From 49d863a286c77dbb2b4f4b3e0044296cbd7c1fed Mon Sep 17 00:00:00 2001
From: nanoric <nanoric@qq.com>
Date: Wed, 17 Apr 2019 23:16:33 -0400
Subject: [PATCH] [Add] get_newest_bar_data in database.py [Add]
 get_newest_tick_data in database.py

---
 vnpy/trader/database/database.py | 27 ++++++++++++++++++++++++++-
 1 file changed, 26 insertions(+), 1 deletion(-)

diff --git a/vnpy/trader/database/database.py b/vnpy/trader/database/database.py
index ec765e8d..1b1728bb 100644
--- a/vnpy/trader/database/database.py
+++ b/vnpy/trader/database/database.py
@@ -1,7 +1,7 @@
 from abc import ABC, abstractmethod
 from datetime import datetime
 from enum import Enum
-from typing import Sequence, TYPE_CHECKING
+from typing import Sequence, TYPE_CHECKING, Optional
 
 if TYPE_CHECKING:
     from vnpy.trader.constant import Interval, Exchange  # noqa
@@ -51,3 +51,28 @@ class BaseDatabaseManager(ABC):
         datas: Sequence["TickData"],
     ):
         pass
+
+    @abstractmethod
+    def get_newest_bar_data(
+        self,
+        symbol: str,
+        exchange: "Exchange",
+        interval: "Interval"
+    ) -> Optional["BarData"]:
+        """
+        If there is data in database, return the one with greatest datetime(newest one)
+        otherwise, return None
+        """
+        pass
+
+    @abstractmethod
+    def get_newest_tick_data(
+        self,
+        symbol: str,
+        exchange: "Exchange",
+    ) -> Optional["TickData"]:
+        """
+        If there is data in database, return the one with greatest datetime(newest one)
+        otherwise, return None
+        """
+        pass