onedict

A Python library for recursively merging dictionaries with customizable conflict resolution strategies

What is onedict?

onedict is a Python library that provides a simple way to merge multiple dictionaries with customizable conflict resolution strategies. It allows you to merge dictionaries with nested structures and provides built-in solvers for common conflict resolution strategies.

Installation

pip install onedict

Usage

Basic Usage

To merge two or more dictionaries:

from onedict.merger import merge

dict1 = {"info": {"version": "1.0.0", "author": "Alice"}}
dict2 = {"info": {"license": "MIT"}, "data": {"value": 42}}

merged = merge(dict1, dict2)  # More dictionaries can be added as arguments
print(merged)
# Output: {'info': {'version': '1.0.0', 'author': 'Alice', 'license': 'MIT'}, 'data': {'value': 42}}

Handling Conflicts

When merging dictionaries, conflicts may arise when two dictionaries have the same key with different values. By default, a MergeConflictError exception is raised when a conflict is detected:

from onedict.merger import merge, MergeConflictError

dict1 = {"foo": "bar"}
dict2 = {"foo": "baz"}

try:
    merged = merge(dict1, dict2)   # Raises MergeConflictError
except MergeConflictError as e:
    print(e)

To handle conflicts, you can provide a list of conflict solvers to the merge function:

def custom_solver(keys, value1, value2):
    return value1  # Keep the value from the first dictionary

merged = merge(dict1, dict2, conflict_solvers=[custom_solver])
print(merged)  # Output: {'foo': 'bar'}

Conflict solvers are added to the conflict_solvers list in the order they are provided. The first solver that returns a non-Skip value is used to resolve the conflict. If none of the solvers can resolve the conflict, a MergeConflictError is raised.

Built-in Solvers

onedict provides built-in solvers for common conflict resolution strategies:

from onedict.merger import merge
from onedict.solvers import unique_lists

merged = merge(
    {"foo": ["bar", "baz"]},
    {"foo": ["bar", "qux"]},
    conflict_solvers=[unique_lists]
)
print(merged)  # Output: {'foo': ['bar', 'baz', 'qux']}

The following built-in solvers are available:

Solver Name	Description
unique_lists	Merges lists by combining unique elements from both lists.
concatenate_strings	Merges two strings by concatenating them with a separator.
keep_original	Keeps the original value and discards the new one.
keep_new	Keeps the new value and discards the original one.

Custom Conflict Solvers

You can create custom conflict solvers to handle specific types of conflicts:

from onedict.merger import merge, Skip

def adder(keys, value1, value2):
    if isinstance(value1, int) and isinstance(value2, int):
        return value1 + value2
    return Skip()

merged = merge(
    {"foo": 1},
    {"foo": 2},
    conflict_solvers=[adder]
)
print(merged)  # Output: {'foo': 3}