When comparing Yii vs Flask, the Slant community recommends Flask for most people. In the question“What are the best backend web frameworks?” Flask is ranked 7th while Yii is ranked 21st. The most important reason people chose Flask is:
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.
Specs
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Pros
Pro Rapid development through code scaffolding
Yii takes care of repetitive tasks through Gii, a web-based scaffolding tool. Gii takes care of code generation and creating code templates for:
- Models
- Controllers
- Forms
- Modules
- Extensions
- CRUD controller actions and views
- There are a lot of scaffolding templates made by community for Gii, that improve generated code functionality by a lot.
- Gii is very easy to extend yourself.
Pro Comes with important security standarts
Since security is a crucial part of any application, Yii comes with great security features out of the box to help developers create a secure and reliable application. These security features contain but are not restricted to:
- Input validation
- Output filtering
- Features against SQL injection
- Cross-site scripting prevention
Pro Highly extensible
Yii is built to be extremely extensible. Virtually every component of the framework can be extended programmatically. For example, if you want to add a unique id to your views, it's very easy to do:
namespace app\components;
class View extends yii\web\View {
public $bodyId;
/* Yii allows you to add magic getter methods by prefacing method names with "get" */
public function getBodyIdAttribute() {
return ($this->bodyId != '') ? 'id="' . $this->bodyId . '"' : '';
}
}
Pro Integrated with a testing framework
Yii makes use of Codeception, a great PHP testing framework that helps developers run their tests. They can be unit, functional or acceptance tests since Codeception supports them all.
Pro Lots of plugins available
Yii has about 2000 addons hosted on Yii's official website. These addons significantly decrease development time and increase the developer's efficiency.
Pro License
Yii is free and open source and is distributed under the BSD License.
Pro Strong community support
Yii has a strong and rather large community behind it. This is proven by the great number of blog posts, tutorials, guides and reviews on the Yii framework as well as the great number of extensions developed for it.
Pro Easy to install
Yii uses Composer to handle it's dependency installation. This is rather easy and not very time consuming, although it should be noted that Composer is very resource-intensive considering what it's job is. But that is not really Yii's fault.
Pro Best framework for CRUD operation
Yii Framework Provides most of features require for crud functionalities like GridView, Listview and DetailView (with jquery search and validation functions) by generating using GII.
Pro Highly extensible without effort
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 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 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 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.
Pro Able to use ORM or "true SQL"
Cons
Con Can be hard for beginners
Since Yii requires developers to write code following certain rules, or in other words, it requires developers to follow the "Yii way of doing things" it can be hard for beginners to warm up to it and start using it right away.
Con Not very good at many to many relations
(but there is a good plugin, namely CAdvancedArBehavior extension to do this)
Con Not async-friendly
Flask is explicitly not designed to handle async programming.
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.
Con Threadlocals and globals used everywhere
The default way of creating applications in flask makes it hard to use reusable and clean code.
Con HTML-oriented, not API-oriented
Not necessarily designed for making APIs, though that is possible