From 1f5c22ae3a503bafe6eaa9c0aadfa63ca26872f1 Mon Sep 17 00:00:00 2001
From: Ibrahim Jarif <ibrahim@dgraph.io>
Date: Thu, 1 Oct 2020 12:35:29 +0530
Subject: [PATCH 1/2] fix(gqlParser): Handle strings with only whitespace

---
 gql/parser.go | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/gql/parser.go b/gql/parser.go
index e3788416206..9574886fa82 100644
--- a/gql/parser.go
+++ b/gql/parser.go
@@ -372,9 +372,6 @@ func substituteVariables(gq *GraphQuery, vmap varMap) error {
 
 	idVal, ok := gq.Args["id"]
 	if ok && len(gq.UID) == 0 {
-		if idVal == "" {
-			return errors.Errorf("Id can't be empty")
-		}
 		uids, err := parseID(idVal)
 		if err != nil {
 			return err
@@ -487,9 +484,6 @@ func substituteVariablesFilter(f *FilterTree, vmap varMap) error {
 				if !ok {
 					return errors.Errorf("Couldn't find value for GraphQL variable: [%s]", v.Value)
 				}
-				if idVal.Value == "" {
-					return errors.Errorf("Id can't be empty")
-				}
 				uids, err := parseID(idVal.Value)
 				if err != nil {
 					return err
@@ -2350,8 +2344,11 @@ loop:
 // Parses ID list. Only used for GraphQL variables.
 // TODO - Maybe get rid of this by lexing individual IDs.
 func parseID(val string) ([]uint64, error) {
-	var uids []uint64
 	val = x.WhiteSpace.Replace(val)
+	if val == "" {
+		return nil, errors.Errorf("ID can't be empty")
+	}
+	var uids []uint64
 	if val[0] != '[' {
 		uid, err := strconv.ParseUint(val, 0, 64)
 		if err != nil {

From 17ea052016c6cb40aff778f7be04cb5b9dfe3689 Mon Sep 17 00:00:00 2001
From: Ibrahim Jarif <ibrahim@dgraph.io>
Date: Thu, 1 Oct 2020 14:27:21 +0530
Subject: [PATCH 2/2] Add test

---
 gql/parser_test.go | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/gql/parser_test.go b/gql/parser_test.go
index 3d49bef9959..8384628d9ed 100644
--- a/gql/parser_test.go
+++ b/gql/parser_test.go
@@ -5443,3 +5443,13 @@ func TestBadCascadeParameterized(t *testing.T) {
 		require.Error(t, err)
 	}
 }
+
+func TestEmptyId(t *testing.T) {
+	q := "query me($a: string) { q(func: uid($a)) { name }}"
+	r := Request{
+		Str:       q,
+		Variables: map[string]string{"$a": "   "},
+	}
+	_, err := Parse(r)
+	require.Error(t, err, "ID cannot be empty")
+}