Merge pull request #344 from cerebris/abstract

Adds abstract option

Author: dgeb

README.md

@@ -54,6 +54,25 @@ class ContactResource < JSONAPI::Resource
 end
 ```
 
+##### Abstract Resources
+
+Resources that are not backed by a model (purely used as base classes for other resources) should be declared as 
+abstract.
+
+Because abstract resources do not expect to be backed by a model, they won't attempt to discover the model class
+or any of its relationships.
+
+```ruby
+class BaseResource < JSONAPI::Resource
+  abstract
+  
+  has_one :creator
+end
+
+class ContactResource < BaseResource
+end
+```
+
 #### Attributes
 
 Any of a resource's attributes that are accessible must be explicitly declared. Single attributes can be declared using

lib/jsonapi/resource.rb

@@ -257,6 +257,7 @@ def _replace_fields(field_data)
 
     class << self
       def inherited(base)
+        base.abstract(false)
         base._attributes = (_attributes || {}).dup
         base._relationships = (_relationships || {}).dup
         base._allowed_filters = (_allowed_filters || Set.new).dup
@@ -620,10 +621,20 @@ def paginator(paginator)
         @_paginator = paginator
       end
 
+      def abstract(val = true)
+        @abstract = val
+      end
+
+      def _abstract
+        @abstract
+      end
+
       def _model_class
+        return nil if _abstract
+
         return @model if @model
         @model = _model_name.to_s.safe_constantize
-        fail NameError, "model could not be found for #{self.name}" if @model.nil?
+        warn "[MODEL NOT FOUND] Model could not be found for #{self.name}. If this a base Resource declare it as abstract." if @model.nil?
         @model
       end
 
@@ -675,7 +686,7 @@ def _add_relationship(klass, *attrs)
           check_reserved_relationship_name(attr)
 
           # Initialize from an ActiveRecord model's properties
-          if _model_class < ActiveRecord::Base
+          if _model_class && _model_class < ActiveRecord::Base
             model_association = _model_class.reflect_on_association(attr)
             if model_association
               options[:class_name] ||= model_association.class_name

test/fixtures/active_record.rb

@@ -648,7 +648,11 @@ class NumerosTelefoneController < JSONAPI::ResourceController
 end
 
 ### RESOURCES
-class PersonResource < JSONAPI::Resource
+class BaseResource < JSONAPI::Resource
+  abstract
+end
+
+class PersonResource < BaseResource
   attributes :id, :name, :email
   attribute :date_joined, format: :date_with_timezone
 

test/unit/resource/resource_test.rb

@@ -11,6 +11,10 @@ def self.records(options)
 class NoMatchResource < JSONAPI::Resource
 end
 
+class NoMatchAbstractResource < JSONAPI::Resource
+  abstract
+end
+
 class CatResource < JSONAPI::Resource
   attribute :id
   attribute :name
@@ -55,12 +59,25 @@ def test_model
     assert_equal(PostResource._model_class, Post)
   end
 
+  def test_base_resource_abstract
+    assert BaseResource._abstract
+  end
+
+  def test_derived_not_abstract
+    assert PersonResource < BaseResource
+    refute PersonResource._abstract
+  end
+
   def test_nil_model_class
-    error = assert_raises(NameError) { NoMatchResource._model_class }
-    assert_equal(
-      error.message,
-      "model could not be found for NoMatchResource"
-    )
+    assert_output nil, "[MODEL NOT FOUND] Model could not be found for NoMatchResource. If this a base Resource declare it as abstract.\n" do
+      assert_nil NoMatchResource._model_class
+    end
+  end
+
+  def test_nil_abstract_model_class
+    assert_output nil, '' do
+      assert_nil NoMatchAbstractResource._model_class
+    end
   end
 
   def test_model_alternate