Allow empty hstore keys

See pgx commit: 56f4f0b9d3

hstore.go

@@ -297,13 +297,9 @@ func parseHstore(s string) (k []string, v []Text, err error) {
 		case hsKey:
 			switch r {
 			case '"': //End of the key
-				if buf.Len() == 0 {
-					err = errors.New("Empty Key is invalid")
-				} else {
-					keys = append(keys, buf.String())
-					buf = bytes.Buffer{}
-					state = hsSep
-				}
+				keys = append(keys, buf.String())
+				buf = bytes.Buffer{}
+				state = hsSep
 			case '\\': //Potential escaped character
 				n, end := p.Consume()
 				switch {

hstore_test.go

@@ -19,6 +19,7 @@ func TestHstoreTranscode(t *testing.T) {
 		&pgtype.Hstore{Map: map[string]pgtype.Text{"foo": text("bar"), "baz": text("quz")}, Status: pgtype.Present},
 		&pgtype.Hstore{Map: map[string]pgtype.Text{"NULL": text("bar")}, Status: pgtype.Present},
 		&pgtype.Hstore{Map: map[string]pgtype.Text{"foo": text("NULL")}, Status: pgtype.Present},
+		&pgtype.Hstore{Map: map[string]pgtype.Text{"": text("bar")}, Status: pgtype.Present},
 		&pgtype.Hstore{Status: pgtype.Null},
 	}