From 4cf60d6f531c0b4803b339c83630a7d897135c06 Mon Sep 17 00:00:00 2001
From: Baha Aiman <bahaaiman@google.com>
Date: Sat, 9 Sep 2023 20:04:43 -0700
Subject: [PATCH 1/3] fix(datastore): Allow saving nested byte slice

---
 datastore/datastore_test.go | 69 +++++++++++++++++++++++++++++++++++++
 datastore/prop.go           |  2 +-
 2 files changed, 70 insertions(+), 1 deletion(-)

diff --git a/datastore/datastore_test.go b/datastore/datastore_test.go
index 550336319e53..03755e397d5c 100644
--- a/datastore/datastore_test.go
+++ b/datastore/datastore_test.go
@@ -614,6 +614,75 @@ func TestPutInvalidEntity(t *testing.T) {
 	})
 }
 
+func TestPutNestedArray(t *testing.T) {
+	type InnerByte struct {
+		ArrByte []byte
+	}
+
+	type OuterByte struct {
+		InnerArr []InnerByte `datastore:"arrbyte,flatten"`
+	}
+
+	type InnerStr struct {
+		ArrStr []string
+	}
+
+	type OuterStr struct {
+		InnerArr []InnerStr `datastore:"arrstr,flatten"`
+	}
+
+	ctx := context.Background()
+	client := &Client{
+		client: &fakeDatastoreClient{
+			commit: func(req *pb.CommitRequest) (*pb.CommitResponse, error) {
+				return &pb.CommitResponse{}, nil
+			},
+		},
+	}
+
+	testcases := []struct {
+		desc        string
+		src         interface{}
+		key         *Key
+		wantFailure bool
+		wantErrMsg  string
+	}{
+		{
+			desc: "Nested byte slice should pass",
+			src: &OuterByte{
+				InnerArr: []InnerByte{
+					{
+						ArrByte: []byte("Test string"),
+					},
+				},
+			},
+			key: NameKey("OuterByte", "OuterByte1", nil),
+		},
+		{
+			desc: "Nested slice not of byte type should fail",
+			src: &OuterStr{
+				InnerArr: []InnerStr{
+					{
+						ArrStr: []string{"a", "b"},
+					},
+				},
+			},
+			key:         NameKey("OuterStr", "OuterStr1", nil),
+			wantFailure: true,
+			wantErrMsg:  "flattening nested structs leads to a slice of slices",
+		},
+	}
+
+	for _, tc := range testcases {
+		_, gotErr := client.Put(ctx, tc.key, tc.src)
+		gotFailure := gotErr != nil
+		if gotFailure != tc.wantFailure ||
+			(gotErr != nil && !strings.Contains(gotErr.Error(), tc.wantErrMsg)) {
+			t.Errorf("%q: Mismatch in error got: %v, want: %q", tc.desc, gotErr, tc.wantErrMsg)
+		}
+	}
+}
+
 func TestDeferred(t *testing.T) {
 	type Ent struct {
 		A int
diff --git a/datastore/prop.go b/datastore/prop.go
index ff7466bf8a33..bab830aebaf8 100644
--- a/datastore/prop.go
+++ b/datastore/prop.go
@@ -183,7 +183,7 @@ func validateChildType(t reflect.Type, fieldName string, flatten, prevSlice bool
 
 	switch t.Kind() {
 	case reflect.Slice:
-		if flatten && prevSlice {
+		if flatten && prevSlice && t.Elem().Kind() != reflect.Uint8 {
 			return fmt.Errorf("datastore: flattening nested structs leads to a slice of slices: field %q", fieldName)
 		}
 		return validateChildType(t.Elem(), fieldName, flatten, true, prevTypes)

From 49fac9a14052bdbffdf04380b859aa13d009b44e Mon Sep 17 00:00:00 2001
From: Baha Aiman <bahaaiman@google.com>
Date: Wed, 13 Sep 2023 10:15:38 -0700
Subject: [PATCH 2/3] fix(datastore): Adding comment

---
 datastore/prop.go | 1 +
 1 file changed, 1 insertion(+)

diff --git a/datastore/prop.go b/datastore/prop.go
index bab830aebaf8..26e26ae5dd82 100644
--- a/datastore/prop.go
+++ b/datastore/prop.go
@@ -183,6 +183,7 @@ func validateChildType(t reflect.Type, fieldName string, flatten, prevSlice bool
 
 	switch t.Kind() {
 	case reflect.Slice:
+		// Uint8 is an alias for byte. A slice of bytes is acceptable. A slice of others types is not.
 		if flatten && prevSlice && t.Elem().Kind() != reflect.Uint8 {
 			return fmt.Errorf("datastore: flattening nested structs leads to a slice of slices: field %q", fieldName)
 		}

From 3e559d0bb2d475fb037601f369a609eb911a2942 Mon Sep 17 00:00:00 2001
From: Baha Aiman <bahaaiman@google.com>
Date: Fri, 15 Sep 2023 10:41:11 -0700
Subject: [PATCH 3/3] fix(datastore): Assert returned value

---
 datastore/datastore_test.go | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/datastore/datastore_test.go b/datastore/datastore_test.go
index 03755e397d5c..e483936c3e58 100644
--- a/datastore/datastore_test.go
+++ b/datastore/datastore_test.go
@@ -674,12 +674,15 @@ func TestPutNestedArray(t *testing.T) {
 	}
 
 	for _, tc := range testcases {
-		_, gotErr := client.Put(ctx, tc.key, tc.src)
+		gotKey, gotErr := client.Put(ctx, tc.key, tc.src)
 		gotFailure := gotErr != nil
 		if gotFailure != tc.wantFailure ||
 			(gotErr != nil && !strings.Contains(gotErr.Error(), tc.wantErrMsg)) {
 			t.Errorf("%q: Mismatch in error got: %v, want: %q", tc.desc, gotErr, tc.wantErrMsg)
 		}
+		if gotErr == nil && !gotKey.Equal(tc.key) {
+			t.Errorf("%q: Mismatch in key got: %v, want: %q", tc.desc, gotKey, tc.key)
+		}
 	}
 }