Merge pull request kennknowles#33 from abloomston/nullObjs

Return empty result instead of crashing on index into None

Author: kennknowles

jsonpath_rw/jsonpath.py

@@ -477,7 +477,7 @@ class Index(JSONPath):
     JSONPath that matches indices of the current datum, or none if not large enough.
     Concrete syntax is brackets. 
 
-    WARNING: If the datum is not long enough, it will not crash but will not match anything.
+    WARNING: If the datum is None or not long enough, it will not crash but will not match anything.
     NOTE: For the concrete syntax of `[*]`, the abstract syntax is a Slice() with no parameters (equiv to `[:]`
     """
 
@@ -487,7 +487,7 @@ def __init__(self, index):
     def find(self, datum):
         datum = DatumInContext.wrap(datum)
 
-        if len(datum.value) > self.index:
+        if datum.value and len(datum.value) > self.index:
             return [DatumInContext(datum.value[self.index], path=self, context=datum)]
         else:
             return []

tests/test_jsonpath.py

@@ -130,7 +130,8 @@ def test_index_value(self):
         self.check_cases([
             ('[0]', [42], [42]),
             ('[5]', [42], []),
-            ('[2]', [34, 65, 29, 59], [29])
+            ('[2]', [34, 65, 29, 59], [29]),
+            ('[0]', None, [])
         ])
 
     def test_slice_value(self):