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81 lines
2.7 KiB
Markdown
81 lines
2.7 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 [customizing helper classes](#customizing-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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-------------------
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The following core helper classes are provided in the Yii releases:
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- [ArrayHelper](helper-array.md)
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- Console
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- FileHelper
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- FormatConverter
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- [Html](helper-html.md)
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- HtmlPurifier
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- Imagine (provided by yii2-imagine extension)
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- Inflector
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- Json
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- Markdown
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- StringHelper
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- [Url](helper-url.md)
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- VarDumper
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Customizing Helper Classes <span id="customizing-helper-classes"></span>
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--------------------------
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To customize a core helper class (e.g. [[yii\helpers\ArrayHelper]]), you should create a new class extending
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from the helpers corresponding base class (e.g. [[yii\helpers\BaseArrayHelper]]) and name your class the same
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as the corresponding concrete class (e.g. [[yii\helpers\ArrayHelper]]), including its namespace. This class
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will then be set up to replace the original implementation of the framework.
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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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<?php
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namespace yii\helpers;
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class ArrayHelper extends BaseArrayHelper
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{
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public static function merge($a, $b)
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{
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// your custom implementation
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}
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}
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```
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Save your class in a file named `ArrayHelper.php`. The file can be in any directory, for example `@app/components`.
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Next, in your application's [entry script](structure-entry-scripts.md), add the following line of code
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after including the `yii.php` file to tell the [Yii class autoloader](concept-autoloading.md) to load your custom
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class instead of the original helper class from the framework:
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```php
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Yii::$classMap['yii\helpers\ArrayHelper'] = '@app/components/ArrayHelper.php';
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```
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Note that customizing of helper classes is only useful if you want to change the behavior of an existing function
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of the helpers. If you want to add additional functions to use in your application, you may be better off creating a separate
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helper for that.
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