Merge pull request #233 from caws/raise-errors-for-invalid-blueprints

Raise errors for invalid blueprints for associations

lib/blueprinter/base.rb

@@ -156,7 +156,7 @@ def self.field(method, options = {}, &block)
     #
     # @return [Field] A Field object
     def self.association(method, options = {}, &block)
-      raise BlueprinterError, 'blueprint required' unless options[:blueprint]
+      validate_blueprint!(options[:blueprint], method)
 
       field(
         method,
@@ -214,7 +214,7 @@ def self.render(object, options = {})
     #   # => [{id:1, title: Hello},{id:2, title: My Day}]
     #
     # @return [Hash]
-    def self.render_as_hash(object, options= {})
+    def self.render_as_hash(object, options = {})
       prepare_for_render(object, options)
     end
 
@@ -239,7 +239,7 @@ def self.render_as_hash(object, options= {})
     #   # => [{"id" => "1", "title" => "Hello"},{"id" => "2", "title" => "My Day"}]
     #
     # @return [Hash]
-    def self.render_as_json(object, options= {})
+    def self.render_as_json(object, options = {})
       prepare_for_render(object, options).as_json
     end
 
@@ -279,7 +279,6 @@ def self.fields(*field_names)
     end
 
 
-
     # Specify one transformer to be included for serialization.
     # Takes a class which extends Blueprinter::Transformer
     #

lib/blueprinter/helpers/base_helpers.rb

@@ -8,31 +8,32 @@ module SingletonMethods
       include TypeHelpers
 
       private
+
       def prepare_for_render(object, options)
         view_name = options.delete(:view) || :default
         root = options.delete(:root)
         meta = options.delete(:meta)
-        validate_root_and_meta(root, meta)
+        validate_root_and_meta!(root, meta)
         prepare(object, view_name: view_name, local_options: options, root: root, meta: meta)
       end
 
       def prepare_data(object, view_name, local_options)
         if array_like?(object)
           object.map do |obj|
             object_to_hash(obj,
-                          view_name: view_name,
-                          local_options: local_options)
+                           view_name: view_name,
+                           local_options: local_options)
           end
         else
           object_to_hash(object,
-                        view_name: view_name,
-                        local_options: local_options)
+                         view_name: view_name,
+                         local_options: local_options)
         end
       end
 
       def prepend_root_and_meta(data, root, meta)
         return data unless root
-        ret = { root => data }
+        ret = {root => data}
         meta ? ret.merge!(meta: meta) : ret
       end
 
@@ -43,15 +44,15 @@ def inherited(subclass)
       def object_to_hash(object, view_name:, local_options:)
         result_hash = view_collection.fields_for(view_name).each_with_object({}) do |field, hash|
           next if field.skip?(field.name, object, local_options)
-           hash[field.name] = field.extract(object, local_options)
+          hash[field.name] = field.extract(object, local_options)
         end
         view_collection.transformers(view_name).each do |transformer|
-           transformer.transform(result_hash,object,local_options)
+          transformer.transform(result_hash, object, local_options)
         end
         result_hash
       end
 
-      def validate_root_and_meta(root, meta)
+      def validate_root_and_meta!(root, meta)
         case root
         when String, Symbol
           # no-op
@@ -62,6 +63,44 @@ def validate_root_and_meta(root, meta)
         end
       end
 
+      def dynamic_blueprint?(blueprint)
+        blueprint.is_a?(Proc)
+      end
+
+      def validate_blueprint!(blueprint, method)
+        validate_presence_of_blueprint!(blueprint)
+        unless dynamic_blueprint?(blueprint)
+          validate_blueprint_has_ancestors!(blueprint, method)
+          validate_blueprint_has_blueprinter_base_ancestor!(blueprint, method)
+        end
+      end
+
+      def validate_presence_of_blueprint!(blueprint)
+        raise BlueprinterError, 'Blueprint required' unless blueprint
+      end
+
+      def validate_blueprint_has_ancestors!(blueprint, association_name)
+        # If the class passed as a blueprint does not respond to ancestors
+        # it means it, at the very least, does not have Blueprinter::Base as
+        # one of its ancestor classes (e.g: Hash) and thus an error should
+        # be raised.
+        unless blueprint.respond_to?(:ancestors)
+          raise BlueprinterError, "Blueprint provided for #{association_name} "\
+                                'association is not valid.'
+        end
+      end
+
+      def validate_blueprint_has_blueprinter_base_ancestor!(blueprint, association_name)
+        # Guard clause in case Blueprinter::Base is present in the ancestor list
+        # for the blueprint class provided.
+        return if blueprint.ancestors.include? Blueprinter::Base
+
+        # Raise error describing what's wrong.
+        raise BlueprinterError, "Class #{blueprint.name} does not inherit from "\
+                              'Blueprinter::Base and is not a valid Blueprinter '\
+                              "for #{association_name} association."
+      end
+
       def jsonify(blob)
         Blueprinter.configuration.jsonify(blob)
       end

spec/integrations/base_spec.rb

@@ -87,6 +87,26 @@
           end
           it('returns json with association') { should eq(result) }
         end
+        context 'Given associated blueprint does not inherit from Blueprinter::Base' do
+          let(:blueprint) do
+            vehicle_invalid_blueprint = Class.new
+            Class.new(Blueprinter::Base) do
+              identifier :id
+              association :vehicles, blueprint: vehicle_invalid_blueprint
+            end
+          end
+          it { expect { subject }.to raise_error(Blueprinter::BlueprinterError) }
+        end
+        context 'Given associated blueprint does not have any ancestors' do
+          let(:blueprint) do
+            vehicle_invalid_blueprint = {}
+            Class.new(Blueprinter::Base) do
+              identifier :id
+              association :vehicles, blueprint: vehicle_invalid_blueprint
+            end
+          end
+          it { expect { subject }.to raise_error(Blueprinter::BlueprinterError) }
+        end
         context "Given association with dynamic blueprint" do
           class UserBlueprint < Blueprinter::Base
             fields :id