fix non exists key cause exception

Author: wangjild

jsonpath_rw/jsonpath.py

@@ -525,7 +525,7 @@ def update(self, data, val):
 
     def exclude(self, data):
         for field in self.reified_fields(DatumInContext.wrap(data)):
-            if field in data:
+            if data and field in data:
                 del data[field]
         return data
 

tests/test_jsonpath.py

@@ -1,5 +1,6 @@
 from __future__ import unicode_literals, print_function, absolute_import, division, generators, nested_scopes
 import unittest
+import json
 
 from jsonpath_rw import jsonpath # For setting the global auto_id_field flag
 
@@ -71,8 +72,6 @@ def test_DatumInContext_in_context(self):
     #     assert AutoIdForDatum(DatumInContext(value=3, path=Fields('foo')),
     #                           id_field='id',
     #                           context=DatumInContext(value={'id': 'bizzle'}, path=This())).pseudopath == Fields('bizzle').child(Fields('foo'))
-                              
-                              
 
 class TestJsonPath(unittest.TestCase):
     """
@@ -526,6 +525,25 @@ def test_include_child(self):
             ({'foo': {'bar': 1, 'baz': 2}}, 'non', {}),
         ])
 
+    def test_exclude_not_exists(self):
+        self.check_exclude_cases([
+            (
+                {
+                    'foo': [
+                        {'bar': 'bar'},
+                        {'baz': None}
+                    ]
+                },
+                'foo.[*].baz.not_exist_key',
+                {
+                    'foo': [
+                        {'bar': 'bar'},
+                        {'baz': None}
+                    ]
+                },
+             ),
+        ])
+
     """
     def test_include_where(self):
         self.check_include_cases([