protean 0.15.0

Protean Application Framework

Protean

Protean is an opinionated and pragmatic framework for building event-driven applications using the CQRS pattern.

Installation

Protean is available on PyPI:

$ pip install protean

Protean officially supports Python 3.11+.

Quick Start

from protean import Domain
from protean.fields import String, Text

domain = Domain(name="Publishing")

@domain.aggregate
class Post:
    title: String(required=True, max_length=1000)
    slug: String(required=True, max_length=1024)
    content: Text(required=True)

domain.init()
with domain.domain_context():
    post = Post(
        title="Hello World",
        slug="hello-world",
        content="Lorem Ipsum ..."
    )

    domain.repository_for(Post).add(post)

Documentation

Online docs are available at https://docs.proteanhq.com.

Quality

Protean is tested against 5 backing services across 4 Python versions on every commit.

Metric	Value
Tests	3,826 (3.5:1 test-to-code ratio)
Linting	Zero violations (Ruff)
Complexity	Avg 2.97 cyclomatic (A grade)
Maintainability	A rank (97% of files)
CI Matrix	Python 3.11-3.14 x PostgreSQL, Redis, Elasticsearch, MessageDB, MSSQL

See the full Quality Report for details.

Contributing

Note: Protean framework is not associated or related to Protean eGov Technologies or Code for Gov Tech initiatives.

1. Check for open issues or open a fresh issue to start a discussion around a feature idea or a bug.
2. Fork the repository on GitHub, branch off main and start making your changes.
3. Write a test which shows that the bug was fixed or that the feature works as expected.
4. Send a pull request and bug the maintainer until it gets merged and published.

For more information, please check out the community section.

License

BSD 3-Clause License

Copyright (c) 2018-2026, Subhash Bhushan C. All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

• Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.

• Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

• Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.