From c082d71a563d7ae33e38e4065b14fa1455502014 Mon Sep 17 00:00:00 2001
From: Learno <learncpp@gmail.com>
Date: Thu, 4 Aug 2016 12:44:11 +0800
Subject: [PATCH] sort support multi key

---
 lualib/mongo.lua     | 16 ++++++++++++++--
 test/testmongodb.lua | 19 +++++++++++--------
 2 files changed, 25 insertions(+), 10 deletions(-)

diff --git a/lualib/mongo.lua b/lualib/mongo.lua
index 7393ebbd..3be7d18a 100644
--- a/lualib/mongo.lua
+++ b/lualib/mongo.lua
@@ -7,6 +7,7 @@ local md5 =	require	"md5"
 local crypt = require "crypt"
 local rawget = rawget
 local assert = assert
+local table = table
 
 local bson_encode =	bson.encode
 local bson_encode_order	= bson.encode_order
@@ -395,8 +396,19 @@ function mongo_collection:find(query, selector)
 	} ,	cursor_meta)
 end
 
-function mongo_cursor:sort(key_list)
-	self.__sortquery = bson_encode {['$query'] = self.__query, ['$orderby'] = key_list}
+-- cursor:sort { key = 1 } or cursor:sort( {key1 = 1}, {key2 = -1})
+function mongo_cursor:sort(key, key_v, ...)
+	if key_v then
+		local key_list = {}
+		for _, kp in ipairs {key, key_v, ...} do
+			local next_func, t = pairs(kp)
+			local k, v = next_func(t, v)	-- The first key pair
+			table.insert(key_list, k)
+			table.insert(key_list, v)
+		end
+		key = bson_encode_order(table.unpack(key_list))
+	end
+	self.__sortquery = bson_encode {['$query'] = self.__query, ['$orderby'] = key}
 	return self
 end
 
diff --git a/test/testmongodb.lua b/test/testmongodb.lua
index d1fed034..bce37683 100644
--- a/test/testmongodb.lua
+++ b/test/testmongodb.lua
@@ -38,24 +38,27 @@ function test_find_and_remove()
 	db[db_name].testdb:dropIndex("*")
 	db[db_name].testdb:drop()
 
-	db[db_name].testdb:ensureIndex({test_key = 1}, {unique = true, name = "test_key_index"})
+	db[db_name].testdb:ensureIndex({test_key = 1}, {test_key2 = -1}, {unique = true, name = "test_index"})
 
-	local ret = db[db_name].testdb:safe_insert({test_key = 1})
+	local ret = db[db_name].testdb:safe_insert({test_key = 1, test_key2 = 1})
 	assert(ret and ret.n == 1)
 
-	local ret = db[db_name].testdb:safe_insert({test_key = 2})
+	local ret = db[db_name].testdb:safe_insert({test_key = 1, test_key2 = 2})
 	assert(ret and ret.n == 1)
 
-	local ret = db[db_name].testdb:findOne({test_key = 1})
-	assert(ret and ret.test_key == 1)
+	local ret = db[db_name].testdb:safe_insert({test_key = 2, test_key2 = 3})
+	assert(ret and ret.n == 1)
 
-	local ret = db[db_name].testdb:find({test_key = {['$gt'] = 0}}):sort({test_key = -1}):skip(1):limit(1)
- 	assert(ret:count() == 2)
+	local ret = db[db_name].testdb:findOne({test_key2 = 1})
+	assert(ret and ret.test_key2 == 1)
+
+	local ret = db[db_name].testdb:find({test_key2 = {['$gt'] = 0}}):sort({test_key = 1}, {test_key2 = -1}):skip(1):limit(1)
+ 	assert(ret:count() == 3)
  	assert(ret:count(true) == 1)
 	if ret:hasNext() then
 		ret = ret:next()
 	end
-	assert(ret and ret.test_key == 1)
+	assert(ret and ret.test_key2 == 1)
 
 	db[db_name].testdb:delete({test_key = 1})
 	db[db_name].testdb:delete({test_key = 2})