The document discusses 10 common gotchas or mistakes when using the Mongoid ORM for MongoDB in production applications. It begins with introductions and then lists the 10 gotchas as follows: MongoDB is not relational, MongoDB only uses one index per query, nil does not unset a field, nil is not the opposite of exist, BigDecimal type sorts alphabetically, embedded objects must have an embedded_in declared, indexes don’t get created on embedded objects, scopes should go on the parent object, callbacks on embedded objects are not run by default, and don’t try to perform two atomic operations on the same field in the same call. It concludes by thanking the audience and providing links to additional resources.

1. Mongoid Ate My
Homework
10 quick gotchas from using mongoid in production.
- Jude

2. I’m @slowjud on everything
(twitter/github)
I work at SplitIt.
We run www.betterbills.com
We run www.betterbills.com
We run www.betterbills.com
We run www.betterbills.com

3. Gratuitous bike porn

4. Now for my talk

6. MongoDB is not
relational

7. MongoDB only uses
one index per query

9. Nil does not unset a
field

11. Nil is not the opposite
of exist

13. BigDecimal type sorts
alphabetically

15. Embedded objects must
have an embedded_in
declared

17. Indexes don’t get created
on embedded objects

19. Scopes should go on
the parent object

20. Callbacks on embedded
objects are not run by
default

22. Don’t try and perform two
atomic operations on the
same field in the same call

24. Questions?

25. Gists
Slides: http://www.slideshare.net/slowjud/mongoid-ate-my-homework
The good models: https://gist.github.com/slowjud/9476959
The bad models: https://gist.github.com/slowjud/9476981
All of the queries: https://gist.github.com/slowjud/9477341

26. Thank You