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76 lines
2.2 KiB
Markdown
76 lines
2.2 KiB
Markdown
Helpers
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=======
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> Note: This section is under development.
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Yii provides many classes that help simplify common coding tasks, such as string or array manipulations,
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HTML code generation, and so on. These helper classes are organized under the `yii\helpers` namespace and
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are all static classes (meaning they contain only static properties and methods and should not be instantiated).
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You use a helper class by directly calling one of its static methods, like the following:
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```php
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use yii\helpers\Html;
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echo Html::encode('Test > test');
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```
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> Note: To support [extending helper classes](#extending-helper-classes), Yii breaks each core helper class
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into two classes: a base class (e.g. `BaseArrayHelper`) and a concrete class (e.g. `ArrayHelper`).
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When you use a helper, you should only use the concrete version and never use the base class.
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## Core Helper Classes
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The following core helper classes are provided in the Yii releases:
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- ArrayHelper
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- Console
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- FileHelper
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- Html
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- HtmlPurifier
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- Image
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- Inflector
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- Json
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- Markdown
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- Security
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- StringHelper
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- Url
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- VarDumper
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## Extending Helper Classes
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To custom a core helper class (e.g. `yii\helpers\ArrayHelper`), you should extend from its corresponding base class
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(e.g. `yii\helpers\BaseArrayHelper`) and name your class the same as the corresponding concrete class
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(e.g. `yii\helpers\ArrayHelper`), including its namespace.
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The following example shows how to customize the [[yii\helpers\ArrayHelper::merge()|merge()]] method of the
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[[yii\helpers\ArrayHelper]] class:
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```php
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namespace yii\helpers;
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use yii\helpers\BaseArrayHelper;
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class ArrayHelper extends BaseArrayHelper
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{
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public static function merge($a, $b)
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{
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// your custom implementation
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}
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}
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```
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Save your class in a file named `ArrayHelper.php`. The file can be in any directory, such as `@app/components`.
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Next, in your application's [entry script](structure-entry-scripts.md), add the following line of code
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after including the `yii.php` file:
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```php
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Yii::$classMap['yii\helpers\ArrayHelper'] = 'path/to/ArrayHelper.php';
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```
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The above line instructs the [Yii class autoloader](concept-autoloading.md) to load your version of the helper
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class, instead of the one included in the Yii releases.
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