Merge a series of JSON documents

This Python module allows you to merge a series of JSON documents into a single one. A trivial example of this would be:

Document A:

{
    "foo": 1
}

Document B:

{
    "bar": 2
}

Result of the merge:

{
    "foo": 1,
    "bar": 2,
}

Real life documents typically involve more complicated merge operations. For example, what happens when both A and B contain a foo property? Are arrays in the document appended, replaced or merged item-by-item?

jsonmerge allows you to specify merge strategies for each object, array and value in the document. The specification is based on JSON Schema. On each level of the hierarchy, the mergeStrategy keyword specifies the merge strategy used for that instance.

Module content

The module exports a Merger class:

>>> from jsonmerge import Merger

# load schema document
>>> schema = {}
>>> merger = Merger(schema)

# start with an empty base document
>>> base = None

# load version 1 of the document and merge it into base)
>>> v1 = {'foo': 1}
>>> base = merger.merge(base, v1)

# load version 2 of the document and merge it into base)
>>> v2 = {'bar': 2}
>>> base = merger.merge(base, v2)

>>> base
{'foo': 1, 'bar': 2}

Merge strategies

These are the currently implemented merge strategies. Here base refers to the old document you are merging changes into and head refers to the newer document.

overwrite

Overwrite with the value in base with value in head. Works with any type.

append

Append arrays. Works only with arrays.

objectMerge

Merge objects. Resulting objects have properties from both base and head. Any properties that are present both in base and head are merged based on the strategy specified further down in the hierarchy (e.g. in properties, patternProperties or additionalProperties schema keywords).

version

Changes the type of the value to an array. New values are appended to the array in the form of an object with a value property. This way all values seen during the merge are preserved.

versionLast

Same as version, except only the last version is preserved.

If a merge strategy is not specified in the schema, objectMerge is used to objects and overwrite for all other values.

Requirements

You need jsonschema (https://pypi.python.org/pypi/jsonschema) module installed.

Installation

You install Unidecode, as you would install any Python module, by running these commands:

python setup.py install
python setup.py test

Source

The latest version is available on GitHub: https://github.com/avian2/jsonmerge

License

Copyright 2014, Tomaz Solc <tomaz.solc@tablix.org>

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.