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40 lines
1.7 KiB
Markdown
40 lines
1.7 KiB
Markdown
Helper Classes
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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 forth. 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:
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```
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use yii\helpers\ArrayHelper;
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$c = ArrayHelper::merge($a, $b);
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```
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Extending Helper Classes
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------------------------
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To make helper classes easier to extend, Yii breaks each helper class into two classes: a base class (e.g. `BaseArrayHelper`)
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and a concrete class (e.g. `ArrayHelper`). When you use a helper, you should only use the concrete version, never use the base class.
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If you want to customize a helper, perform the following steps (using `ArrayHelper` as an example):
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1. Name your class the same as the concrete class provided by Yii, including the namespace: `yii\helpers\ArrayHelper`
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2. Extend your class from the base class: `class ArrayHelper extends \yii\helpers\BaseArrayHelper`.
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3. In your class, override any method or property as needed, or add new methods or properties.
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4. Tell your application to use your version of the helper class by including the following line of code in the bootstrap script:
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```php
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Yii::$classMap['yii\helpers\ArrayHelper'] = 'path/to/ArrayHelper.php';
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```
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Step 4 above will instruct the Yii class autoloader to load your version of the helper class instead of the one included in the Yii distribution.
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> Tip: You can use `Yii::$classMap` to replace ANY core Yii class with your own customized version, not just helper classes.
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