Add middleware example for Todo

example/todo/schema.graphql

@@ -5,6 +5,7 @@ schema {
 
 type MyQuery {
 	todo(id: Int!): Todo
+	authenticatedTodo(id: Int!): Todo @isAuthenticated
 	lastTodo: Todo
 	todos: [Todo!]!
 }

example/todo/todo.go

@@ -8,18 +8,30 @@ import (
 	"time"
 
 	"github.com/mitchellh/mapstructure"
+	graphql "github.com/vektah/gqlgen/graphql"
 )
 
 func New() Config {
-	r := &resolvers{
-		todos: []Todo{
-			{ID: 1, Text: "A todo not to forget", Done: false},
-			{ID: 2, Text: "This is the most important", Done: false},
-			{ID: 3, Text: "Please do this or else", Done: false},
+	c := Config{
+		Resolvers: &resolvers{
+			todos: []Todo{
+				{ID: 1, Text: "A todo not to forget", Done: false},
+				{ID: 2, Text: "This is the most important", Done: false},
+				{ID: 3, Text: "Please do this or else", Done: false},
+			},
+			lastID: 3,
 		},
-		lastID: 3,
 	}
-	return Config{Resolvers: r}
+	c.Directives.IsAuthenticated = func(ctx context.Context, next graphql.Resolver) (interface{}, error) {
+		rctx := graphql.GetResolverContext(ctx)
+		idVal := rctx.Field.Arguments.ForName("id").Value
+		id, _ := idVal.Value(make(map[string]interface{}))
+		if id.(int64) == 1 {
+			return nil, nil
+		}
+		return next(ctx)
+	}
+	return c
 }
 
 type resolvers struct {
@@ -63,6 +75,10 @@ func (r *QueryResolver) Todos(ctx context.Context) ([]Todo, error) {
 	return r.todos, nil
 }
 
+func (r *QueryResolver) AuthenticatedTodo(ctx context.Context, id int) (*Todo, error) {
+	return r.Todo(ctx, id)
+}
+
 type MutationResolver resolvers
 
 func (r *MutationResolver) CreateTodo(ctx context.Context, todo TodoInput) (Todo, error) {

example/todo/todo_test.go

@@ -127,6 +127,19 @@ func TestTodo(t *testing.T) {
 
 		require.Equal(t, "Completed todo", resp.CreateTodo.Text)
 	})
+
+	t.Run("isAuthenticated directive middleware", func(t *testing.T) {
+		var resp map[string]interface{}
+		c.MustPost(`{ authenticatedTodo(id: 1) { __typename } }`, &resp)
+		val, ok := resp["authenticatedTodo"]
+		require.True(t, ok)
+		require.Nil(t, val)
+
+		c.MustPost(`{ authenticatedTodo(id: 2) { __typename } }`, &resp)
+		val, ok = resp["authenticatedTodo"]
+		require.True(t, ok)
+		require.NotNil(t, val)
+	})
 }
 
 func TestSkipAndIncludeDirectives(t *testing.T) {