Merge pull request #30 from avvo/associations

Associations

Gemfile.lock

@@ -65,6 +65,3 @@ DEPENDENCIES
   rake
   simplecov
   webmock (> 0)
-
-BUNDLED WITH
-   1.11.2

lib/json_api_resource.rb

@@ -1,6 +1,8 @@
 require 'json_api_client'
 
 module JsonApiResource
+  autoload :Associatable,           'json_api_resource/associatable'
+  autoload :Associations,           'json_api_resource/associations'
   autoload :Cacheable,              'json_api_resource/cacheable'
   autoload :Clientable,             'json_api_resource/clientable'
   autoload :Connections,            'json_api_resource/connections'

lib/json_api_resource/associatable.rb

@@ -0,0 +1,60 @@
+module JsonApiResource
+  module Associatable
+    extend ActiveSupport::Concern
+
+    included do
+
+      class_attribute :_associations
+      self._associations = {}
+
+      attr_accessor :_cached_associations      
+
+      class << self
+        def belongs_to( name, opts = {} )
+          process Associations::BelongsTo.new( self, name, opts )
+        end
+
+        def has_one( name, opts = {} )
+          process Associations::HasOne.new( self, name, opts )
+        end
+
+        def has_many( name, opts = {} )
+          if opts[:prefetched_ids]
+            process Associations::HasManyPrefetched.new( self, name, opts )
+          else
+            process Associations::HasMany.new( self, name, opts )
+          end
+        end
+
+        private
+
+        def process(association)
+          add_association association
+          methodize association
+        end
+
+        def add_association(association)
+          self._associations = _associations.merge association.name => association
+        end
+
+        def methodize( association )
+          define_method association.name do 
+            self._cached_associations ||= {}
+            unless self._cached_associations.has_key? association.name
+              if association.callable?(self)
+                result = association.klass.send( association.action, association.query(self) )
+                result = association.post_process result
+              else
+                result = association.nil_default
+              end
+
+              self._cached_associations[association.name] = result
+            end
+            self._cached_associations[association.name]
+          end
+        end
+      end
+    end
+  end
+end
+

lib/json_api_resource/associations.rb

@@ -0,0 +1,17 @@
+module JsonApiResource
+  module Associations
+    autoload :Base,               'json_api_resource/associations/base'
+    autoload :BelongsTo,          'json_api_resource/associations/belongs_to'
+    autoload :HasManyPrefetched,  'json_api_resource/associations/has_many_prefetched'
+    autoload :HasOne,             'json_api_resource/associations/has_one'
+    autoload :HasMany,            'json_api_resource/associations/has_many'
+    autoload :Preloader,          'json_api_resource/associations/preloader'
+    autoload :Preloaders,         'json_api_resource/associations/preloaders'
+
+
+    BELONGS_TO          = :belongs_to
+    HAS_ONE             = :has_one
+    HAS_MANY            = :has_many
+    HAS_MANY_PREFETCHED = :has_many_prefetched
+  end
+end

lib/json_api_resource/associations/base.rb

@@ -0,0 +1,79 @@
+module JsonApiResource
+  module Associations
+    class Base
+      include ::JsonApiResource::Errors
+      attr_accessor :name, :action, :key, :root
+
+      def initialize(associated_class, name, opts = {})
+        self.name   = name.to_sym
+        self.root   = associated_class
+        @opts       = opts.merge( skip_pagination: true )
+
+        self.action = @opts.delete :action       do default_action end
+        self.key    = @opts.delete :foreign_key  do server_key end
+
+        self.key    = self.key.try :to_sym
+        validate_options
+      end
+
+      def type
+        raise NotImplementedError
+      end
+
+      def query( root_insatnce )
+        raise NotImplementedError
+      end
+
+      def callable?( root_insatnce )
+        raise NotImplementedError
+      end
+
+      def default_nil
+        raise NotImplementedError
+      end
+
+      # klass has to be lazy initted for circular dependencies
+      def klass
+        @klass ||= @opts.delete :class do derived_class end
+      end
+
+      def post_process( value )
+        value
+      end
+
+      def opts
+        @opts.except *ASSOCIATION_OPTS
+      end
+
+      protected
+
+      def server_key
+        raise NotImplementedError
+      end
+
+      def default_action
+        raise NotImplementedError
+      end
+
+      def derived_class
+        module_string = self.root.to_s.split("::")[0 ... -1].join("::")
+        class_string  = name.to_s.singularize.camelize
+
+        # we don't necessarily want to add :: to classes, in case they have a relative path or something
+        class_string = [module_string, class_string].select{|s| s.present? }.join "::"
+        class_string.constantize
+      end
+
+      ASSOCIATION_OPTS  = [:class, :action, :foreign_key, :prefetched_ids]
+
+      RESERVED_KEYWORDS = [:attributes, :_associations, :_cached_associations, :schema, :client]
+
+      def validate_options
+        raise_unless action.present?, "Invalid action: #{self.root}.#{name}"
+        raise_unless    key.present?, "Invalid foreign_key for #{self.root}.#{name}"
+
+        raise_if RESERVED_KEYWORDS.include?(name), "'#{name}' is a reserved keyword for #{self.root}"
+      end
+    end
+  end
+end

lib/json_api_resource/associations/belongs_to.rb

@@ -0,0 +1,29 @@
+module JsonApiResource
+  module Associations
+    class BelongsTo < Base
+      def default_action
+        :find
+      end
+
+      def server_key
+        "#{name}_id"
+      end
+
+      def query( root_instance )
+        root_instance.send key
+      end
+
+      def callable?( root_instance )
+        root_instance.send(key).present?
+      end
+
+      def nil_default
+        nil
+      end
+
+      def type
+        JsonApiResource::Associations::BELONGS_TO
+      end
+    end
+  end
+end

lib/json_api_resource/associations/has_many.rb

@@ -0,0 +1,26 @@
+module JsonApiResource
+  module Associations
+    class HasMany < Base
+      def default_action
+        :where
+      end
+
+      def server_key
+        class_name = self.root.to_s.demodulize.underscore
+        "#{class_name}_id"
+      end
+
+      def callable?( root_instance )
+        true
+      end
+
+      def query( root_instance )
+        { key => root_instance.id }.merge(opts)
+      end
+
+      def type
+        JsonApiResource::Associations::HAS_MANY
+      end
+    end
+  end
+end

lib/json_api_resource/associations/has_many_prefetched.rb

@@ -0,0 +1,34 @@
+module JsonApiResource
+  module Associations
+    class HasManyPrefetched < Base
+      def default_action
+        :where
+      end
+
+      def server_key
+        @opts[:prefetched_ids]
+      end
+
+      def query( root_instance )
+        { id: root_instance.send(key) }.merge(opts)
+      end
+
+      def callable?( root_instance )
+        root_instance.send(key).present?
+      end
+
+      def nil_default
+        []
+      end
+
+      def type
+        JsonApiResource::Associations::HAS_MANY_PREFETCHED
+      end
+
+      def validate_options
+        raise_unless key == server_key, "#{root}.#{name} cannot specify both prefetched_ids and a foreign key"
+        super
+      end
+    end
+  end
+end

lib/json_api_resource/associations/has_one.rb

@@ -0,0 +1,30 @@
+module JsonApiResource
+  module Associations
+    class HasOne < Base
+      def post_process( value )
+        Array(value).first
+      end
+
+      def default_action  
+        :where
+      end
+
+      def server_key
+        class_name = self.root.to_s.demodulize.underscore
+        "#{class_name}_id"
+      end
+
+      def query( root_instance )
+        { key => root_instance.id }.merge(opts)
+      end
+
+      def callable?( root_instance )
+        true
+      end
+
+      def type
+        JsonApiResource::Associations::HAS_ONE
+      end
+    end
+  end
+end

lib/json_api_resource/associations/preloader.rb

@@ -0,0 +1,58 @@
+module JsonApiResource
+  module Associations
+    class Preloader
+      include JsonApiResource::Errors
+
+      class << self
+        def preload ( objects, preloads )
+          objects  = Array(objects)
+          preloads = Array(preloads)
+
+          preloads.each do |preload|
+
+            association = association_for objects, preload
+
+            preloader   = preloader_for association
+
+            preloader.preload( objects )
+
+          end
+        end
+
+        private
+
+        def association_for( objects, preload )
+          # let's assert the objects are of a single class
+          verify_object_homogenity!(objects)
+
+          obj_class   = objects.first.class
+          association = obj_class._associations[preload]
+
+          raise_if association.nil?, "'#{preload}' is not a valid association on #{obj_class}"
+
+          association
+        end
+
+        def preloader_for( association )
+          preloader_class = PREOLOADERS_FOR_ASSOCIATIONS[association.type]
+          preloader_class.new association
+        end
+
+        def verify_object_homogenity!( objects )
+          obj_class = objects.first.class
+
+          objects.each do |obj|
+            raise_unless obj.is_a?(obj_class), "JsonApiResource::Associations::Preloader.preload called with a heterogenious array of objects."
+          end
+        end
+
+        PREOLOADERS_FOR_ASSOCIATIONS = {
+                                          JsonApiResource::Associations::BELONGS_TO          => JsonApiResource::Associations::Preloaders::BelongsToPreloader,
+                                          JsonApiResource::Associations::HAS_ONE             => JsonApiResource::Associations::Preloaders::HasOnePreloader,
+                                          JsonApiResource::Associations::HAS_MANY            => JsonApiResource::Associations::Preloaders::HasManyPreloader,
+                                          JsonApiResource::Associations::HAS_MANY_PREFETCHED => JsonApiResource::Associations::Preloaders::HasManyPrefetchedPreloader,
+                                        }
+      end
+    end
+  end
+end

lib/json_api_resource/associations/preloaders.rb

@@ -0,0 +1,12 @@
+module JsonApiResource
+  module Associations
+    module Preloaders
+      autoload :Base,                         'json_api_resource/associations/preloaders/base'
+      autoload :BelongsToPreloader,           'json_api_resource/associations/preloaders/belongs_to_preloader'
+      autoload :Distributors,                 'json_api_resource/associations/preloaders/distributors'
+      autoload :HasManyPrefetchedPreloader,   'json_api_resource/associations/preloaders/has_many_prefetched_preloader'
+      autoload :HasManyPreloader,             'json_api_resource/associations/preloaders/has_many_preloader'
+      autoload :HasOnePreloader,              'json_api_resource/associations/preloaders/has_one_preloader'
+    end
+  end
+end