Revert binance PO fix, since ccxt has fixed this bug.

freqtrade/exchange/binance.py

@@ -7,7 +7,6 @@ from typing import Dict, List, Optional, Tuple
 import arrow
 import ccxt
 
-from freqtrade.constants import BuySell
 from freqtrade.enums import CandleType, MarginMode, PriceType, TradingMode
 from freqtrade.exceptions import DDosProtection, OperationalException, TemporaryError
 from freqtrade.exchange import Exchange
@@ -49,26 +48,6 @@ class Binance(Exchange):
         (TradingMode.FUTURES, MarginMode.ISOLATED)
     ]
 
-    def _get_params(
-        self,
-        side: BuySell,
-        ordertype: str,
-        leverage: float,
-        reduceOnly: bool,
-        time_in_force: str = 'GTC',
-    ) -> Dict:
-        params = super()._get_params(side, ordertype, leverage, reduceOnly, time_in_force)
-        if (
-            time_in_force == 'PO'
-            and ordertype != 'market'
-            and self.trading_mode == TradingMode.SPOT
-            # Only spot can do post only orders
-        ):
-            params.pop('timeInForce')
-            params['postOnly'] = True
-
-        return params
-
     def get_tickers(self, symbols: Optional[List[str]] = None, cached: bool = False) -> Tickers:
         tickers = super().get_tickers(symbols=symbols, cached=cached)
         if self.trading_mode == TradingMode.FUTURES:

tests/exchange/test_binance.py

@@ -15,8 +15,8 @@ from tests.exchange.test_exchange import ccxt_exceptionhandlers
     ('buy', 'limit', 'gtc', {'timeInForce': 'GTC'}),
     ('buy', 'limit', 'IOC', {'timeInForce': 'IOC'}),
     ('buy', 'market', 'IOC', {}),
-    ('buy', 'limit', 'PO', {'postOnly': True}),
-    ('sell', 'limit', 'PO', {'postOnly': True}),
+    ('buy', 'limit', 'PO', {'timeInForce': 'PO'}),
+    ('sell', 'limit', 'PO', {'timeInForce': 'PO'}),
     ('sell', 'market', 'PO', {}),
     ])
 def test__get_params_binance(default_conf, mocker, side, type, time_in_force, expected):