Add support for null vs missing input value

graphql_test.go

@@ -2997,7 +2997,7 @@ func TestInput(t *testing.T) {
 	})
 }
 
-type inputArgumentsHello struct {}
+type inputArgumentsHello struct{}
 
 type inputArgumentsScalarMismatch1 struct{}
 
@@ -3755,3 +3755,185 @@ func TestPointerReturnForNonNull(t *testing.T) {
 		},
 	})
 }
+
+type nullableInput struct {
+	String graphql.NullString
+	Int    graphql.NullInt
+	Bool   graphql.NullBool
+	Time   graphql.NullTime
+	Float  graphql.NullFloat
+}
+
+type nullableResult struct {
+	String string
+	Int    string
+	Bool   string
+	Time   string
+	Float  string
+}
+
+type nullableResolver struct {
+}
+
+func (r *nullableResolver) TestNullables(args struct {
+	Input *nullableInput
+}) nullableResult {
+	var res nullableResult
+	if args.Input.String.Set {
+		if args.Input.String.Value == nil {
+			res.String = "<nil>"
+		} else {
+			res.String = *args.Input.String.Value
+		}
+	}
+
+	if args.Input.Int.Set {
+		if args.Input.Int.Value == nil {
+			res.Int = "<nil>"
+		} else {
+			res.Int = fmt.Sprintf("%d", *args.Input.Int.Value)
+		}
+	}
+
+	if args.Input.Float.Set {
+		if args.Input.Float.Value == nil {
+			res.Float = "<nil>"
+		} else {
+			res.Float = fmt.Sprintf("%.2f", *args.Input.Float.Value)
+		}
+	}
+
+	if args.Input.Bool.Set {
+		if args.Input.Bool.Value == nil {
+			res.Bool = "<nil>"
+		} else {
+			res.Bool = fmt.Sprintf("%t", *args.Input.Bool.Value)
+		}
+	}
+
+	if args.Input.Time.Set {
+		if args.Input.Time.Value == nil {
+			res.Time = "<nil>"
+		} else {
+			res.Time = args.Input.Time.Value.Format(time.RFC3339)
+		}
+	}
+
+	return res
+}
+
+func TestNullable(t *testing.T) {
+	schema := `
+	scalar Time
+
+	input MyInput {
+		string: String
+		int: Int
+		float: Float
+		bool: Boolean
+		time: Time
+	}
+
+	type Result {
+		string: String!
+		int: String!
+		float: String!
+		bool: String!
+		time: String!
+	}
+
+	type Query {
+		testNullables(input: MyInput): Result!
+	}
+	`
+
+	gqltesting.RunTests(t, []*gqltesting.Test{
+		{
+			Schema: graphql.MustParseSchema(schema, &nullableResolver{}, graphql.UseFieldResolvers()),
+			Query: `
+				query {
+					testNullables(input: {
+						string: "test"
+						int: 1234
+						float: 42.42
+						bool: true
+						time: "2021-01-02T15:04:05Z"
+					}) {
+						string
+						int
+						float
+						bool
+						time
+					}
+				}
+			`,
+			ExpectedResult: `
+				{
+					"testNullables": {
+						"string": "test",
+						"int": "1234",
+						"float": "42.42",
+						"bool": "true",
+						"time": "2021-01-02T15:04:05Z"
+					}
+				}
+			`,
+		},
+		{
+			Schema: graphql.MustParseSchema(schema, &nullableResolver{}, graphql.UseFieldResolvers()),
+			Query: `
+				query {
+					testNullables(input: {
+						string: null
+						int: null
+						float: null
+						bool: null
+						time: null
+					}) {
+						string
+						int
+						float
+						bool
+						time
+					}
+				}
+			`,
+			ExpectedResult: `
+				{
+					"testNullables": {
+						"string": "<nil>",
+						"int": "<nil>",
+						"float": "<nil>",
+						"bool": "<nil>",
+						"time": "<nil>"
+					}
+				}
+			`,
+		},
+		{
+			Schema: graphql.MustParseSchema(schema, &nullableResolver{}, graphql.UseFieldResolvers()),
+			Query: `
+				query {
+					testNullables(input: {}) {
+						string
+						int
+						float
+						bool
+						time
+					}
+				}
+			`,
+			ExpectedResult: `
+				{
+					"testNullables": {
+						"string": "",
+						"int": "",
+						"float": "",
+						"bool": "",
+						"time": ""
+					}
+				}
+			`,
+		},
+	})
+}

internal/exec/packer/packer.go

@@ -78,24 +78,37 @@ func (b *Builder) assignPacker(target *packer, schemaType common.Type, reflectTy
 func (b *Builder) makePacker(schemaType common.Type, reflectType reflect.Type) (packer, error) {
 	t, nonNull := unwrapNonNull(schemaType)
 	if !nonNull {
-		if reflectType.Kind() != reflect.Ptr {
-			return nil, fmt.Errorf("%s is not a pointer", reflectType)
-		}
-		elemType := reflectType.Elem()
-		addPtr := true
-		if _, ok := t.(*schema.InputObject); ok {
-			elemType = reflectType // keep pointer for input objects
-			addPtr = false
-		}
-		elem, err := b.makeNonNullPacker(t, elemType)
-		if err != nil {
-			return nil, err
+		if reflectType.Kind() == reflect.Ptr {
+			elemType := reflectType.Elem()
+			addPtr := true
+			if _, ok := t.(*schema.InputObject); ok {
+				elemType = reflectType // keep pointer for input objects
+				addPtr = false
+			}
+			elem, err := b.makeNonNullPacker(t, elemType)
+			if err != nil {
+				return nil, err
+			}
+			return &nullPacker{
+				elemPacker: elem,
+				valueType:  reflectType,
+				addPtr:     addPtr,
+			}, nil
+		} else if isNullable(reflectType) {
+			elemType := reflectType
+			addPtr := false
+			elem, err := b.makeNonNullPacker(t, elemType)
+			if err != nil {
+				return nil, err
+			}
+			return &nullPacker{
+				elemPacker: elem,
+				valueType:  reflectType,
+				addPtr:     addPtr,
+			}, nil
+		} else {
+			return nil, fmt.Errorf("%s is not a pointer or a nullable type", reflectType)
 		}
-		return &nullPacker{
-			elemPacker: elem,
-			valueType:  reflectType,
-			addPtr:     addPtr,
-		}, nil
 	}
 
 	return b.makeNonNullPacker(t, reflectType)
@@ -266,7 +279,7 @@ type nullPacker struct {
 }
 
 func (p *nullPacker) Pack(value interface{}) (reflect.Value, error) {
-	if value == nil {
+	if value == nil && !isNullable(p.valueType) {
 		return reflect.Zero(p.valueType), nil
 	}
 
@@ -305,7 +318,7 @@ type unmarshalerPacker struct {
 }
 
 func (p *unmarshalerPacker) Pack(value interface{}) (reflect.Value, error) {
-	if value == nil {
+	if value == nil && !isNullable(p.ValueType) {
 		return reflect.Value{}, errors.Errorf("got null for non-null")
 	}
 
@@ -369,3 +382,14 @@ func unwrapNonNull(t common.Type) (common.Type, bool) {
 func stripUnderscore(s string) string {
 	return strings.Replace(s, "_", "", -1)
 }
+
+// NullUnmarshaller is an unmarshaller that can handle a nil input
+type NullUnmarshaller interface {
+	Unmarshaler
+	Nullable()
+}
+
+func isNullable(t reflect.Type) bool {
+	_, ok := reflect.New(t).Interface().(NullUnmarshaller)
+	return ok
+}