The application principal is a service locator, which deploys a set of application components that provide various functions to handle requests. For example, the urlManager component is responsible for processing web page requests and routing them to the corresponding controller, the db component provides database-related services, and so on.
In the same application, each application component has a unique ID to distinguish other application components. You can access application components through the following expressions . (Recommended learning: yii tutorial)
\Yii::$app->componentID
For example, you can use \Yii::$app->db to obtain the DB connection registered to the application, use \Yii:: $app->cache to get the primary cache registered to the application.
The first time you use the above expression, an application component instance will be created. Subsequent visits will return this instance, and there is no need to create it again.
Application components can be any objects and can be configured in the application main configuration yii\base\Application::$components attribute. For example:
[
'components' => [
// 使用類名注冊 "cache" 組件
'cache' => 'yii\caching\ApcCache',
// 使用配置數(shù)組注冊 "db" 組件
'db' => [
'class' => 'yii\db\Connection',
'dsn' => 'mysql:host=localhost;dbname=demo',
'username' => 'root',
'password' => '',
],
// 使用函數(shù)注冊"search" 組件
'search' => function () {
return new app\components\SolrService;
},
],
]Information: Please be careful to register too many application components. Application components are like global variables. Using too many may make testing and maintenance more difficult. Generally, local components can be created when needed.
Boot Startup Component
As mentioned above, an application component will only be instantiated when it is accessed for the first time. If there is no access during the processing of the request, it will not be instantiated. Sometimes you want to instantiate a component during every request processing even if it is never accessed. You can add the component ID to the bootstrap attribute of the application body.
You can also use closures to boot custom components. There is no need to directly return an instantiated component. The closure is also called after the application body yii\base\Application is instantiated.
For example, the following application body configuration ensures that the log component is always loaded.
[
'bootstrap' => [
'log',
function($app){
return new ComponentX();
},
function($app){
// 可以寫自定義的代碼
return;
}
],
'components' => [
'log' => [
// "log" 組件的配置
],
],
]Core application components
Yii defines a set of core components with fixed IDs and default configurations. For example, the request component is used to collect user requests and parse routes; db represents A database connection that can perform database operations. Through these components, the Yii application body can handle user requests.
The following is a list of predefined core application components, which can be configured and customized like ordinary application components. When you configure a core component and do not specify its class name, the class specified by Yii by default will be used.
The above is the detailed content of What does yii application component mean?. For more information, please follow other related articles on the PHP Chinese website!
Hot AI Tools
Undress AI Tool
Undress images for free
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Clothoff.io
AI clothes remover
Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!
Hot Article
Hot Tools
Notepad++7.3.1
Easy-to-use and free code editor
SublimeText3 Chinese version
Chinese version, very easy to use
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
SublimeText3 Mac version
God-level code editing software (SublimeText3)
Hot Topics
Yii2 vs Phalcon: Which framework is better for developing graphics rendering applications?
Jun 19, 2023 am 08:09 AM
In the current information age, big data, artificial intelligence, cloud computing and other technologies have become the focus of major enterprises. Among these technologies, graphics card rendering technology, as a high-performance graphics processing technology, has received more and more attention. Graphics card rendering technology is widely used in game development, film and television special effects, engineering modeling and other fields. For developers, choosing a framework that suits their projects is a very important decision. Among current languages, PHP is a very dynamic language. Some excellent PHP frameworks such as Yii2, Ph
Data query in Yii framework: access data efficiently
Jun 21, 2023 am 11:22 AM
The Yii framework is an open source PHP Web application framework that provides numerous tools and components to simplify the process of Web application development, of which data query is one of the important components. In the Yii framework, we can use SQL-like syntax to access the database to query and manipulate data efficiently. The query builder of the Yii framework mainly includes the following types: ActiveRecord query, QueryBuilder query, command query and original SQL query
Symfony vs Yii2: Which framework is better for developing large-scale web applications?
Jun 19, 2023 am 10:57 AM
As the demand for web applications continues to grow, developers have more and more choices in choosing development frameworks. Symfony and Yii2 are two popular PHP frameworks. They both have powerful functions and performance, but when faced with the need to develop large-scale web applications, which framework is more suitable? Next we will conduct a comparative analysis of Symphony and Yii2 to help you make a better choice. Basic Overview Symphony is an open source web application framework written in PHP and is built on
How to use Yii3 framework in php?
May 31, 2023 pm 10:42 PM
As the Internet continues to develop, the demand for web application development is also getting higher and higher. For developers, developing applications requires a stable, efficient, and powerful framework, which can improve development efficiency. Yii is a leading high-performance PHP framework that provides rich features and good performance. Yii3 is the next generation version of the Yii framework, which further optimizes performance and code quality based on Yii2. In this article, we will introduce how to use Yii3 framework to develop PHP applications.
How to use PHP framework Yii to develop a highly available cloud backup system
Jun 27, 2023 am 09:04 AM
With the continuous development of cloud computing technology, data backup has become something that every enterprise must do. In this context, it is particularly important to develop a highly available cloud backup system. The PHP framework Yii is a powerful framework that can help developers quickly build high-performance web applications. The following will introduce how to use the Yii framework to develop a highly available cloud backup system. Designing the database model In the Yii framework, the database model is a very important part. Because the data backup system requires a lot of tables and relationships
What is the difference between php framework laravel and yii
Apr 30, 2025 pm 02:24 PM
The main differences between Laravel and Yii are design concepts, functional characteristics and usage scenarios. 1.Laravel focuses on the simplicity and pleasure of development, and provides rich functions such as EloquentORM and Artisan tools, suitable for rapid development and beginners. 2.Yii emphasizes performance and efficiency, is suitable for high-load applications, and provides efficient ActiveRecord and cache systems, but has a steep learning curve.
Yii with Docker: Containerizing and Deploying Your Applications
Apr 02, 2025 pm 02:13 PM
The steps to containerize and deploy Yii applications using Docker include: 1. Create a Dockerfile and define the image building process; 2. Use DockerCompose to launch Yii applications and MySQL database; 3. Optimize image size and performance. This involves not only specific technical operations, but also understanding the working principles and best practices of Dockerfile to ensure efficient and reliable deployment.
Yii2 vs Symfony: Which framework is better for API development?
Jun 18, 2023 pm 11:00 PM
With the rapid development of the Internet, APIs have become an important way to exchange data between various applications. Therefore, it has become increasingly important to develop an API framework that is easy to maintain, efficient, and stable. When choosing an API framework, Yii2 and Symfony are two popular choices among developers. So, which one is more suitable for API development? This article will compare these two frameworks and give some conclusions. 1. Basic introduction Yii2 and Symfony are mature PHP frameworks with corresponding extensions that can be used to develop
