Fixing database issues

1. if database is defined in config file, it currently tosses an exception that only export file or db is defined
2. if trades are loaded from databases, plot crashes with an exception 'cannot compare tz-naive and tz-aware datetime-like objects'
3. if Trade is not closed, crashes with exception that NoneType has no field timestamp

all should be fixed

scripts/plot_dataframe.py

@@ -24,15 +24,17 @@ Example of usage:
 > python3 scripts/plot_dataframe.py --pair BTC/EUR -d user_data/data/ --indicators1 sma,ema3
 --indicators2 fastk,fastd
 """
+import json
 import logging
 import sys
-import json
-from pathlib import Path
 from argparse import Namespace
+from pathlib import Path
 from typing import Dict, List, Any
 
 import pandas as pd
 import plotly.graph_objs as go
+import pytz
+
 from plotly import tools
 from plotly.offline import plot
 
@@ -47,6 +49,8 @@ from freqtrade.persistence import Trade
 logger = logging.getLogger(__name__)
 _CONF: Dict[str, Any] = {}
 
+timeZone = pytz.UTC
+
 
 def load_trades(args: Namespace, pair: str, timerange: TimeRange) -> pd.DataFrame:
     trades: pd.DataFrame = pd.DataFrame()
@@ -54,14 +58,18 @@ def load_trades(args: Namespace, pair: str, timerange: TimeRange) -> pd.DataFram
         persistence.init(_CONF)
         columns = ["pair", "profit", "opents", "closets", "open_rate", "close_rate", "duration"]
 
+        for x in Trade.query.all():
+            print("date: {}".format(x.open_date))
+
         trades = pd.DataFrame([(t.pair, t.calc_profit(),
-                                t.open_date, t.close_date,
+                                t.open_date.replace(tzinfo=timeZone),
+                                t.close_date.replace(tzinfo=timeZone) if t.close_date else None,
                                 t.open_rate, t.close_rate,
-                                t.close_date.timestamp() - t.open_date.timestamp())
+                                t.close_date.timestamp() - t.open_date.timestamp() if t.close_date else None)
                                for t in Trade.query.filter(Trade.pair.is_(pair)).all()],
                               columns=columns)
 
-    if args.exportfilename:
+    elif args.exportfilename:
         file = Path(args.exportfilename)
         # must align with columns in backtest.py
         columns = ["pair", "profit", "opents", "closets", "index", "duration",
@@ -97,6 +105,7 @@ def plot_analyzed_dataframe(args: Namespace) -> None:
     # Load the configuration
     _CONF.update(setup_configuration(args))
 
+    print(_CONF)
     # Set the pair to audit
     pair = args.pair
 
@@ -136,19 +145,19 @@ def plot_analyzed_dataframe(args: Namespace) -> None:
             pairs=[pair],
             ticker_interval=tick_interval,
             refresh_pairs=_CONF.get('refresh_pairs', False),
-            timerange=timerange
+            timerange=timerange,
+            exchange=Exchange(_CONF)
         )
 
         # No ticker found, or impossible to download
         if tickers == {}:
             exit()
 
-    if args.db_url and args.exportfilename:
-        logger.critical("Can only specify --db-url or --export-filename")
     # Get trades already made from the DB
     trades = load_trades(args, pair, timerange)
 
     dataframes = analyze.tickerdata_to_dataframe(tickers)
+
     dataframe = dataframes[pair]
     dataframe = analyze.populate_buy_trend(dataframe)
     dataframe = analyze.populate_sell_trend(dataframe)
@@ -157,6 +166,7 @@ def plot_analyzed_dataframe(args: Namespace) -> None:
         logger.warning('Ticker contained more than %s candles as defined '
                        'with --plot-limit, clipping.', args.plot_limit)
     dataframe = dataframe.tail(args.plot_limit)
+
     trades = trades.loc[trades['opents'] >= dataframe.iloc[0]['date']]
     fig = generate_graph(
         pair=pair,