example/starwars: change Episode enum implementation to int type

example/starwars/starwars.go

@@ -143,11 +143,47 @@ var Schema = `
 	union SearchResult = Human | Droid | Starship
 `
 
+type episode int
+
+const (
+	newHopeEpisode episode = iota
+	empireEpisode
+	jediEpisode
+)
+
+var nameToEp = map[string]episode{
+	"NEWHOPE": newHopeEpisode,
+	"EMPIRE":  empireEpisode,
+	"JEDI":    jediEpisode,
+}
+
+var epToName = map[episode]string{
+	newHopeEpisode: "NEWHOPE",
+	empireEpisode:  "EMPIRE",
+	jediEpisode:    "JEDI",
+}
+
+func (e episode) String() string {
+	return epToName[e]
+}
+
+func (episode) ImplementsGraphQLType(name string) bool {
+	return name == "Episode"
+}
+
+func (e *episode) UnmarshalGraphQL(input interface{}) error {
+	if str, ok := input.(string); ok {
+		*e = nameToEp[str]
+		return nil
+	}
+	return fmt.Errorf("wrong type for Episode: %T", input)
+}
+
 type human struct {
 	ID        graphql.ID
 	Name      string
 	Friends   []graphql.ID
-	AppearsIn []string
+	AppearsIn []episode
 	Height    float64
 	Mass      int
 	Starships []graphql.ID
@@ -158,7 +194,7 @@ var humans = []*human{
 		ID:        "1000",
 		Name:      "Luke Skywalker",
 		Friends:   []graphql.ID{"1002", "1003", "2000", "2001"},
-		AppearsIn: []string{"NEWHOPE", "EMPIRE", "JEDI"},
+		AppearsIn: []episode{newHopeEpisode, empireEpisode, jediEpisode},
 		Height:    1.72,
 		Mass:      77,
 		Starships: []graphql.ID{"3001", "3003"},
@@ -167,7 +203,7 @@ var humans = []*human{
 		ID:        "1001",
 		Name:      "Darth Vader",
 		Friends:   []graphql.ID{"1004"},
-		AppearsIn: []string{"NEWHOPE", "EMPIRE", "JEDI"},
+		AppearsIn: []episode{newHopeEpisode, empireEpisode, jediEpisode},
 		Height:    2.02,
 		Mass:      136,
 		Starships: []graphql.ID{"3002"},
@@ -176,7 +212,7 @@ var humans = []*human{
 		ID:        "1002",
 		Name:      "Han Solo",
 		Friends:   []graphql.ID{"1000", "1003", "2001"},
-		AppearsIn: []string{"NEWHOPE", "EMPIRE", "JEDI"},
+		AppearsIn: []episode{newHopeEpisode, empireEpisode, jediEpisode},
 		Height:    1.8,
 		Mass:      80,
 		Starships: []graphql.ID{"3000", "3003"},
@@ -185,15 +221,15 @@ var humans = []*human{
 		ID:        "1003",
 		Name:      "Leia Organa",
 		Friends:   []graphql.ID{"1000", "1002", "2000", "2001"},
-		AppearsIn: []string{"NEWHOPE", "EMPIRE", "JEDI"},
+		AppearsIn: []episode{newHopeEpisode, empireEpisode, jediEpisode},
 		Height:    1.5,
 		Mass:      49,
 	},
 	{
 		ID:        "1004",
 		Name:      "Wilhuff Tarkin",
 		Friends:   []graphql.ID{"1001"},
-		AppearsIn: []string{"NEWHOPE"},
+		AppearsIn: []episode{newHopeEpisode},
 		Height:    1.8,
 		Mass:      0,
 	},
@@ -211,7 +247,7 @@ type droid struct {
 	ID              graphql.ID
 	Name            string
 	Friends         []graphql.ID
-	AppearsIn       []string
+	AppearsIn       []episode
 	PrimaryFunction string
 }
 
@@ -220,14 +256,14 @@ var droids = []*droid{
 		ID:              "2000",
 		Name:            "C-3PO",
 		Friends:         []graphql.ID{"1000", "1002", "1003", "2001"},
-		AppearsIn:       []string{"NEWHOPE", "EMPIRE", "JEDI"},
+		AppearsIn:       []episode{newHopeEpisode, empireEpisode, jediEpisode},
 		PrimaryFunction: "Protocol",
 	},
 	{
 		ID:              "2001",
 		Name:            "R2-D2",
 		Friends:         []graphql.ID{"1000", "1002", "1003"},
-		AppearsIn:       []string{"NEWHOPE", "EMPIRE", "JEDI"},
+		AppearsIn:       []episode{newHopeEpisode, empireEpisode, jediEpisode},
 		PrimaryFunction: "Astromech",
 	},
 }
@@ -282,18 +318,18 @@ type review struct {
 	commentary *string
 }
 
-var reviews = make(map[string][]*review)
+var reviews = make(map[episode][]*review)
 
 type Resolver struct{}
 
-func (r *Resolver) Hero(args struct{ Episode string }) *characterResolver {
-	if args.Episode == "EMPIRE" {
+func (r *Resolver) Hero(args struct{ Episode episode }) *characterResolver {
+	if args.Episode == empireEpisode {
 		return &characterResolver{&humanResolver{humanData["1000"]}}
 	}
 	return &characterResolver{&droidResolver{droidData["2001"]}}
 }
 
-func (r *Resolver) Reviews(args struct{ Episode string }) []*reviewResolver {
+func (r *Resolver) Reviews(args struct{ Episode episode }) []*reviewResolver {
 	var l []*reviewResolver
 	for _, review := range reviews[args.Episode] {
 		l = append(l, &reviewResolver{review})
@@ -353,7 +389,7 @@ func (r *Resolver) Starship(args struct{ ID graphql.ID }) *starshipResolver {
 }
 
 func (r *Resolver) CreateReview(args *struct {
-	Episode string
+	Episode episode
 	Review  *reviewInput
 }) *reviewResolver {
 	review := &review{
@@ -374,7 +410,7 @@ type character interface {
 	Name() string
 	Friends() *[]*characterResolver
 	FriendsConnection(friendsConnectionArgs) (*friendsConnectionResolver, error)
-	AppearsIn() []string
+	AppearsIn() []episode
 }
 
 type characterResolver struct {
@@ -423,7 +459,7 @@ func (r *humanResolver) FriendsConnection(args friendsConnectionArgs) (*friendsC
 	return newFriendsConnectionResolver(r.h.Friends, args)
 }
 
-func (r *humanResolver) AppearsIn() []string {
+func (r *humanResolver) AppearsIn() []episode {
 	return r.h.AppearsIn
 }
 
@@ -455,7 +491,7 @@ func (r *droidResolver) FriendsConnection(args friendsConnectionArgs) (*friendsC
 	return newFriendsConnectionResolver(r.d.Friends, args)
 }
 
-func (r *droidResolver) AppearsIn() []string {
+func (r *droidResolver) AppearsIn() []episode {
 	return r.d.AppearsIn
 }