upgrading to Mongoid 3.0

[Andreas Saebjoernsen]

It's less than 12 hours to Mongoid 3.0 is due, but it depends on the
unreleased MongoDB 2.2. Looking at the MongoDB Jira issue tracker
there are about 150 open issues marked for 2.2, it therefore seems
unlikely that it will be released at or close to the Mongoid 3.0
release time. Please let me know if there is a recommended upgrade
procedure to Mongoid 3.0, and if there are any configuration choices
in Mongoid 2.4-stable that reduce the number of breaking changes in
the upgrade.

There are several breaking changes in Mongoid 3.0, so when it's
released I'd producing new applications in this version instead of
2.4-stable. However, our databases are hosted by MongoHQ so this may
not be an option.

Please let me know how you recommend upgrading to Mongoid 3.0, and if
there are some configuration options in 2.4-stable that minimize the
number of breaking changes in the upgrade.

Thank you in advance for you assistance.

Best,
Andy

[Durran Jordan]

I'm going to push that deadline back since I still have some open issues left for 3.0 to flush out first. I've had all our Mongoid apps on master for a while to make sure all the changes there are still good, and just moved them over to the moped-integration branch before I merge that in and want to give them at least a week of hammering on it before shipping.

As for the upgrade, I think it should be fairly simple. I have tried with every backwards incompatible change to have Mongoid raise a specific error when the old syntax is used, and give you instructions on how to change it... An example will be with changes in the index syntax - you'll get an error like this:

-----
     Mongoid::Errors::InvalidIndex:
      
       Problem:
         Invalid index specification on Person: age
       Summary:
         Indexes in Mongoid are defined as a hash of field name and direction/2d pairs,
         with an :options hash for any additional options.
       Resolution:
         Ensure that the index conforms to the correct syntax and has the correct options.
      
        Valid options are:
          background: true|false
          drop_dups: true|false
          name: 'index_name'
          sparse: true|false
          unique: true|false
      
        Valid types are: 1, -1, '2d'
      
        Example:
          class Band
            include Mongoid::Document
            index name: 1, label: -1, options: { sparse: true }
            index location: '2d', options: { background: true }
          end
----

All error messages in Mongoid 3 follow this format. You get a general message indicating the problem, a summary which details why it happened, and a resolution with what you need to do to address it with example code. You can get an idea of how detailed these are now here: https://github.com/mongoid/mongoid/blob/master/lib/config/locales/en.yml

I'm hoping that's all it takes - just do what the exceptions tell you and I expect the upgrade to be quick and easy, as from here on out I am treating exceptions at the framework level as documentation, not just simple errors. There will be a simultaneous release of the new docs, which are much more in depth, and I've been really good on keeping the CHANGELOG up to date with all the changes that you might encounter as well, with code examples there: https://github.com/mongoid/mongoid/blob/master/CHANGELOG.md

None of the backwards incompatible changes will force a data migration or hinder any sort of compatibility with MongoHQ. The MongoHQ team graciously donated several databases with different configs to make sure that Mongoid is completely compatible and we have no hiccups - and I've got automated tests around all configurations, single-server, replica sets, and shards. 1 of our production apps is on Mongoid master pointed at a MongoHQ replica set, the others we have on different rackspace configurations running MRI and JRuby to make sure everything is covered.

Once the moped-integration branch goes into master, I'll post an update here as that's the final stretch. I've been working all this holiday weekend to get this all done, but I don't want to rush it if it's not finished... So I expect at least another week.

2012/4/8 Andreas Saebjoernsen <and...@digitalplaywright.com>

[Andreas Saebjoernsen]

Hi Durran,

Thank you for the quick reply and clarification. I prefer strict
consistency, so I'd like to migrate if the new version persists in a
different way from the old, even if it is not necessary. Doesn't 3.0
for instance improve precision when persisting time?

Best,
Andreas

[Durran Jordan]

3.0 no longer strips any precision off time, but it wont affect anything that was already persisted with the milliseconds stripped previously. But I'll make a note on the website upgrade section on the best way to migrate that if you desire to.

2012/4/10 Andreas Saebjoernsen <and...@digitalplaywright.com>

[Andreas Saebjoernsen]

That sounds great.

Thank you for all your hard work on Mongoid and great support.

Best,
Andreas

[Mauricio Almeida]

Durran,

I'm starting a new project and I would like to use Mongoid 3.0, but I have to stick with the latest stable release here at work. Do you think the new gem and website/documentation will be released until next week or should I stick with 2.4.8?

Thanks in advance!

Mauricio Almeida

@brandnewcode

[Durran Jordan]

I'm currently shooting for Monday the 23rd, most notably because I have the 23rd - 31st off for vacation and can be available full-time for support that week. And gives me 11 more days to get the documentation and remaining issues finished.

2012/4/12 Mauricio Almeida <mauric...@gmail.com>

[Mauricio Almeida]

That will be great! Thank you very much for your effort!

[khelll]

Durran, when are you planning to release V 3.0? I'm planning a new release of my project and want to try the new version.

Thanks

[Durran Jordan]

Any day now... I was trying for last week, but then went out of town on the weekend. Going to shoot for this week now.

2012/4/29 khelll <khe...@gmail.com>