Deepmerge: merging nested data structures

Deepmerge is a flexible library to handle merging of nested data structures in Python (e.g. lists, dicts).

It is available on pypi, and can be installed via pip:

pip install deepmerge


Generic Strategy

from deepmerge import always_merger

base = {"foo": ["bar"]}
next = {"foo": ["baz"]}

expected_result = {'foo': ['bar', 'baz']}
result = always_merger.merge(base, next)

assert expected_result == result

Custom Strategy

from deepmerge import Merger

my_merger = Merger(
    # pass in a list of tuple, with the
    # strategies you are looking to apply
    # to each type.
        (list, ["append"]),
        (dict, ["merge"])
    # next, choose the fallback strategies,
    # applied to all other types:
    # finally, choose the strategies in
    # the case where the types conflict:
base = {"foo": ["bar"]}
next = {"bar": "baz"}
my_merger.merge(base, next)
assert base == {"foo": ["bar"], "bar": "baz"}

Want to get started? see the User Guide


Indices and tables