Python RQL

Introduction

RQL (Resource query language) is designed for modern application development. It is built for the web, ready for NoSQL, and highly extensible with simple syntax. This is a query language fast and convenient database interaction. RQL was designed for use in URLs to request object-style data structures.

RQL Reference

Install

Python RQL can be installed from pypi.org using pip:

$ pip install lib-rql

Documentation

Python RQL documentation is hosted on the Read the Docs service.

Projects using Python RQL

Django RQL is the Django app, that adds RQL filtering to your application.

Visit the Django RQL project repository for more informations.

Notes

Parsing is done with Lark (cheatsheet). The current parsing algorithm is LALR(1) with standard lexer.

0. Values with whitespaces or special characters, like ',' need to have "" or ''
1. Supported date format is ISO8601: 2019-02-12
2. Supported datetime format is ISO8601: 2019-02-12T10:02:00 / 2019-02-12T10:02Z / 2019-02-12T10:02:00+03:00

Supported operators

1. Comparison (eq, ne, gt, ge, lt, le, like, ilike, search)
2. List (in, out)
3. Logical (and, or, not)
4. Constants (null(), empty())
5. Ordering (ordering)
6. Select (select)
7. Tuple (t)

Examples

Parsing a RQL query

from py_rql import parse
from py_rql.exceptions import RQLFilterError

try:
    tree = parse('eq(key,value)')
except RQLFilterError:
    pass

Filter a list of dictionaries

from py_rql.constants import FilterTypes
from py_rql.filter_cls import FilterClass


class BookFilter(FilterClass):
    FILTERS = [
        {
            'filter': 'title',
        },
        {
            'filter': 'author.name',
        },
        {
            'filter': 'status',
        },
        {
            'filter': 'pages',
            'type': FilterTypes.INT,
        },
        {
            'filter': 'featured',
            'type': FilterTypes.BOOLEAN,
        },
        {
            'filter': 'publish_date',
            'type': FilterTypes.DATETIME,
        },
    ]

filters = BookFilter()

query = 'eq(title,Practical Modern JavaScript)'
results = list(filters.filter(query, DATA))

print(results)

query = 'or(eq(pages,472),lt(pages,400))'
results = list(filters.filter(query, DATA))

print(results)

Development

1. Python 3.8+
2. Install dependencies pip install poetry && poetry install

Testing

1. Python 3.8+
2. Install dependencies pip install poetry && poetry install

Check code style: poetry run flake8 Run tests: poetry run pytest

Tests reports are generated in tests/reports.

• out.xml - JUnit test results
• coverage.xml - Coverage xml results

To generate HTML coverage reports use: --cov-report html:tests/reports/cov_html

License

Python RQL is released under the Apache License Version 2.0.