When comparing Ruby on Rails vs Flask, the Slant community recommends Flask for most people. In the question“What are the best backend web frameworks?” Flask is ranked 2nd while Ruby on Rails is ranked 5th. The most important reason people chose Flask is:
Even though it's pretty minimalistic out of the box, Flask still provides the necessary tools to build a quick prototype for a web app right after a fresh install. With all the main components pretty much packed in the `flask` package, building a simple web app in a single Python file is as easy as it gets.
Ranked in these QuestionsQuestion Ranking
Pro Small projects are very easy and it's possible to finish one in very little time
The large number of documentation, tutorials, videos and guides which help new developers who are just starting with Rails make it seem very easy to create a small and simple application by relying on code generation and components that come out of the box with Rails.
Pro Many plugins (gems) available
There are many third-party plugins (Ruby gems) available for Rails development. The larger ones and those that have a lot of downloads and users are very well documented and easy to use.
Pro Massive community with lots of tutorials and guides
The sheer scale and massive number of developers using Rails has produced a large number of guides, tutorials, plugins, documentation, videos and anything that can help new and old Rails developers.
Pro Ruby is a nice readable language
Ruby has a very clean syntax that makes code easier to both read and write than more traditional Object Oriented languages, such as Java. For beginning programmers, this means the focus is on the meaning of the program, where it should be, rather than trying to figure out the meaning of obscure characters.
presidents = ["Ford", "Carter", "Reagan", "Bush1", "Clinton", "Bush2"] for ss in 0...presidents.length print ss, ": ", presidents[presidents.length - ss - 1], "\n"; end
Pro Good conventions
MVC is a great starting point, and perfect for APIs. You'll rarely if ever have to wonder "where should I put this code?"
Pro Supported on every major cloud or VPS hosting service
Rails is supported on every major Cloud hosting service nowadays. There are also countless tutorials that help developers deploy their Rails apps if there are any problems on the way.
Pro Cool language
Pro Meta-programming capabilities
Pro Extremely easy to build a quick prototype
Even though it's pretty minimalistic out of the box, Flask still provides the necessary tools to build a quick prototype for a web app right after a fresh install. With all the main components pretty much packed in the
flask package, building a simple web app in a single Python file is as easy as it gets.
Pro Lots of resources available online
Flask is one of the most popular Python web frameworks, if not the most popular one. As such, there's plenty of guides, tutorials, and libraries available for it. A large number of important Python libraries, such as SQLAlchemy have libraries for Flask, which add valuable bindings to make the development process and the integration between these libraries and Flask as easy as possible.
Pro Minimalist without losing power
Flask is very easy to get up and going, with vanilla HTML or with bootstrap pieces. It doesn't take much lines of Python to load Flask to get headers working, etc, and since it's all modular you don't have to have something you don't want in your application.
Pro Very flexible
Flask gives developers a lot of flexibility in how they develop their web applications.
For example, the choice of not having an ORM, but instead choosing one suited to the task, or another area where Flask gives a lot of options to developers is the templating. They can use Jinja2, Flask's default templating language or choose from a number of different templating languages they desire.
Pro Great documentation
The official documentation is very thorough and complete. Everything is explained in-depth and followed by extremely well-explained tutorials that tackle real-world problems.
Con Too much magic
So much behavior is implemented with dynamic behind-the-scenes changes to existing classes that obscure bugs are way too common. Conflicting interactions between multiple plugins that both try to change the same objects are a particularly pernicious example.
Con Learning curve seems low at first, but starts becoming steeper
Rails' simplicity is deceptive. It's learning curve is really low at first, and the huge number of tutorials and guides out there for starting with Rails make it even easier. But it starts getting harder and harder as apps become more complicated. If good code conventions and OO design are not followed, then the codebase will be all over the place and it becomes impossible to maintain it.
Con Not a very popular language outside of web development
Con Too much convention
Con Bad performance
Among the slowest frameworks. If you want to scale, you will have to migrate to another land.
Con Not async-friendly
Flask is explicitly not designed to handle async programming.
Con Threadlocals and globals used everywhere
The default way of creating applications in flask makes it hard to use reusable and clean code.
Con Setting up a large project requires some previous knowledge of the framework
Setting up a large project with Flask is not that easy considering how there's no "official" way of doing it. Blueprints are a useful tool in this regard but require some additional reading and are a bit tricky to get right for a beginner.
The lack of some defaults can also be problematic. Having to choose between different libraries for a certain task is never easy, especially if you have never worked with Flask before.