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83 lines
2.8 KiB
83 lines
2.8 KiB
11 years ago
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Basic concepts of Yii
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=====================
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Component and Object
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--------------------
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Yii 2.0 breaks the `CComponent` class in 1.1 into two classes: `Object` and `Component`.
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The `Object` class is a lightweight base class that allows defining class properties
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via getters and setters. The `Component` class extends from `Object` and supports
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the event feature and the behavior feature.
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If your class does not need the event or behavior feature, you should consider using
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`Object` as the base class. This is usually the case for classes that represent basic
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data structures.
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Object Configuration
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--------------------
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The `Object` class introduces a uniform way of configuring objects. Any descendant class
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of `Object` should declare its constructor (if needed) in the following way so that
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it can be properly configured:
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```php
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class MyClass extends \yii\base\Object
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{
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public function __construct($param1, $param2, $config = [])
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{
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// ... initialization before configuration is applied
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parent::__construct($config);
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}
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public function init()
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{
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parent::init();
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// ... initialization after configuration is applied
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}
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}
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```
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In the above, the last parameter of the constructor must take a configuration array
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which contains name-value pairs for initializing the properties at the end of the constructor.
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You can override the `init()` method to do initialization work that should be done after
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the configuration is applied.
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By following this convention, you will be able to create and configure a new object
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using a configuration array like the following:
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```php
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$object = Yii::createObject([
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'class' => 'MyClass',
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'property1' => 'abc',
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'property2' => 'cde',
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], $param1, $param2);
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```
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More on configuration in [configuration](configuration.md)
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Path Alias
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----------
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Yii 2.0 expands the usage of path aliases to both file/directory paths and URLs. An alias
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must start with a `@` character so that it can be differentiated from file/directory paths and URLs.
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For example, the alias `@yii` refers to the Yii installation directory. Path aliases are
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supported in most places in the Yii core code. For example, `FileCache::cachePath` can take
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both a path alias and a normal directory path.
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Path alias is also closely related with class namespaces. It is recommended that a path
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alias be defined for each root namespace so that you can use Yii the class autoloader without
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any further configuration. For example, because `@yii` refers to the Yii installation directory,
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a class like `yii\web\Request` can be autoloaded by Yii. If you use a third party library
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such as Zend Framework, you may define a path alias `@Zend` which refers to its installation
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directory and Yii will be able to autoload any class in this library.
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Autoloading
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-----------
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TBD
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