Fix bug in exporting types with reverse predicates. (#4857)

< > brackets are needed around the type name. They were missing.

Author: martinmr

worker/export.go

@@ -333,7 +333,15 @@ func toType(attr string, update pb.TypeUpdate) (*bpb.KVList, error) {
 func fieldToString(update *pb.SchemaUpdate) string {
 	var builder strings.Builder
 	x.Check2(builder.WriteString("\t"))
-	x.Check2(builder.WriteString(update.Predicate))
+	// While exporting type definitions, "<" and ">" brackets must be written around
+	// the name of everse predicates or Dgraph won't be able to parse the exported schema.
+	if strings.HasPrefix(update.Predicate, "~") {
+		x.Check2(builder.WriteString("<"))
+		x.Check2(builder.WriteString(update.Predicate))
+		x.Check2(builder.WriteString(">"))
+	} else {
+		x.Check2(builder.WriteString(update.Predicate))
+	}
 	x.Check2(builder.WriteString("\n"))
 	return builder.String()
 }

worker/export_test.go

@@ -57,6 +57,9 @@ var personType = &pb.TypeUpdate{
 		{
 			Predicate: "friend",
 		},
+		{
+			Predicate: "~friend",
+		},
 		{
 			Predicate: "friend_not_served",
 		},