simplepath

simplepath is a library for data-structure lookups using super simple expressions with performance in mind. "simplepath" is a word play on some other *path technologies such as xpath, jsonpath, jpath, etc.

• Free software: MIT license
• GitHub: https://github.com/dealertrack/simplepath

Inspiration

The inspiration for simplepath was performance. Many other libraries focus on making single lookups, however they fall short when a lot of data needs to be queried.

For example if a dictionary with some structure needs to be converted into another dictionary with a different structure, a simple and configurable way of doing that might be to define a configuration dictionary where the keys will be the keys of the output dictionary, and values will be lookup expressions to get appropriate data:

{
    "greetings": "foo.greeting",
    "planet": "foo.[0].planet",
    ...
}

The above approach is easy to implement, however is not very performant since for each lookup the lookup expression will have to be evaluated. At dealertrack, we needed to do something similar at some point and tried jsonpath-rw which would sometimes take 15 seconds to map dictionaries with only a couple hundred expressions. Upon some investigation, most of the time was being spent in ply. Unfortunately we did not find another comparable library which accomplished everything we needed, and satisfied our performance requirements, so simplepath was born.

Installing

You can install simplepath using pip:

$ pip install simplepath

Quick Guide

Here is a quick example.

from simplepath.mapper import Mapper

class MyMapper(Mapper):
    config = {
        'greetings': 'example.greetings',
        'to': 'example.planets.<find:planet=Earth>.residents',
    }

data = {
    'example': {
        'greetings': 'Hello',
        'planets': [
            {
                'planet': 'Mars',
                'residents': 'martians',
            },
            {
                'planet': 'Earth',
                'residents': 'people',
            },
            {
                'planet': 'Space',
                'residents': 'aliens',
            },
        ]
    }
}

MyMapper.map_data(data) == {
    'greetings': 'Hello',
    'to': 'people',
}

Testing

To run the tests you need to install testing requirements first:

$ make install

Then to run tests, you can use nosetests or simply use Makefile command:

$ nosetests -sv
# or
$ make test