Raise helpful error if missing serializer (#100)

Author: richmolj

lib/jsonapi_compliable/errors.rb

@@ -3,6 +3,23 @@ module Errors
     class BadFilter < StandardError; end
     class ValidationError < StandardError; end
 
+    class MissingSerializer < StandardError
+      def initialize(class_name, serializer_name)
+        @class_name = class_name
+        @serializer_name = serializer_name
+      end
+
+      def message
+        <<-MSG
+Could not find serializer for class '#{@class_name}'!
+
+Looked for '#{@serializer_name}' but doesn't appear to exist.
+
+Use a custom Inferrer if you'd like different lookup logic.
+        MSG
+      end
+    end
+
     class UnsupportedPageSize < StandardError
       def initialize(size, max)
         @size, @max = size, max

lib/jsonapi_compliable/util/render_options.rb

@@ -6,12 +6,6 @@ class RenderOptions
       def self.generate(object, query_hash, overrides = {})
         resolved = object.respond_to?(:resolve) ? object.resolve : object
 
-        inferrer = ::Hash.new do |h, k|
-          names = k.to_s.split('::')
-          klass = names.pop
-          h[k] = [*names, "Serializable#{klass}"].join('::').safe_constantize
-        end
-
         fields = query_hash[:fields].dup
         extra_fields = query_hash[:extra_fields]
 
@@ -37,6 +31,21 @@ def self.generate(object, query_hash, overrides = {})
 
         options
       end
+
+      def self.inferrer
+        ::Hash.new do |h, k|
+          names = k.to_s.split('::')
+          klass = names.pop
+          serializer_name = [*names, "Serializable#{klass}"].join('::')
+          serializer = serializer_name.safe_constantize
+          if serializer
+            h[k] = serializer
+          else
+            raise Errors::MissingSerializer.new(k, serializer_name)
+          end
+        end
+      end
+      private_class_method :inferrer
     end
   end
 end

spec/integration/rails/finders_spec.rb

@@ -235,6 +235,18 @@ def json
       end
     end
 
+    context 'when no serializer is found' do
+      before do
+        allow_any_instance_of(String).to receive(:safe_constantize) { nil }
+      end
+
+      it 'raises helpful error' do
+        expect {
+          get :index
+        }.to raise_error(JsonapiCompliable::Errors::MissingSerializer)
+      end
+    end
+
     context 'sideloading has_many' do
       # TODO: may want to blow up here, only for index action
       it 'allows pagination of sideloaded resource' do