Please compare their strengths and weaknesses.
A:
I am also curious about what info could come out of attempts at answering this question. Though, I do not like the imperative formulation of the question. It should be a question, not an order.
On the other hand, instead of naming the ORMs at the head of the question, this enumeration should have been done in the body of the question, and it should include more possibilities. That I know, mongomapper, mongoid, activerecord, datamapper, sequel and couchrest are all ruby orms.
Since I have only used ActiveRecord, I cannot answer this question. Though, I have read a little about DataMapper and what I understood is that while ActiveRecord is migration-based and generates the classes according to the database structure, Datamapper does the opposite - that is: it generates the database according to the classes definition.
Additionally, it seems that ActiveRecord and DataMapper are well known orm design patterns: they are well described here: http://msdn.microsoft.com/en-us/magazine/dd569757.aspx#id0400052
Pedro Morte Rolo
2010-05-18 13:12:33
I would say there are lots of questions that begin with the words I used in mine. You may try the search and see them. As for the ORMs, you're right, I would have specified that I was interested only in ones to the relational databases, especially standalone ones, I enlisted.Now, I would mention that ActiveRecord is good at finding objects and in building model associations with ease, meanwhile Sequel is extremely good at filtering datasets due to its chaining capability and its sexy DSL. Datamapper is also chainable, but it seems very "djangoish" and it lacks good documentation.
MG
2010-06-18 13:06:36