From b94f2afe22033bcb4b1a68d64adab00986abeea4 Mon Sep 17 00:00:00 2001
From: Richard Musiol <mail@richard-musiol.de>
Date: Mon, 21 Nov 2016 12:43:28 +0100
Subject: [PATCH] improved support for null

---
 graphql_test.go           |  9 +++++++++
 internal/common/values.go |  2 ++
 internal/exec/exec.go     |  5 ++++-
 internal/exec/packer.go   | 19 ++++++++++++-------
 4 files changed, 27 insertions(+), 8 deletions(-)

diff --git a/graphql_test.go b/graphql_test.go
index 6db8880da1..2e17ef3f61 100644
--- a/graphql_test.go
+++ b/graphql_test.go
@@ -1258,6 +1258,10 @@ func (r *inputResolver) Boolean(args *struct{ Value bool }) bool {
 	return args.Value
 }
 
+func (r *inputResolver) Nullable(args *struct{ Value *int32 }) *int32 {
+	return args.Value
+}
+
 func (r *inputResolver) List(args *struct{ Value []*struct{ V int32 } }) []int32 {
 	l := make([]int32, len(args.Value))
 	for i, entry := range args.Value {
@@ -1277,6 +1281,7 @@ func TestInput(t *testing.T) {
 			float(value: Float!): Float!
 			string(value: String!): String!
 			boolean(value: Boolean!): Boolean!
+			nullable(value: Int): Int
 			list(value: [Input!]!): [Int!]!
 		}
 
@@ -1295,6 +1300,8 @@ func TestInput(t *testing.T) {
 					float2: float(value: 42.5)
 					string(value: "foo")
 					boolean(value: true)
+					nullable1: nullable(value: 42)
+					nullable2: nullable(value: null)
 					list(value: [{v: 41}, {v: 42}, {v: 43}])
 				}
 			`,
@@ -1306,6 +1313,8 @@ func TestInput(t *testing.T) {
 					"float2": 42.5,
 					"string": "foo",
 					"boolean": true,
+					"nullable1": 42,
+					"nullable2": null,
 					"list": [41, 42, 43]
 				}
 			`,
diff --git a/internal/common/values.go b/internal/common/values.go
index f1ad2bd679..4b871464f2 100644
--- a/internal/common/values.go
+++ b/internal/common/values.go
@@ -54,6 +54,8 @@ func ParseValue(l *lexer.Lexer, constOnly bool) interface{} {
 			return true
 		case "false":
 			return false
+		case "null":
+			return nil
 		default:
 			return ident
 		}
diff --git a/internal/exec/exec.go b/internal/exec/exec.go
index f7b17c62dc..f805081c94 100644
--- a/internal/exec/exec.go
+++ b/internal/exec/exec.go
@@ -632,7 +632,10 @@ func coerceValue(r *request, typ common.Type, value interface{}) (interface{}, e
 		return r.vars[string(v)], nil
 	}
 
-	t, _ := unwrapNonNull(typ)
+	t, nonNull := unwrapNonNull(typ)
+	if !nonNull && value == nil {
+		return nil, nil
+	}
 	switch t := t.(type) {
 	case *scalar:
 		v, err := t.coerceInput(value)
diff --git a/internal/exec/packer.go b/internal/exec/packer.go
index f03720990f..bc097edf1a 100644
--- a/internal/exec/packer.go
+++ b/internal/exec/packer.go
@@ -28,7 +28,8 @@ func makePacker(s *schema.Schema, schemaType common.Type, hasDefault bool, refle
 			return nil, fmt.Errorf("wrong type, expected %s", want)
 		}
 		return &valuePacker{
-			nonNull: nonNull,
+			valueType: reflectType,
+			nonNull:   nonNull,
 		}, nil
 	case *schema.Enum:
 		want := reflect.TypeOf("")
@@ -39,7 +40,8 @@ func makePacker(s *schema.Schema, schemaType common.Type, hasDefault bool, refle
 			return nil, fmt.Errorf("wrong type, expected %s", want)
 		}
 		return &valuePacker{
-			nonNull: nonNull,
+			valueType: reflectType,
+			nonNull:   nonNull,
 		}, nil
 	case *schema.InputObject:
 		e, err := makeStructPacker(s, &t.InputMap, reflectType)
@@ -150,15 +152,18 @@ func (e *listPacker) pack(value interface{}) reflect.Value {
 }
 
 type valuePacker struct {
-	nonNull bool
+	valueType reflect.Type
+	nonNull   bool
 }
 
 func (p *valuePacker) pack(value interface{}) reflect.Value {
-	v := reflect.ValueOf(value)
 	if !p.nonNull {
-		ptr := reflect.New(v.Type())
-		ptr.Elem().Set(v)
+		if value == nil {
+			return reflect.Zero(p.valueType)
+		}
+		ptr := reflect.New(p.valueType.Elem())
+		ptr.Elem().Set(reflect.ValueOf(value))
 		return ptr
 	}
-	return v
+	return reflect.ValueOf(value)
 }