Merge pull request #244 from learno/lua53

扩展mongo库对sort, skip, limit, count方法的支持

lualib/mongo.lua

@@ -279,9 +279,45 @@ function mongo_collection:find(query, selector)
 		__cursor = nil,
 		__document = {},
 		__flags	= 0,
+		__skip = 0,
+		__sortquery = nil,
+		__limit = 0,
 	} ,	cursor_meta)
 end
 
+function mongo_cursor:sort(key_list)
+	self.__sortquery = bson_encode {['$query'] = self.__query, ['$orderby'] = key_list}
+	return self
+end
+
+function mongo_cursor:skip(amount)
+	self.__skip = amount
+	return self
+end
+
+function mongo_cursor:limit(amount)
+	self.__limit = amount
+	return self
+end
+
+function mongo_cursor:count(with_limit_and_skip)
+	local cmd = {
+		'count', self.__collection.name,
+		'query', self.__query,
+	}
+	if with_limit_and_skip then
+		local len = #cmd
+		cmd[len+1] = 'limit'
+		cmd[len+2] = self.__limit
+		cmd[len+3] = 'skip'
+		cmd[len+4] = self.__skip
+	end
+	local ret = self.__collection.database:runCommand(table.unpack(cmd))
+	assert(ret and ret.ok == 1)
+	return ret.n
+end
+
+
 -- collection:createIndex({username = 1}, {unique = true})
 function mongo_collection:createIndex(keys, option)
 	local name = option.name
@@ -348,10 +384,11 @@ function mongo_cursor:hasNext()
 		local sock = conn.__sock
 		local pack
 		if self.__data == nil then
-			pack = driver.query(request_id,	self.__flags, self.__collection.full_name,0,0,self.__query,self.__selector)
+			local query = self.__sortquery or self.__query
+			pack = driver.query(request_id, self.__flags, self.__collection.full_name, self.__skip, -self.__limit, query, self.__selector)
 		else
 			if self.__cursor then
-				pack = driver.more(request_id, self.__collection.full_name,0,self.__cursor)
+				pack = driver.more(request_id, self.__collection.full_name, -self.__limit, self.__cursor)
 			else
 				-- no more
 				self.__document	= nil

test/testmongodb.lua

@@ -43,10 +43,22 @@ function test_find_and_remove()
 	local ret = db[db_name].testdb:safe_insert({test_key = 1})
 	assert(ret and ret.n == 1)
 
+	local ret = db[db_name].testdb:safe_insert({test_key = 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:find({test_key = {['$gt'] = 0}}):sort({test_key = -1}):skip(1):limit(1)
+ 	assert(ret:count() == 2)
+ 	assert(ret:count(true) == 1)
+	if ret:hasNext() then
+		ret = ret:next()
+	end
+	assert(ret and ret.test_key == 1)
+
 	db[db_name].testdb:delete({test_key = 1})
+	db[db_name].testdb:delete({test_key = 2})
 
 	local ret = db[db_name].testdb:findOne({test_key = 1})
 	assert(ret == nil)