Update field collection to allow inline fragment without type (#3384)

* init new defer example

* restructure example as flat, update gqlgen.yml

* update resolver to return data

* re-implement field collection for inline fragment to always test if the fragment type applies first
and that this test only happens if there is a fragment type defined

* remove superfluous field collection wrappers and simplify test format

* add tests; replicate logic for fragment spreads

* remove optional type fragment for spreads

* now that we've excised them from tests, re-introduce field collection helpers

* re-introduce collect all tests

* lint

* add back in context helpers to example

* make explanatory comments read easier and remove unnecessary changes

_examples/deferexample/gqlgen.yml

@@ -0,0 +1,26 @@
+schema: "*.graphql"
+
+exec:
+  filename: generated.go
+
+model:
+  filename: models_gen.go
+
+resolver:
+  layout: follow-schema
+  dir: .
+  filename_template: "{name}.resolvers.go"
+
+call_argument_directives_with_null: true
+
+models:
+  ID:
+    model:
+      - github.com/99designs/gqlgen/graphql.ID
+  Todo:
+    fields:
+      user:
+        resolver: true
+    extraFields:
+      userID:
+        type: "string"

_examples/deferexample/resolver.go

@@ -0,0 +1,8 @@
+package deferexample
+
+import "sync"
+
+type Resolver struct {
+	mu    sync.RWMutex
+	todos []*Todo
+}

_examples/deferexample/schema.graphql

@@ -0,0 +1,28 @@
+# GraphQL schema example
+#
+# https://gqlgen.com/getting-started/
+
+type Todo {
+  id: ID!
+  text: String!
+  done: Boolean!
+  user: User!
+}
+
+type User {
+  id: ID!
+  name: String!
+}
+
+type Query {
+  todos: [Todo!]!
+}
+
+input NewTodo {
+  text: String!
+  userId: String!
+}
+
+type Mutation {
+  createTodo(input: NewTodo!): Todo!
+}

_examples/deferexample/server/server.go

@@ -0,0 +1,59 @@
+package main
+
+import (
+	"log"
+	"net/http"
+	"os"
+	"time"
+
+	"github.com/99designs/gqlgen/_examples/deferexample"
+	"github.com/99designs/gqlgen/graphql/handler"
+	"github.com/99designs/gqlgen/graphql/handler/extension"
+	"github.com/99designs/gqlgen/graphql/handler/transport"
+	"github.com/99designs/gqlgen/graphql/playground"
+	"github.com/gorilla/websocket"
+	"github.com/rs/cors"
+)
+
+const defaultPort = "8080"
+
+func main() {
+	port := os.Getenv("PORT")
+	if port == "" {
+		port = defaultPort
+	}
+
+	c := cors.New(cors.Options{
+		AllowedOrigins:   []string{"*"},
+		AllowCredentials: true,
+		Debug:            false,
+	})
+
+	srv := handler.New(
+		deferexample.NewExecutableSchema(
+			deferexample.Config{Resolvers: &deferexample.Resolver{}},
+		),
+	)
+
+	srv.AddTransport(transport.SSE{})
+	srv.AddTransport(transport.MultipartMixed{
+		Boundary:        "graphql",
+		DeliveryTimeout: time.Millisecond * 10,
+	})
+	srv.AddTransport(transport.POST{})
+	srv.AddTransport(transport.Websocket{
+		KeepAlivePingInterval: 10 * time.Second,
+		Upgrader: websocket.Upgrader{
+			CheckOrigin: func(r *http.Request) bool {
+				return true
+			},
+		},
+	})
+	srv.Use(extension.Introspection{})
+
+	http.Handle("/", playground.Handler("Todo", "/query"))
+	http.Handle("/query", c.Handler(srv))
+
+	log.Printf("connect to http://localhost:%s/ for GraphQL playground", port)
+	log.Fatal(http.ListenAndServe(":"+port, nil))
+}

graphql/context_operation.go

@@ -77,7 +77,7 @@ func HasOperationContext(ctx context.Context) bool {
 	return ok && val != nil
 }
 
-// This is just a convenient wrapper method for CollectFields
+// CollectFieldsCtx is just a convenient wrapper method for CollectFields.
 func CollectFieldsCtx(ctx context.Context, satisfies []string) []CollectedField {
 	resctx := GetFieldContext(ctx)
 	return CollectFields(GetOperationContext(ctx), resctx.Field.Selections, satisfies)