The Doctrine team is proud to announce that MongoDB ODM 1.3.0 and 2.0.0-RC2 have
been released. These releases are the culmination of a long effort to migrate
the ODM away from the legacy
mongo extension to the new MongoDB driver
mongodb extension and PHP library). This results in a number of BC breaks for
users, but will enable us to add many new features in future releases, among
them support for multi-document transactions.
MongoDB ODM 1.3.0 is a compatibility release targeted for users of the legacy extension that want to migrate to MongoDB ODM 2.0. It helps identify BC breaks by throwing deprecation notices and offering a forward compatibility layer where possible. To efficiently find usages of deprecated code, you can use the PHPUnit bridge developed by Symfony (symfony/phpunit-bridge) which logs all deprecation notices encountered during a run of PHPUnit. You can read more about this component in the Symfony documentation.
MongoDB ODM 2.0.0RC-2 is the recommended package to use for those starting new projects with MongoDB ODM. It ensures that you use the modern API for ODM without having to worry about deprecations. While this is still a release candidate, it is planned to make this version the next stable MongoDB ODM release.
What’s new in MongoDB ODM 2.0?
Most importantly, this version no longer uses the legacy
mongo extension. That
extension is no longer maintained and does not support server versions beyond
MongoDB 3.0. The new MongoDB driver ensures that MongoDB ODM can leverage
features and improvements contained in newer MongoDB versions, such as support
for multi-document transactions, retryable reads, retryable writes, change
streams, and much more.
Changing the driver also means significant changes to some APIs. Most importantly, the GridFS API has been rewritten from scratch to conform with MongoDB’s GridFS spec for drivers. If you’ve used GridFS before, this will be a big change for you, but the new API is much simpler and cleaner to use. Check out the GridFS documentation to find out how to use the new API. Unfortunately, we cannot provide a forward compatibility layer for this, as re-implementing this API atop the legacy driver is not feasible.
Lazy reference support has been changed completely and no longer uses proxy
objects from the deprecated doctrine/common library. Instead, it builds on
ocramius/proxy-manager, which gives us access to more advanced features like
partial proxy loading, which we will start leveraging in future releases.
In 2.0 we dropped support for the YAML mapping of documents. This step was necessary to both reduce the complexity of the code base and lower the burden of maintaining multiple mapping drivers. If you are currently using YAML mappings, we provide a console command to migrate YAML mappings to the XML format. We are currently working on an alternative that allows for a more flexible mapping configuration system, but this is not ready yet and will only be provided in a future 2.x release.
Migrating to MongoDB ODM 2.0
If you are using MongoDB ODM 1.x, the upgrade consists of multiple steps. First, ensure that you are fulfilling the necessary requisites for MongoDB ODM 2.0:
- PHP version 7.2 or newer
- ext-mongodb 1.5.0 or newer
- mongodb/mongodb library 1.4.0 or newer
- MongoDB 3.0 or newer
If you are already running PHP 7, you will most likely already be running ext-mongodb as the legacy extension is not available for PHP 7. If you are still running PHP 5.x, it is recommended that you migrate to PHP 7 before attempting to use a newer ODM version. You can do so by following the instructions on running ODM 1.x on PHP 7.
Once you fulfill all dependencies, the first step is updating to the latest 1.3 release of MongoDB ODM. If you are using Symfony, you also need to upgrade the ODM bundle to its latest 3.6 version. Once this is done, you can start fixing any deprecation notices that you find. This should be a familiar process for any existing Symfony users. We tried to provide compatibility layers where possible; unfortunately, we could not do so in all cases.
The next step is upgrading to ODM 2.0 directly. For many users, this step shouldn’t be a problem thanks to the compatibility layer in 1.x. There may be some necessary changes depending on the features you use (e.g. GridFS).
What’s next for MongoDB ODM
During the past few years, we focussed our limited development time almost exclusively on the driver migration, which came at the expense of supporting new features in MongoDB. We plan to add support for many of those features in future releases. You can get an overview of what’s planned by checking the roadmap. If you are looking for a specific feature, please let us know in the issue tracker.
While not exhaustive or guaranteed, these are some of the features we plan to implement in future releases:
- Support for multi-document transactions (on-demand and implicit while flushing the Document Manager)
- Support for new aggregation pipeline stages and operators
- Support for the $expr query operator
- Support for aggregation pipelines in update operations
- Support for reading documents from views instead of collections
- Atomic updates for collections using new array update operators
With these releases, we’re also introducing our new support timeline. Along with the two releases announced above, we are also releasing the end-of-life release for MongoDB ODM 1.2. We will not support MongoDB ODM 1.2 any more and encourage users to upgrade to 1.3. Since 1.3 has no additional requirements over 1.2, upgrading should be possible for all users of ODM 1.2.
MongoDB ODM 1.3 will be supported for at least 6 months after the first stable release of ODM 2.0. We will communicate this date when releasing ODM 2.0. After those 6 months, we will either drop support for ODM 1.3 or extend it for another 3 months, depending on the adoption rate of ODM 2.0. We are aware that the number and kind of BC breaks for 2.0 pose a significant challenge for many users, which is why we don’t want to force people to rush into this update.
During the support phase for MongoDB ODM 1.3, we will also continue to provide bug fixes to the MongoDB Abstraction Layer that is used by MongoDB ODM 1.x. This project will reach end-of-life at the same time as MongoDB ODM 1.3, and will no longer be supported beyond that. We encourage users that depend on this library to switch to using the MongoDB PHP Library, which is part of the official MongoDB driver for PHP.
Contributing to MongoDB ODM
We are currently looking for contributors. This doesn’t necessarily mean implementing new features or merging pull requests. Reporting or triaging issues, requesting features, and reporting bugs are all extremely important and helps us deliver better software!
The documentation can be found on the website: https://www.doctrine-project.org/projects/doctrine-mongodb-odm/en/latest/index.html. To get support, contact us via the #mongodb-odm channel within the Doctrine Slack. If you believe you have found a bug, please file a bug report on GitHub.