do |property|
+          value = generate_value property, hash
+          instance.instance_variable_set("@#{property.name}", value)
+        end
+      end
+    end
+
+    private
+
+    def generate_value(property, json_hash)
+      value_from_json = json_hash.fetch(property.name.to_s) do |key|
+        if property.required?
+          raise "missing required key #{key}"
+        end
+      end
+
+      case value_from_json
+      # already cast to the appropriate class
+      when property.klass
+        value_from_json
+      # needs to be deserialized into its own object
+      when Hash
+        deserialize_from_hash(value_from_json, property.klass)
+      when NilClass
+        nil
+      else
+        raise "type mismatch between #{value_from_json.inspect} (a #{value_from_json.class}) and #{property.klass}"
+      end
+    end
+  end
+end
diff --git a/lib/rackson/property.rb b/lib/rackson/property.rb
@@ -0,0 +1,15 @@
+module Rackson
+  class Property
+    attr_reader :name, :klass
+
+    def initialize(name, klass, options)
+      @name = name
+      @klass = klass
+      @options = options
+    end
+
+    def required?
+      !@options[:optional]
+    end
+  end
+end
diff --git a/rackson.gemspec b/rackson.gemspec
@@ -20,4 +20,5 @@ Gem::Specification.new do |spec|
 
   spec.add_development_dependency "bundler", "~> 1.7"
   spec.add_development_dependency "rake", "~> 10.0"
+  spec.add_development_dependency "rspec", "~> 3.0"
 end
diff --git a/spec/rackson/object_mapper_spec.rb b/spec/rackson/object_mapper_spec.rb
@@ -0,0 +1,38 @@
+require_relative '../../lib/rackson'
+require_relative '../../lib/rackson/object_mapper'
+
+describe Rackson::ObjectMapper do
+  let(:mapper) { Rackson::ObjectMapper.new }
+  class DifferentFakeObject
+    include Rackson
+    json_property :baz, String
+  end
+
+  class FakeObject
+    include Rackson
+    json_property :foo, String
+    json_property :bar, DifferentFakeObject
+    json_property :something_optional, String, optional: true
+  end
+
+  describe '#deserialize' do
+    let(:json_string) { '{"foo": "bar", "bar": {"baz":"another thing"}}' }
+    let(:deserialized) { mapper.deserialize(json_string, FakeObject) }
+
+    it 'returns an object of the given class' do
+      expect(deserialized).to be_a FakeObject
+    end
+
+    it 'sets the appropriate values' do
+      expect(deserialized.foo).to eq 'bar'
+    end
+
+    it 'understands non JSON POROs' do
+      expect(deserialized.bar.baz).to eq 'another thing'
+    end
+
+    it 'understands optional properties' do
+
+    end
+  end
+end