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Description
Python 3.9.18, jsonpatch 1.33
I came across an issue where sometimes the order of the created patch operations is wrong:
src_obj = {'a': [{'id': [1]}, {'id': [2]}], 'b': [{'id': 5}]}
tgt_obj = {'a': [{'id': []}, {'id': [1]}], 'b': [{'id': 5, 'newKey': 2}]}
patch = jsonpatch.make_patch(src_obj, tgt_obj)
print(patch)The correct patch is (of course, using a combination of adds and removes would also work, but it seems jsonpatch prefers moves):
[
{"op": "move", "from": "/a/1/id/0", "path": "/b/0/newKey"},
{"op": "move", "from": "/a/0/id/0", "path": "/a/1/id/0"}
]
However, sometimes the patch is created in the reverse order, which because the operations are "chained" results in a wrongly-modified target object.
Reproduce (patch_test.py):
import jsonpatch
src_obj = {'a': [{'id': [1]}, {'id': [2]}], 'b': [{'id': 5}]}
tgt_obj = {'a': [{'id': []}, {'id': [1]}], 'b': [{'id': 5, 'newKey': 2}]}
patch = jsonpatch.make_patch(src_obj, tgt_obj)
print(patch)
# Check normal application of the patch
tgt_obj_check = jsonpatch.apply_patch(src_obj, patch)
print('Forward', 'OK' if len(jsonpatch.make_patch(tgt_obj, tgt_obj_check).patch) == 0 else 'ERROR', '->', tgt_obj_check)
# Check reverse application of the patch
tgt_obj_check = jsonpatch.apply_patch(src_obj, patch.patch[::-1])
print('Reverse', 'OK' if len(jsonpatch.make_patch(tgt_obj, tgt_obj_check).patch) == 0 else 'ERROR', '->', tgt_obj_check)Running the script several times (note that the results are random, so probably related to some internal Python hash):
>> python patch_test.py
[{"op": "move", "from": "/a/1/id/0", "path": "/b/0/newKey"}, {"op": "move", "from": "/a/0/id/0", "path": "/a/1/id/0"}]
Forward OK -> {'a': [{'id': []}, {'id': [1]}], 'b': [{'id': 5, 'newKey': 2}]}
Reverse ERROR -> {'a': [{'id': []}, {'id': [2]}], 'b': [{'id': 5, 'newKey': 1}]}
>> python patch_test.py
[{"op": "move", "from": "/a/0/id/0", "path": "/a/1/id/0"}, {"op": "move", "from": "/a/1/id/0", "path": "/b/0/newKey"}]
Forward ERROR -> {'a': [{'id': []}, {'id': [2]}], 'b': [{'id': 5, 'newKey': 1}]}
Reverse OK -> {'a': [{'id': []}, {'id': [1]}], 'b': [{'id': 5, 'newKey': 2}]}
>> python patch_test.py
[{"op": "move", "from": "/a/0/id/0", "path": "/a/1/id/0"}, {"op": "move", "from": "/a/1/id/0", "path": "/b/0/newKey"}]
Forward ERROR -> {'a': [{'id': []}, {'id': [2]}], 'b': [{'id': 5, 'newKey': 1}]}
Reverse OK -> {'a': [{'id': []}, {'id': [1]}], 'b': [{'id': 5, 'newKey': 2}]}
>> python patch_test.py
[{"op": "move", "from": "/a/0/id/0", "path": "/a/1/id/0"}, {"op": "move", "from": "/a/1/id/0", "path": "/b/0/newKey"}]
Forward ERROR -> {'a': [{'id': []}, {'id': [2]}], 'b': [{'id': 5, 'newKey': 1}]}
Reverse OK -> {'a': [{'id': []}, {'id': [1]}], 'b': [{'id': 5, 'newKey': 2}]}
>> python patch_test.py
[{"op": "move", "from": "/a/0/id/0", "path": "/a/1/id/0"}, {"op": "move", "from": "/a/1/id/0", "path": "/b/0/newKey"}]
Forward ERROR -> {'a': [{'id': []}, {'id': [2]}], 'b': [{'id': 5, 'newKey': 1}]}
Reverse OK -> {'a': [{'id': []}, {'id': [1]}], 'b': [{'id': 5, 'newKey': 2}]}
>> python patch_test.py
[{"op": "move", "from": "/a/0/id/0", "path": "/a/1/id/0"}, {"op": "move", "from": "/a/1/id/0", "path": "/b/0/newKey"}]
Forward ERROR -> {'a': [{'id': []}, {'id': [2]}], 'b': [{'id': 5, 'newKey': 1}]}
Reverse OK -> {'a': [{'id': []}, {'id': [1]}], 'b': [{'id': 5, 'newKey': 2}]}
>> python patch_test.py
[{"op": "move", "from": "/a/1/id/0", "path": "/b/0/newKey"}, {"op": "move", "from": "/a/0/id/0", "path": "/a/1/id/0"}]
Forward OK -> {'a': [{'id': []}, {'id': [1]}], 'b': [{'id': 5, 'newKey': 2}]}
Reverse ERROR -> {'a': [{'id': []}, {'id': [2]}], 'b': [{'id': 5, 'newKey': 1}]}
>> python patch_test.py
[{"op": "move", "from": "/a/1/id/0", "path": "/b/0/newKey"}, {"op": "move", "from": "/a/0/id/0", "path": "/a/1/id/0"}]
Forward OK -> {'a': [{'id': []}, {'id': [1]}], 'b': [{'id': 5, 'newKey': 2}]}
Reverse ERROR -> {'a': [{'id': []}, {'id': [2]}], 'b': [{'id': 5, 'newKey': 1}]}
>> python patch_test.py
[{"op": "move", "from": "/a/1/id/0", "path": "/b/0/newKey"}, {"op": "move", "from": "/a/0/id/0", "path": "/a/1/id/0"}]
Forward OK -> {'a': [{'id': []}, {'id': [1]}], 'b': [{'id': 5, 'newKey': 2}]}
Reverse ERROR -> {'a': [{'id': []}, {'id': [2]}], 'b': [{'id': 5, 'newKey': 1}]}
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