From 2ad2d68d7c07d331db858295c743b01215d63697 Mon Sep 17 00:00:00 2001
From: yuyi <yuyi98@163.com>
Date: Fri, 8 Jan 2021 03:21:22 +0800
Subject: [PATCH] json: fix decoding of null map/array (#7936)

---
 vlib/json/json_test.v | 13 +++++++++++++
 vlib/v/gen/json.v     |  4 ++--
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/vlib/json/json_test.v b/vlib/json/json_test.v
index 24e10e899f..c1e875b3b0 100644
--- a/vlib/json/json_test.v
+++ b/vlib/json/json_test.v
@@ -366,3 +366,16 @@ fn test_list_no_items() {
 	assert list.id == 1
 	assert list.items == []
 }
+
+struct Info {
+	id    int
+	items []string
+	maps  map[string]string
+}
+
+fn test_decode_null_object() {
+	info := json.decode(Info, '{"id": 22, "items": null, "maps": null}') or { panic(err) }
+	assert info.id == 22
+	assert '$info.items' == '[]'
+	assert '$info.maps' == '{}'
+}
diff --git a/vlib/v/gen/json.v b/vlib/v/gen/json.v
index 733ab85854..74343ae8b7 100644
--- a/vlib/v/gen/json.v
+++ b/vlib/v/gen/json.v
@@ -222,7 +222,7 @@ fn (mut g Gen) decode_array(value_type table.Type) string {
 '
 	}
 	return '
-	if(root && !cJSON_IsArray(root)) {
+	if(root && !cJSON_IsArray(root) && !cJSON_IsNull(root)) {
 		Option err = v_error( string_add(_SLIT("Json element is not an array: "), tos2(cJSON_PrintUnformatted(root))) );
 		return *(Option_array_$styp *)&err;
 	}
@@ -267,7 +267,7 @@ fn (mut g Gen) decode_map(key_type table.Type, value_type table.Type) string {
 '
 	}
 	return '
-	if(!cJSON_IsObject(root)) {
+	if(!cJSON_IsObject(root) && !cJSON_IsNull(root)) {
 		Option err = v_error( string_add(_SLIT("Json element is not an object: "), tos2(cJSON_PrintUnformatted(root))) );
 		return *(Option_map_${styp}_$styp_v *)&err;
 	}