add basic logging options to HydraApp

hydralit/hydra_app.py

@@ -1,5 +1,7 @@
 from typing import Dict
 import streamlit as st
+from streamlit.logger import get_logger
+import traceback
 from datetime import datetime, timedelta, timezone
 from hydralit.sessionstate import SessionState
 from hydralit.loading_app import LoadingApp
@@ -30,7 +32,9 @@ def __init__(self,
         use_banner_images=None,
         banner_spacing=None, 
         clear_cross_app_sessions=True, 
-        session_params=None):
+        session_params=None,
+        logger=None,
+        log_level='WARNING'):
         """
         A class to create an Multi-app Streamlit application. This class will be the host application for multiple applications that are added after instancing.
         The secret saurce to making the different apps work together comes from the use of a global session store that is shared with any HydraHeadApp that is added to the parent HydraApp.
@@ -82,7 +86,10 @@ def __init__(self,
             A flag to indicate if the local session store values within individual apps should be cleared when moving to another app, if set to False, when loading sidebar controls, will be a difference between expected and selected.
         session_params: Dict
             A Dict of parameter name and default values that will be added to the global session store, these parameters will be available to all child applications and they can get/set values from the store during execution.
-
+        logger: Logger or True, None
+            A python logger that can provide traceback information on errors when running apps; if True, uses streamlit's logger
+        log_level: str, 'WARNING'
+            A string to set the logging level; only matters if you set the logger parameter
         """
 
         self._apps = {}
@@ -120,8 +127,11 @@ def __init__(self,
         self._guest_access = 1
         self._hydralit_url_hash='hYDRALIT|-HaShing==seCr8t'
         self._no_access_level = 0
-
         self._user_session_params = session_params
+        self._logger = get_logger(__name__) if logger is True else logger
+
+        log_level_mapping = {'CRITICAL':50, 'ERROR':40, 'WARNING':30, 'INFO':20, 'DEBUG':10, 'NOTSET':0}
+        self._log_level = log_level_mapping[log_level.upper()]
 
         try:
             st.set_page_config(page_title=title,page_icon=favicon,layout=layout,initial_sidebar_state=sidebar_state,)
@@ -281,6 +291,9 @@ def _run_selected(self):
         except Exception as e:
             st.error('😭 Error triggered from app: **{}**'.format(self.session_state.selected_app))
             st.error('Details: {}'.format(e))
+            if self._logger:
+                self._logger.log(level=self._log_level, msg=e)
+                self._logger.log(level=self._log_level, msg=traceback.format_exc())
 
 
     def _clear_session_values(self):