Fix directives on fields with custom scalars

codegen/input.gotpl

@@ -35,7 +35,7 @@
 					if err != nil {
 						return it, err
 					}
-					if data, ok := tmp.({{ $field.TypeReference.GO }}) ; ok {
+					if data, ok := tmp.({{ $field.TypeReference.GO | ref }}) ; ok {
 						it.{{$field.GoFieldName}} = data
 					} else {
 						return it, fmt.Errorf(`unexpected type %T from directive, should be {{ $field.TypeReference.GO }}`, tmp)

codegen/testserver/gqlgen.yml

@@ -38,3 +38,5 @@ models:
     model: "github.com/99designs/gqlgen/codegen/testserver.Error"
   EmbeddedPointer:
     model: "github.com/99designs/gqlgen/codegen/testserver.EmbeddedPointerModel"
+  ThirdParty:
+    model: "github.com/99designs/gqlgen/codegen/testserver.ThirdParty"

codegen/testserver/schema.graphql

@@ -70,10 +70,13 @@ input OuterInput {
     inner: InnerInput!
 }
 
+scalar ThirdParty
+
 input InputDirectives {
     text: String! @length(min: 0, max: 7, message: "not valid")
     inner: InnerDirectives!
     innerNullable: InnerDirectives
+    thirdParty: ThirdParty @length(min: 0, max: 7, message: "not valid")
 }
 
 input InnerDirectives {

codegen/testserver/thirdparty.go

@@ -0,0 +1,30 @@
+package testserver
+
+import (
+	"fmt"
+	"github.com/99designs/gqlgen/graphql"
+	"io"
+	"strconv"
+)
+
+type ThirdParty struct {
+	str string
+}
+
+func MarshalThirdParty(tp ThirdParty) graphql.Marshaler {
+	return graphql.WriterFunc(func(w io.Writer) {
+		_, err := io.WriteString(w, strconv.Quote(tp.str))
+		if err != nil {
+			panic(err)
+		}
+	})
+}
+
+func UnmarshalThirdParty(input interface{}) (ThirdParty, error) {
+	switch input := input.(type) {
+	case string:
+		return ThirdParty{str: input}, nil
+	default:
+		return ThirdParty{}, fmt.Errorf("unknown type for input: %s", input)
+	}
+}