Version 5 supported

Contributing Code - Submitting Bugfixes and Enhancements

Silverstripe CMS will never be finished, and we need your help to keep making it better. If you're a developer a great way to get involved is to contribute patches to our modules and core codebase, fixing bugs or adding features.

The Silverstripe CMS core modules (framework and cms), as well as some of the more popular modules are in git version control. Silverstripe CMS hosts its modules on After installing git and creating a free account, you can "fork" a module, which creates a copy that you can commit to (see github's guide to "forking").

For other modules, our add-ons site lists the repository locations, typically using the version control system like "git".

If you are modifying CSS or JavaScript files in core modules, you'll need to regenerate some files. Please check out our client-side build tooling guide for details.

Note: By supplying code to the Silverstripe CMS core team in patches, tickets and pull requests, you agree to assign copyright of that code to Silverstripe Limited, on the condition that Silverstripe Limited releases that code under the BSD license.

We ask for this so that the ownership in the license is clear and unambiguous, and so that community involvement doesn't stop us from being able to continue supporting these projects. By releasing this code under a permissive license, this copyright assignment won't prevent you from using the code in any way you see fit.

Step-by-step: From forking to sending the pull request

Note: Please adjust the commands below to the version of Silverstripe CMS that you're targeting.
  1. Create a fork of the module you want to contribute to (listed on
  2. Install the project through composer. The process is described in detail in "Installation through Composer".

    composer create-project --keep-vcs silverstripe/installer ./your-website-folder 5.0.x-dev
  3. Add a new "upstream" remote to the module you want to contribute to (e.g. cms). This allows you to track the original repository for changes, and rebase/merge your fork as required. Use your Github user name for which you created the fork in Step 1.

    cd framework
    git remote rename origin upstream
    git branch --set-upstream-to upstream
    git remote add -f origin git://<your-github-user>/silverstripe-framework.git
  4. Branch for new issue and develop on issue branch

    # verify current branch 'base' then branch and switch
    cd framework
    git status
    git checkout -b <your-branch-name>
  5. As time passes, the upstream repository accumulates new commits. Keep your working copy's branch and issue branch up to date by periodically running a composer update. As a first step, make sure you have committed all your work, then temporarily switch over to the master branch while updating. Alternatively, you can use composer "repositories", but we've found that dramatically slows down any updates. You may need to resolve conflicts.

    cd framework && git checkout master
    composer update
    cd framework && git checkout <your-branch-name>
    cd framework && git rebase upstream/master
  6. When development is complete, run another update, and consider squashing your commits
  7. Push your branch to your GitHub fork

    cd framework
    git push origin <your-branch-name>
  8. Issue pull request on GitHub. Visit your forked repository on and click the "Create Pull Request" button next to the new branch.

Please read collaborating with pull requests on for more details.

The core team is then responsible for reviewing patches and deciding if they will make it into core. If there are any problems they will follow up with you, so please ensure they have a way to contact you!

Picking the right version

The Silverstripe CMS project follows the Semantic Versioning (SemVer) specification for releases. It clarifies what to expect from different releases, and also guides you in choosing the right branch to base your pull request on.

If you are unsure what branch your pull request should go to, consider asking in the GitHub issue that you address with your patch, or simply choose the "default branch" of the repository where you want to contribute to. That would usually target the next minor release of the module.

If you are changing existing APIs, introducing new APIs or major new features, please review our guidance on supported versions. You will need to choose the branch for your pull request accordingly.

As we follow SemVer, we name the branches in repositories accordingly (using BNF rules defined by

  • <positive digit> branches contain major versions and all changes for yet unreleased minor versions
  • <positive digit> "." <digits> branches contain released minor versions and all changes for yet to be released patch versions

Silverstripe CMS public APIs explicitly include:

  • namespaces, classes, interfaces and traits
  • public and protected scope (including methods, properties and constants)
  • global functions, variables
  • yml configuration file structure and value types
  • private static class properties (considered to be configuration variables)

Silverstripe CMS public APIs explicitly exclude:

  • private scope (methods and properties with the exception for private static)
  • entities marked as @internal
  • yml configuration file default values
  • HTML, CSS, JavaScript, TypeScript, SQL and anything else that is not PHP

Other entities might be considered to be included or excluded from the public APIs on case-by-case basis.

Any updates to third party dependencies in composer.json should aim to target the default branch for a minor release if possible. Targeting a patch release branch is acceptable if updating dependencies is required to fix a bug.

API from third party dependencies may indirectly be incorporated into Silverstripe CMS's API if:

  • they are defined as a parameter type for a supported method
  • they are defined as a return type for a supported method
  • they are extended by a Silverstripe CMS class.

When defining a return type or a parameter type, it is preferable to use a more generic interface rather than a specific class. Third party dependencies that are used for internal purposes and are not explicitly exposed via the Silverstripe CMS public API are not covered by SemVer and maybe substituted without notice.

The Pull Request Process

Once your pull request is issued, it's not the end of the road. A core committer will most likely have some questions for you and may ask you to make some changes depending on discussions you have. If you've been naughty and not adhered to the coding conventions, expect a few requests to make changes so your code is in-line.

If your change is particularly significant, it may be referred to the forum for further community discussion.

A core committer will also "label" your PR using the labels defined in GitHub, these are to correctly classify and help find your work at a later date.

GitHub Labels

The current GitHub labels are grouped into five sections:

  1. Impact - What impact does this bug/issue/fix have, does it break a feature completely, is it just a side effect or is it trivial and not a bit problem (but a bit annoying). Impact is evaluated in the context of the CMS as a whole, rather than against the individual module the issue is raised on.
  2. Complexity - What level of technical proficiency is required to address this issue?
  3. Type - The type of solution required to address this issue
  4. Affects - The release line this issue is relevant to
  5. RFC - The issue is a request-for-comment
impact/criticalWebsite breaking issue with no workarounds. Reserved only for bugs. Bugfix's will target all supported minor release lines.
impact/highAffects a major usage flow. Broken functionality with no obvious workarounds available, or an enhancement that provides a clear benefit to users
impact/mediumWhen affecting a major usage flow, for bugs there is a workaround available and for enhancements there would be a reasonable benefit to users. For a less common usage flow there is broken functionality and for enhancements there is a clear benefit to users.
impact/lowA nuisance but doesn't break any functionality (typos, etc). For enhancements there would only be a limited benefit to users.
complexity/lowSomeone with limited Silverstripe CMS experience could resolve
complexity/mediumSomeone with a good understanding of Silverstripe CMS could resolve
complexity/highOnly an expert with Silverstripe CMS could resolve
type/bugDoes not function as intended, or is inadequate for the purpose it was created for
type/enhancementNew feature or improvement for either users or developers
type/api-breakAn API-breaking change requiring a new major release
type/uxImpact on the CMS user interface
type/docsA docs change
type/userhelpA userhelp documentation change
affects/*Issue has been observed on a specific CMS release line
rfc/draftRFC under discussion
rfc/acceptedRFC where agreement has been reached

Quickfire Do's and Don't's

If you aren't familiar with git and GitHub, try reading the "GitHub bootcamp documentation". We also found the free online git book and the git crash course useful. If you're familiar with it, here's the short version of what you need to know. Once you fork and download the code:

  • Don't develop on the master branch. Always create a development branch specific to "the issue" you're working on (on our GitHub repository's issues). Name it by issue number and description. For example, if you're working on Issue #100, a DataObject::get_one() bugfix, your development branch should be called 100-dataobject-get-one. If you decide to work on another issue mid-stream, create a new branch for that issue--don't work on both in one branch.
  • Do not merge the upstream master with your development branch; rebase your branch on top of the upstream master.
  • A single development branch should represent changes related to a single issue. If you decide to work on another issue, create another branch.
  • Squash your commits, so that each commit addresses a single issue. After you rebase your work on top of the upstream master, you can squash multiple commits into one. Say, for instance, you've got three commits in related to Issue #100. Squash all three into one with the message "Description of the issue here (fixes #100)" We won't accept pull requests for multiple commits related to a single issue; it's up to you to squash and clean your commit tree. (Remember, if you squash commits you've already pushed to GitHub, you won't be able to push that same branch again. Create a new local branch, squash, and push the new squashed branch.)
  • Choose the correct branch: see Picking the right version.

Editing files directly on

If you see a typo or another small fix that needs to be made, and you don't have an installation set up for contributions, you can edit files directly in the web interface. Every file view has an "edit this file" link.

After you have edited the file, GitHub will offer to create a pull request for you. This pull request will be reviewed along with other pull requests.

Check List

  • Adhere to our coding conventions
  • If your patch is extensive, discuss it first on the Silverstripe CMS Forums (ideally before doing any serious coding)
  • When working on existing tickets, provide status updates through ticket comments
  • Check your patches against the "master" branch, as well as the latest release branch
  • Write unit tests
  • Write Behat integration tests for any interface changes
  • Describe specifics on how to test the effects of the patch
  • It's better to submit multiple patches with separate bits of functionality than a big patch containing lots of changes
  • Only submit a pull request for work you expect to be ready to merge. Work in progress is best discussed in an issue, or on your own repository fork.
  • Document your code inline through PHPDoc syntax. See our API documentation for good examples.
  • Check and update documentation on Check for any references to functionality deprecated or extended through your patch. Documentation changes should be included in the patch.
  • When introducing something "noteworthy" (new feature, API change), update the release changelog for the next release this commit will be included in.
  • If you get stuck, please post to the forum
  • When working with the CMS, please read the "CMS Architecture Guide" first
  • Try to respond to feedback in a timely manner. PRs that go more than a month without a response from the author are considered stale, and will be politely chased up. If a response still isn't received, the PR will be closed two weeks after that.

Commit Messages

We try to maintain a consistent record of descriptive commit messages. Most importantly: Keep the first line short, and add more detail below. This ensures commits are easy to browse, and look nice on (more info about proper git commit messages).

Our changelog generation tool relies upon commit prefixes (tags) to categorize the patches accordingly and produce more readable output. Prefixes are usually a single case-insensitive word, at the beginning of the commit message. Although prefixing is optional, noteworthy patches should have them to fall into correct categories.

APIAddition of a new API, or modification/removal/deprecation of an existing API. Includes any change developers should be aware of when upgrading.
FIXBugfix on something developers or users are likely to encounter.
DOCAny documentation changes.
NEWNew feature or major enhancement (both for users and developers)
ENHImprovements of existing functionality (with no API changes), UI/UX enhancements, refactoring and configuration updates.
MNTMaintenance commits that have no impact on users and applications (e.g. CI configs)
DEPDependency version updates (updates for composer.json, package.json etc)
MergePR merges and merge-ups

If you can't find the correct prefix for your commit, it is alright to leave it untagged, then it will fall into "Other" category.

Further guidelines:

  • Each commit should form a logical unit - if you fix two unrelated bugs, commit each one separately
  • If you are fixing a issue from our bugtracker (see Reporting Bugs), please append (fixes #<ticketnumber>)
  • When fixing issues across repos (e.g. a commit to framework fixes an issue raised in the cms bugtracker), use (fixes silverstripe/silverstripe-cms#<issue-number>) (details)
  • If your change is related to another commit, reference it with its abbreviated commit hash.
  • Mention important changed classes and methods in the commit summary.

Example: Bad commit message

finally fixed this dumb rendering bug that Joe talked about ... LOL
also added another form field for password validation

Example: Good commit message

FIX Formatting through prepValueForDB() 

Added prepValueForDB() which is called on DBField->writeToManipulation() 
to ensure formatting of value before insertion to DB on a per-DBField type basis (fixes #1234).
Added documentation for DBField->writeToManipulation() (related to a4bd42fd).