The differences between .build, .create, and .create! and when should they be used?

Question

So I\'ve been seeing people using .build, .create, and .create! within their controllers more and more lately. What\'s the difference

Answer 1

There are a couple differences, but they're not big:

1. .create is equivalent to .new followed by .save. It's just more succinct.
2. .create! is equivalent to .new followed by .save! (throws an error if saving fails). It's also just a wee bit shorter
3. I think .build is mostly an alias for .new. It works one way in Rails 3 and another way in Rails < 3.x

The most important part, however, is that these methods can be called through an association (has_many, etc.) to automatically link the two models.