From ActiveRecord to MongoMapper

[Cris Shupp]

I will apologize in advance for what must be a question asked hundreds of times before, and, if so, show a real lack of google skills....

I have an existing Rail 4.0 app that has used JRuby, Oracle and ActiveRecord.  Are there any tutorials out there that cover how to convert existing models into MongoMapper::Document models?

Thanks,

Cris

[Jon Kern]

First time i saw a question like this…

Check out the docs: http://mongomapper.com/documentation/documents/document.html

A mongomapper class is like "butta."

Maybe this is helpful: http://technicaldebt.com/getting-started-with-ruby/mongomapper-ith-rails-quickstart/

You’ll likely need to brush up on the world of NoSQL?

http://docs.mongodb.org/manual/core/data-modeling-introduction/

Some classic SQL joins could be replaced as embedded. But a lot depends on… well, it just depends. Read.

Do a quick dummy project with a model or two that look a lot like your AR models… use the generator, use the scaffold stuff, just to get your feet wet and see how easy it is.

FWIW: Another popular ORM is Mongoid… Might be more tutorials and hand-holding over there.

Write down your experience and your steps, you may be the one who posts the first tutorial on the subject :-)

You may have to do a data migration, and do indexes to match your usages, etc. For the migration, nothing says you can’t have one model class associated to the Oracle & AR method, and the new model associated to the Mongo Database. And invoke the “create” on the mongo class seeding it with inform from your oracle record. Lots of details left out, esp around join tables ;-)

Jon Kern

blog: http://technicaldebt.com

twitter: http://twitter.com/JonKernPA

github: https://github.com/JonKernPA

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[Justin Dossey]

I converted an app from ActiveRecord to MongoMapper a while back.  A straight conversion of a simple dataset is relatively easy, but if you do that, you miss out on a lot of what MongoDB can offer.  It will take practice to gain understanding of data modeling patterns that are a better fit for MongoDB.  

Justin Dossey

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