Add support for inline and named fragments

lib/graphql/query_resolver.rb

@@ -3,75 +3,92 @@
 
 module GraphQL
   module QueryResolver
+    def self.run(model_class, context, _return_type, &block)
+      Resolver.new(model_class, context).call(&block)
+    end
 
-    def self.run(model_class, context, return_type)
-      to_load = yield
-      dependencies = {}
-
-      reflection_dependencies = map_dependencies(model_class, context.ast_node)
-      dependencies = reflection_dependencies.merge(dependencies)
+    class Resolver
+      attr_reader :context, :fragment_definitions
 
-      if dependencies.any? && to_load.present?
-        if ActiveRecord::VERSION::MAJOR < 4
-          ActiveRecord::Associations::Preloader.new(to_load, dependencies).run
-        else
-          ActiveRecord::Associations::Preloader.new.preload(to_load, dependencies)
-        end
+      def initialize(model_class, context)
+        @model_class = model_class
+        @context = context
+        @fragment_definitions = context.query.fragments
       end
 
-      to_load
-    end
+      def call
+        to_load = yield
+        dependencies = map_dependencies(@model_class, context.ast_node)
 
-    def self.using_relay_pagination?(selection)
-      selection.name == 'edges'
-    end
+        if dependencies.any? && to_load.present?
+          preload_dependencies(to_load, dependencies)
+        end
 
-    def self.using_nodes_pagination?(selection)
-      selection.name == 'nodes'
-    end
+        to_load
+      end
 
-    def self.map_relay_pagination_depencies(class_name, selection, dependencies)
-      node_selection = selection.selections.find { |sel| sel.name == 'node' }
+      private
 
-      if node_selection.present?
-        map_dependencies(class_name, node_selection, dependencies)
-      else
-        dependencies
-      end
-    end
+      def preload_dependencies(to_load, dependencies)
+        if ActiveRecord::VERSION::MAJOR < 4
+          return ActiveRecord::Associations::Preloader.new(
+            to_load, dependencies
+          ).run
+        end
 
-    def self.has_reflection_with_name?(class_name, selection_name)
-      class_name.reflections.with_indifferent_access[selection_name].present?
-    end
+        ActiveRecord::Associations::Preloader.new.preload(to_load, dependencies)
+      end
 
-    def self.map_dependencies(class_name, ast_node, dependencies={})
-      ast_node.selections.each do |selection|
-        name = selection.name
+      def map_dependencies(class_name, ast_node, dependencies = {})
+        ast_node.selections.each do |selection|
+          if inline_fragment?(selection) || relay_connection_using_nodes?(selection)
+            dig_deeper = selection
+          elsif fragment_spread?(selection)
+            dig_deeper = fragment_definitions[selection.name]
+          elsif relay_connection_using_edges?(selection)
+            dig_deeper = selection.selections.find { |sel| sel.name == 'node' }
+          end
 
-        if using_relay_pagination?(selection)
-          map_relay_pagination_depencies(class_name, selection, dependencies)
-          next
-        end
+          if dig_deeper.present?
+            map_dependencies(class_name, dig_deeper, dependencies)
+            next
+          end
 
-        if using_nodes_pagination?(selection)
-          map_dependencies(class_name, selection, dependencies)
-          next
-        end
+          name = selection.name
+          next unless preloadable_reflection?(class_name, name)
 
-        if has_reflection_with_name?(class_name, name)
           begin
-            current_class_name = selection.name.singularize.classify.constantize
-            dependencies[name] = map_dependencies(current_class_name, selection)
+            next_model_class = name.singularize.classify.constantize
           rescue NameError
-            selection_name = class_name.reflections.with_indifferent_access[selection.name].options[:class_name]
-            current_class_name = selection_name.singularize.classify.constantize
-            dependencies[selection.name.to_sym] = map_dependencies(current_class_name, selection)
-            next
+            selection_name = class_name.reflections[name].options[:class_name]
+            next_model_class = selection_name.singularize.classify.constantize
           end
+
+          dependencies[name.to_sym] = map_dependencies(next_model_class, selection)
         end
+
+        dependencies
       end
 
-      dependencies
+      def preloadable_reflection?(class_name, selection_name)
+        class_name.reflections.with_indifferent_access[selection_name].present?
+      end
+
+      def relay_connection_using_edges?(selection)
+        selection.name == 'edges'
+      end
+
+      def relay_connection_using_nodes?(selection)
+        selection.name == 'nodes'
+      end
+
+      def inline_fragment?(selection)
+        selection.is_a?(GraphQL::Language::Nodes::InlineFragment)
+      end
+
+      def fragment_spread?(selection)
+        selection.is_a?(GraphQL::Language::Nodes::FragmentSpread)
+      end
     end
   end
 end

spec/graphql/query_resolver_spec.rb

@@ -81,6 +81,44 @@
     expect(queries[4]).to include('SELECT "vendors".* FROM "vendors" WHERE "vendors"."id" IN (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11)')
   end
 
+  it 'works with inline and spread fragments' do
+    data = nil
+
+    queries = track_queries do
+      data = GQL.query(%{
+        fragment ChefFragment on chef {
+          name
+          recipes {
+            title
+            ingredients {
+              name, quantity
+              vendor {
+                name
+              }
+            }
+          }
+        }
+
+        query {
+          restaurant(id: 1) {
+            ... on restaurant {
+              name
+              owner {
+                ... ChefFragment
+              }
+            }
+          }
+        }
+      })
+    end
+
+    expect(queries[0]).to include('SELECT "restaurants".* FROM "restaurants" WHERE "restaurants"."id" = ?')
+    expect(queries[1]).to include('SELECT "chefs".* FROM "chefs" WHERE "chefs"."id"') # AR 4 will use id IN (1), AR 5 will use id = 1
+    expect(queries[2]).to include('SELECT "recipes".* FROM "recipes" WHERE "recipes"."chef_id"') # AR 4 will use id IN (1), AR 5 will use id = 1
+    expect(queries[3]).to include('SELECT "ingredients".* FROM "ingredients" WHERE "ingredients"."recipe_id" IN (1, 2, 3, 4)')
+    expect(queries[4]).to include('SELECT "vendors".* FROM "vendors" WHERE "vendors"."id" IN (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11)')
+  end
+
   it 'works with alias reflections' do
     # Owner is an instance of Chef
     query = %{
@@ -152,4 +190,34 @@
 
     expect(queries.size).to eq(2)
   end
+
+  it 'mixing "nodes" and fragments' do
+    query = %{
+      query {
+        vendors(first: 5) {
+          nodes {
+            ... on vendor {
+              id
+              name
+              ingredients {
+                ... on ingredient {
+                  name
+                  quantity
+                }
+              }
+            }
+          }
+          pageInfo {
+            endCursor
+            hasNextPage
+          }
+        }
+      }
+    }
+    queries = track_queries do
+      GQL.query(query)
+    end
+
+    expect(queries.size).to eq(2)
+  end
 end