pass exception information to javascript for possible handling

Author: krpatter-intc

eel/__init__.py

@@ -1,5 +1,6 @@
 from __future__ import print_function   # Python 2 compatibility stuff
 from builtins import range
+import traceback
 from io import open
 
 import gevent as gvt
@@ -254,9 +255,21 @@ def _repeated_send(ws, msg):
 
 def _process_message(message, ws):
     if 'call' in message:
-        return_val = _exposed_functions[message['name']](*message['args'])
+        error_info = {}
+        try:
+            return_val = _exposed_functions[message['name']](*message['args'])
+            status = 'ok'
+        except Exception as e:
+            err_traceback = traceback.format_exc()
+            traceback.print_exc()
+            return_val = None
+            status = 'error'
+            error_info['errorText'] = repr(e)
+            error_info['errorTraceback'] = err_traceback
         _repeated_send(ws, _safe_json({ 'return': message['call'],
-                                        'value': return_val  }))
+                                        'status': status,
+                                        'value': return_val,
+                                        'error': error_info,}))
     elif 'return' in message:
         call_id = message['return']
         if call_id in _call_return_callbacks:

eel/eel.js

@@ -76,10 +76,10 @@ eel = {
     _call_return: function(call) {
         return function(callback = null) {
             if(callback != null) {
-                eel._call_return_callbacks[call.call] = callback;
+                eel._call_return_callbacks[call.call] = {resolve: callback};
             } else {
-                return new Promise(function(resolve) {
-                    eel._call_return_callbacks[call.call] = resolve;
+                return new Promise(function(resolve, reject) {
+                    eel._call_return_callbacks[call.call] = {resolve: resolve, reject: reject};
                 });
             }
         }
@@ -137,7 +137,12 @@ eel = {
                 } else if(message.hasOwnProperty('return')) {
                     // Python returning a value to us
                     if(message['return'] in eel._call_return_callbacks) {
-                        eel._call_return_callbacks[message['return']](message.value);
+                        if(message['status']==='ok'){
+                            eel._call_return_callbacks[message['return']].resolve(message.value);
+                        }
+                        else if(message['status']==='error' &&  eel._call_return_callbacks[message['return']].reject) {
+                                eel._call_return_callbacks[message['return']].reject(message['error']);
+                        }
                     }
                 } else {
                     throw 'Invalid message ' + message;
@@ -146,7 +151,7 @@ eel = {
             };
         });
     }
-}
+};
 
 eel._init();