Pull requests are welcome, forking from the master branch. If you are new to GitHub, be sure and check out GitHub’s Hello World tutorial.

Environment Setup

You’ll need a python3 installation and a virtualenv. There are many ways to manage virtualenvs, but a minimal example is shown below.

$ virtualenv -p python3 venv && source venv/bin/activate
$ pip install -e .[signals] -r requirements-dev.txt

A java runtime is required to run the integration tests. After installing java, download and untar the mock dynamodb server like so:

$ wget --quiet -O /tmp/dynamodb_local_latest.tar.gz
$ tar -xzf /tmp/dynamodb_local_latest.tar.gz -C /tmp

Note that you may want to place files somewhere other than /tmp.

Running Tests

After installing requirements in environment setup and ensuring your venv is activated, unit tests are run with:

$ pytest tests/ -k "not ddblocal"

There are also a set of integration tests that require a local dynamodb server to be mocked.

$ java -Djava.library.path=/tmp/DynamoDBLocal_lib -jar /tmp/DynamoDBLocal.jar -inMemory -port 8000
$ pytest tests/      # in another window

Backwards Compatibility

Particular care should be paid to backwards compatibility when making any change in PynamoDB, especially with attributes and serialization/deserialization. Consider data written with an older version of the library and whether it can still be read after upgrading.

Where possible, write logic to continue supporting older data for at least one major version to simplify the upgrade path. Where that’s not possible, create a new version of the attribute with a different name and mark the old one as deprecated.

Outside of data compatibility, follow the usual semver rules for API changes and limit breaking changes to a major release.

Pull Requests

Pull requests should:

  1. Specify an accurate title and detailed description of the change
  2. Include thorough testing. Unit tests at a minimum, sometimes integration tests
  3. Add test coverage for new code (CI will verify the delta)
  4. Add type annotations to any code modified
  5. Write documentation for new features
  6. Maintain the existing code style (mostly PEP8) and patterns


Any non-trivial change should be documented in the release notes. Please include sufficient detail in the PR description, which will be used by maintainers to populate the release notes.


Docs are built using sphinx and available on readthedocs. A release of the latest tag (tracking master) happens automatically on merge via a Github webhook.