Made change to diff near line 1128 to change evaluations for lengths …

…from >1 to >0

deepdiff/diff.py

@@ -1125,7 +1125,9 @@ def defaultdict_orderedset():
             pre_calced_distances = self._precalculate_numpy_arrays_distance(
                 hashes_added, hashes_removed, t1_hashtable, t2_hashtable, _original_type)
 
-        if hashes_added and hashes_removed and self.iterable_compare_func and len(hashes_added) > 1 and len(hashes_removed) > 1:
+        if hashes_added and hashes_removed \
+                and self.iterable_compare_func \
+                and len(hashes_added) > 0 and len(hashes_removed) > 0:
             pre_calced_distances = self._precalculate_distance_by_custom_compare_func(
                 hashes_added, hashes_removed, t1_hashtable, t2_hashtable, _original_type)
 

tests/test_ignore_order.py

@@ -1072,6 +1072,121 @@ def compare_func(x, y, level=None):
         assert expected_with_compare_func == ddiff2
         assert ddiff != ddiff2
 
+    def test_ignore_order_with_compare_func_with_one_each_hashes_added_hashes_removed(self):
+        """
+        Scenario:
+        In this example which demonstrates the problem... We have two dictionaries containing lists for
+        individualNames.  Each list contains exactly 2 elements. The effective change is that we are
+        replacing the 2nd element in the list.
+        NOTE: This is considered a REPLACEMENT of the second element and not an UPDATE of the element
+        because we are providing a custom compare_func which will determine matching elements based on
+        the value of the nameIdentifier field.  If the custom compare_func is not used, then
+        deepdiff.diff will mistakenly treat the difference as being individual field updates for every
+        field in the second element of the list.
+
+        Intent:
+        Use our custom compare_func, since we have provided it.
+        We need to fall into self._precalculate_distance_by_custom_compare_func
+        To do this, we are proposing a change to deepdiff.diff line 1128:
+
+        Original:
+            if hashes_added and hashes_removed and self.iterable_compare_func and len(hashes_added) > 1 and len(hashes_removed) > 1:
+
+        Proposed/Updated:
+            if hashes_added and hashes_removed \
+            and self.iterable_compare_func \
+            and len(hashes_added) > 0 and len(hashes_removed) > 0:
+
+        NOTE: It is worth mentioning that deepdiff.diff line 1121, might also benefit by changing the length conditions
+        to evaluate for > 0 (rather than > 1).
+        """
+
+        t1 = {
+            "individualNames": [
+                {
+                    "firstName": "Johnathan",
+                    "lastName": "Doe",
+                    "prefix": "COLONEL",
+                    "middleName": "A",
+                    "primaryIndicator": True,
+                    "professionalDesignation": "PHD",
+                    "suffix": "SR",
+                    "nameIdentifier": "00001"
+                },
+                {
+                    "firstName": "John",
+                    "lastName": "Doe",
+                    "prefix": "",
+                    "middleName": "",
+                    "primaryIndicator": False,
+                    "professionalDesignation": "",
+                    "suffix": "SR",
+                    "nameIdentifier": "00002"
+                }
+            ]
+        }
+
+        t2 = {
+            "individualNames": [
+                {
+                    "firstName": "Johnathan",
+                    "lastName": "Doe",
+                    "prefix": "COLONEL",
+                    "middleName": "A",
+                    "primaryIndicator": True,
+                    "professionalDesignation": "PHD",
+                    "suffix": "SR",
+                    "nameIdentifier": "00001"
+                },
+                {
+                    "firstName": "Johnny",
+                    "lastName": "Doe",
+                    "prefix": "",
+                    "middleName": "A",
+                    "primaryIndicator": False,
+                    "professionalDesignation": "",
+                    "suffix": "SR",
+                    "nameIdentifier": "00003"
+                }
+            ]
+        }
+        def compare_func(item1, item2, level=None):
+            print("*** inside compare ***")
+            it1_keys = item1.keys()
+
+            try:
+
+                # --- individualNames ---
+                if 'nameIdentifier' in it1_keys and 'lastName' in it1_keys:
+                    match_result = item1['nameIdentifier'] == item2['nameIdentifier']
+                    print("individualNames - matching result:", match_result)
+                    return match_result
+                else:
+                    print("Unknown list item...", "matching result:", item1 == item2)
+                    return item1 == item2
+            except Exception:
+                raise CannotCompare() from None
+        # ---------------------------- End of nested function
+
+        actual_diff = DeepDiff(t1, t2, report_repetition=True,
+                             ignore_order=True, iterable_compare_func=compare_func, cutoff_intersection_for_pairs=1)
+
+        old_invalid_diff = {
+            'values_changed': {"root['individualNames'][1]['firstName']": {'new_value': 'Johnny', 'old_value': 'John'},
+                               "root['individualNames'][1]['middleName']": {'new_value': 'A', 'old_value': ''},
+                               "root['individualNames'][1]['nameIdentifier']": {'new_value': '00003',
+                                                                                'old_value': '00002'}}}
+        new_expected_diff = {'iterable_item_added': {
+            "root['individualNames'][1]": {'firstName': 'Johnny', 'lastName': 'Doe', 'prefix': '', 'middleName': 'A',
+                                           'primaryIndicator': False, 'professionalDesignation': '', 'suffix': 'SR',
+                                           'nameIdentifier': '00003'}}, 'iterable_item_removed': {
+            "root['individualNames'][1]": {'firstName': 'John', 'lastName': 'Doe', 'prefix': '', 'middleName': '',
+                                           'primaryIndicator': False, 'professionalDesignation': '', 'suffix': 'SR',
+                                           'nameIdentifier': '00002'}}}
+
+        assert old_invalid_diff != actual_diff
+        assert new_expected_diff == actual_diff
+
 
 class TestDynamicIgnoreOrder:
     def test_ignore_order_func(self):