What is an ORM?

What is an ORM?
Orm was a worm, featured in the popular British CITV show, Orm and Cheep..... But we're not talking the puppet variety here, instead we're concentrating on the computer science version of ORM. It stands for Object-relational mapping, and is sometimes also abbreviated as O/RM or O/R mapping.

ORM is a programming technique for converting data between incompatible type systems in object-oriented programming languages, such as Ruby. This creates, in effect, a "virtual object database" that can be used from within the programming language.

In short, it's like a translator.

In our Makers Academy Ronin course we are coding with Ruby, and this week we want to be able to use a Postgres database. The problem is Ruby doesn't want to communicate directly with the database, and I still don't have a magical code wand that will fix all issues! So we use an ORM. Depending on your coding platform there are a variety of different types of ORM available (I'd actually had some experience of CakePHP when using a MySQL database before, although I hadn't really thought of it how it functioned until now). For Ruby there is ActiveRecord (which is part of the Rails environment), iBATIS, and our ORM of choice for this weerk, DataMapper.

DataMapper, like any ORM, can be a bit tricky to set up initially (although I suppose like everything the more you do it the easier it will become), especially if you're using a Linux system (but we won't go there today!). But once done it allows us to write code in a Ruby-ish style that will be fed through the ORM to the database. Bish-bosh, minimal coding headaches.

Another big plus for using an ORM is that it keeps your databases separate from your actual code, which means multiple users can connect to multiple databases.

We like a good ORM!

Now if only Cheep could fly....