From 228e51b60b6a049e7ff2f447c5dd6630c3531fec Mon Sep 17 00:00:00 2001
From: Matthias <xmatthias@outlook.com>
Date: Mon, 22 Feb 2021 12:11:27 +0100
Subject: [PATCH] Fix #4405

---
 freqtrade/rpc/api_server/webserver.py | 13 +++++++++++++
 tests/rpc/test_rpc_apiserver.py       |  3 ++-
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/freqtrade/rpc/api_server/webserver.py b/freqtrade/rpc/api_server/webserver.py
index f3eaa1ebc..8a5c958e9 100644
--- a/freqtrade/rpc/api_server/webserver.py
+++ b/freqtrade/rpc/api_server/webserver.py
@@ -2,6 +2,7 @@ import logging
 from ipaddress import IPv4Address
 from typing import Any, Dict
 
+import rapidjson
 import uvicorn
 from fastapi import Depends, FastAPI
 from fastapi.middleware.cors import CORSMiddleware
@@ -14,6 +15,17 @@ from freqtrade.rpc.rpc import RPC, RPCException, RPCHandler
 logger = logging.getLogger(__name__)
 
 
+class FTJSONResponse(JSONResponse):
+    media_type = "application/json"
+
+    def render(self, content: Any) -> bytes:
+        """
+        Use rapidjson for responses
+        Handles NaN and Inf / -Inf in a javascript way by default.
+        """
+        return rapidjson.dumps(content).encode("utf-8")
+
+
 class ApiServer(RPCHandler):
 
     _rpc: RPC
@@ -32,6 +44,7 @@ class ApiServer(RPCHandler):
         self.app = FastAPI(title="Freqtrade API",
                            docs_url='/docs' if api_config.get('enable_openapi', False) else None,
                            redoc_url=None,
+                           default_response_class=FTJSONResponse,
                            )
         self.configure_app(self.app, self._config)
 
diff --git a/tests/rpc/test_rpc_apiserver.py b/tests/rpc/test_rpc_apiserver.py
index c4fcf61ea..d7d69d0ae 100644
--- a/tests/rpc/test_rpc_apiserver.py
+++ b/tests/rpc/test_rpc_apiserver.py
@@ -11,6 +11,7 @@ import uvicorn
 from fastapi import FastAPI
 from fastapi.exceptions import HTTPException
 from fastapi.testclient import TestClient
+from numpy import isnan
 from requests.auth import _basic_auth_str
 
 from freqtrade.__init__ import __version__
@@ -797,7 +798,7 @@ def test_api_status(botclient, mocker, ticker, fee, markets):
     assert_response(rc)
     resp_values = rc.json()
     assert len(resp_values) == 1
-    assert resp_values[0]['profit_abs'] is None
+    assert isnan(resp_values[0]['profit_abs'])
 
 
 def test_api_version(botclient):