From 4838c6f3bf4d198be8ebc81f5f39cf08bfd7c27b Mon Sep 17 00:00:00 2001
From: Richard Musiol <mail@richard-musiol.de>
Date: Sun, 20 Nov 2016 11:27:12 +0100
Subject: [PATCH] fix optional input fields (fixes #25)

---
 graphql_test.go       | 28 +++++++++++++++++++++++++++-
 internal/exec/exec.go |  3 +++
 2 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/graphql_test.go b/graphql_test.go
index ad5c99d70a..5241617875 100644
--- a/graphql_test.go
+++ b/graphql_test.go
@@ -764,7 +764,7 @@ func TestMutation(t *testing.T) {
 			Variables: map[string]interface{}{
 				"ep": "JEDI",
 				"review": map[string]interface{}{
-					"stars":      float64(5),
+					"stars":      5,
 					"commentary": "This is a great movie!",
 				},
 			},
@@ -778,6 +778,32 @@ func TestMutation(t *testing.T) {
 			`,
 		},
 
+		{
+			Schema: starwarsSchema,
+			Query: `
+				mutation CreateReviewForEpisode($ep: Episode!, $review: ReviewInput!) {
+					createReview(episode: $ep, review: $review) {
+						stars
+						commentary
+					}
+				}
+			`,
+			Variables: map[string]interface{}{
+				"ep": "EMPIRE",
+				"review": map[string]interface{}{
+					"stars": float64(4),
+				},
+			},
+			ExpectedResult: `
+				{
+					"createReview": {
+						"stars": 4,
+						"commentary": null
+					}
+				}
+			`,
+		},
+
 		{
 			Schema: starwarsSchema,
 			Query: `
diff --git a/internal/exec/exec.go b/internal/exec/exec.go
index c5d3b1fd7b..ed9daf75ab 100644
--- a/internal/exec/exec.go
+++ b/internal/exec/exec.go
@@ -690,6 +690,9 @@ func coerceMap(r *request, io *common.InputMap, m map[string]interface{}) (map[s
 	for _, iv := range io.Fields {
 		value, ok := m[iv.Name]
 		if !ok {
+			if _, nonNull := unwrapNonNull(iv.Type); !nonNull {
+				continue
+			}
 			if iv.Default == nil {
 				return nil, errors.Errorf("missing %q", iv.Name)
 			}