This question is still relevant until today. And with rails' features are increasing over the time, I want to add a new answer.
There are so many gems right now, so what you can achieve in Rails, most likely you can achieve it too in Sinatra. If we want to compare between Rails and Sinatra (or any other frameworks), we just need to compare the performance and the ease of use.
One of Rails doctrine is convention over configuration. When you create a project in Rails, automatically you get many gems included in your Gemfile
. Not only gems, when you look at config
directory, you'll see many things included. This doctrine is the reason why the magic can happen in the first place. Once you break the convention, you have to modify -or even create- your configuration.
When we want to have more flexibility but still not reinvent the wheel, we can use framework like Sinatra, where only not so many features is enabled when we first create the project. Even so, I've created mini rails from Sinatra: I just adopting rails' way, with libs/gems that I really need. Because I need to develop my own configuration, the development time was longer than using rails.
If you see this web frameworks benchmark, you'll see that Rails is so slow while other ruby framework, like Sinatra, can be found much higher than Rails.
So, when the best to use Rails?
- You need fast development time. Just follow the convention;
- The future features of your apps are still unknown.
When the best to use Sinatra?
- You don't need fast development time;
- Sinatra can be fast if you only work in mini project;
- You know that you won't add many features in the future.
What do you gain from Rails? Development speed.
What do you gain from Sinatra? Flexibility.