Contributing

Contributions from the community are essential in keeping Hibernate (and any Open Source project really) strong and successful.

Legal

All original contributions to Hibernate are licensed under the Apache License version 2.0 (Apache-2.0), or, if another license is specified as governing the file or directory being modified, such other license. The Apache-2.0 license text is included verbatim in the LICENSE.txt file

Note that Hibernate ORM 7.0.0.Beta4 and earlier are distributed under a different license. To allow for potential backporting, the Hibernate team asks contributors to dual-license their contribution. A Pull Request template already applies the proper wording to make it easy.

All contributions are subject to the Developer Certificate of Origin (DCO).

The DCO text is available verbatim in the dco.txt file in the root directory of the ORM repository.

Guidelines

While we try to keep requirements for contributing to a minimum, there are a few guidelines we ask that you mind.

For code contributions, these guidelines include:

Respect the project code style - find templates for IntelliJ IDEA or Eclipse
Have a corresponding JIRA issue and be sure to include the key for this JIRA issue in your commit messages.
Have a set of appropriate tests.
For your convenience, a set of test templates have been made available.

When submitting bug reports, the tests should reproduce the initially reported bug and illustrate that your solution addresses the issue. For features/enhancements, the tests should demonstrate that the feature works as intended.
In both cases, be sure to incorporate your tests into the project to protect against possible regressions.
If applicable, documentation should be updated to reflect the introduced changes
The code compiles and the tests pass (./gradlew clean build)

For documentation contributions, mainly to respect the project code style, especially in regards to the use of tabs - as mentioned above, code style templates are available for both IntelliJ IDEA and Eclipse IDEs. Ideally, these contributions would also have a corresponding JIRA issue, although this is less necessary for documentation contributions.

Getting Started

If you are just getting started with Git, GitHub, and/or contributing to Hibernate via GitHub there are a few pre-requisite steps to follow:

Make sure you have a Hibernate JIRA account
Make sure you have a GitHub account
Fork the Hibernate repository. As discussed in the linked page, this also includes:
- set up your local git install
- clone your fork
Instruct git to ignore certain commits when using git blame. From the directory of your local clone, run this: git config blame.ignoreRevsFile .git-blame-ignore-revs
See the wiki pages for setting up your IDE, whether you use IntelliJ IDEA or Eclipse⁽¹⁾.

Create the working (topic) branch

Create a topic branch on which you will work. The convention is to incorporate the JIRA issue key in the name of this branch, although this is more of a mnemonic strategy than a hard-and-fast rule - but doing so helps:

Remember what each branch is for
Isolate the work from other contributions you may be working on

If there is not already a JIRA issue covering the work you want to do, create one.

Assuming you will be working from the main branch and working on the JIRA HHH-123 : git checkout -b HHH-123 main

Code

Do your thing!

Commit

Make commits of logical units
Be sure to start each commit message using the JIRA issue key, this is how JIRA will pick up the related commits and display them on the JIRA issue
Make sure you have added the necessary tests for your changes
Run all the tests to ensure nothing else was accidentally broken

Before committing, if you want to pull in the latest upstream changes (highly appreciated btw), please use rebasing rather than merging. Merging creates "merge commits" that invariably muck up the project timeline.

Submit

Push your changes to the topic branch in your fork of the repository
Initiate a pull request
Once your pull request has been submitted you can verify that the pull request has been properly linked to its corresponding Jira issue by confirming that the issue status is now Waiting for Review and that clicking on the Recent rule runs Refresh button on the right side of the issue displays a Pull Request (ORM) entry.

It is important that this topic branch of your fork:

Is isolated to just the work on this one JIRA issue, or multiple issues if they are related and also fixed/implemented by this work. The main point is to not push commits for more than one PR to a single branch - GitHub PRs are linked to a branch rather than specific commits
remain until the PR is closed. Once the underlying branch is deleted the corresponding PR will be closed, if not already, and the changes will be lost

Notes

⁽¹⁾ Gradle eclipse plugin is no longer supported, so the recommended way to import the project in your IDE is with the proper IDE tools/plugins. Don't try to run ./gradlew clean eclipse --refresh-dependencies from the command line as you'll get an error because eclipse no longer exists