dictdiffer

library0.10.0pypypi✓ verified 26d ago

Dictdiffer is a Python library designed to compute differences between dictionaries and apply patches based on those differences. It handles nested structures, lists, and sets. The current version is 0.9.0, with releases occurring on an as-needed basis.

serialization data

pip install dictdiffer

github ↗package ↗docs ↗changelog ↗

INSTALL

IMPORT

SIG · DICTDIFFER

dictdiffer

serializationpythonv0.10.0

Install

1.6s avg

Import

10ms

Disk

16MB

Pass rate

10/ 10

Env Coverage10 / 10

glibc

3.9–3.13

musl

3.9–3.13

Install & Compatibility

Where this runs

tested against v0.10.0 · pip install

no network on importno background threads

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

py 3.10–3.95 runs

installs and imports cleanly · install 0.0s · import 0.002s · 17.9MB

glibc

py 3.10–3.95 runs

installs and imports cleanly · install 1.6s · import 0.004s · 18MB

16MB installed

● package 16MB

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

diff

✓ from dictdiffer import diff

patch

✓ from dictdiffer import patch

revert

✓ from dictdiffer import revert

swap

✓ from dictdiffer import swap

DictDiffer

✓ from dictdiffer import DictDiffer

Use this class for more configurable diffing, e.g., ignoring specific keys.

This quickstart demonstrates how to use `diff` to find differences between two dictionaries, `patch` to apply those changes, and `revert` to undo them. It also shows a basic example of ignoring specific keys during diffing.

from dictdiffer import diff, patch, revert # Example dictionaries old = {'a': 1, 'b': {'c': 2, 'd': [3, 4]}} new = {'a': 10, 'b': {'c': 2, 'd': [3, 5]}, 'e': 6} # Compute the diff delta = list(diff(old, new)) print(f"Diff operations: {delta}") # Apply the patch to the old dictionary patched_dict = patch(delta, old) print(f"Patched dictionary: {patched_dict}") # Revert the patch from the new dictionary reverted_dict = revert(delta, new) print(f"Reverted dictionary: {reverted_dict}") # Example with ignoring keys old_ignore = {'name': 'Alice', 'version': '1.0', 'data': [1,2]} new_ignore = {'name': 'Alice', 'version': '1.1', 'data': [1,2]} ignored_delta = list(diff(old_ignore, new_ignore, ignore=['version'])) print(f"Diff ignoring 'version': {ignored_delta}")

Debug

Known issues

breakingDictdiffer v0.9.0 dropped support for Python versions older than 3.5. Ensure your environment meets this minimum requirement when upgrading.

fix

Upgrade to Python 3.5 or newer, or pin `dictdiffer` to a version <0.9.0 if Python 2.x/3.4 compatibility is required (though not recommended).

affects: <0.9.0

breakingIn v0.7.0, `dictdiffer` started using `deepcopy` internally for all diff operations to prevent results from referencing parts of the original structures. This change ensures that diff objects are immutable and do not change if the original dictionaries are modified later, but it alters previous behavior where direct references might have existed.

fix

Review existing code that processes diff outputs from versions prior to 0.7.0 to ensure it correctly handles the new immutable behavior. This is generally a safer approach, but could break code relying on mutable references.

affects: <0.7.0

gotchaPrior to v0.7.1, dictionary keys containing dots (`.`) could cause unexpected behavior or errors during diff operations. While fixed in v0.7.1, users on older versions should be aware of this limitation.

fix

Upgrade `dictdiffer` to version 0.7.1 or newer to correctly handle keys with dots.

affects: <0.7.1

gotchaVersions prior to v0.8.1 contained a bug that could lead to invalid diff output when comparing sets. This resulted in incorrect patch instructions for set differences.

fix

Upgrade `dictdiffer` to version 0.8.1 or newer to ensure correct diffing and patching of set elements.

affects: <0.8.1

Errors

Common errors & fixes

ModuleNotFoundError: No module named 'dictdiffer'

The `dictdiffer` library has not been installed in your Python environment.

fix

pip install dictdiffer

NameError: name 'diff' is not defined

The `diff` function was called without being properly imported from the `dictdiffer` library.

fix

from dictdiffer import diff, patch, swap, revert

TypeError: unhashable type: 'list'

This error occurs when attempting to use Python's built-in set operations to compare dictionaries that contain unhashable types like lists, which `dictdiffer` is designed to handle.

fix

Use `dictdiffer.diff()` directly, as it correctly handles nested lists and other unhashable types. Example: `from dictdiffer import diff; differences = list(diff(dict1, dict2))`

KeyError: index out of bounds on patch

This error typically arises when attempting to `patch` a dictionary, especially with differences involving lists, where the patch instructions refer to an index that no longer exists in the destination list, often due to prior modifications or an inconsistent `diff_result`.

fix

Ensure the `diff_result` is applied to a destination dictionary that is consistent with the 'first' dictionary used to generate the diff, and that no intermediate changes have made list indices invalid. Verify the structure of the `diff_result` if manually generated.

Upgrade

Version history

0.10.0latest on PyPI · released Jul 16, 2026

Audit

Dependencies

No dependency data recorded yet.

Agent activity

12 hits · last 30 days

node

OpenAI (training)

Resources

githubhttps://github.com/inveniosoftware/dictdiffer ↗

packagehttps://pypi.org/project/dictdiffer/ ↗

docshttps://dictdiffer.rtfd.io/ ↗

changeloghttps://github.com/inveniosoftware/dictdiffer/blob/master/CHANGES ↗