在 Yii 中，小部件（Widget）是用于封裝常見(jiàn) UI 元素或邏輯的可重用組件。其核心作用是提高開(kāi)發(fā)效率并保持界面一致性。使用 Yii 小部件可以避免重復(fù)編寫代碼，實(shí)現(xiàn)代碼復(fù)用、保持界面統(tǒng)一、分離關(guān)注點(diǎn)、便于擴(kuò)展。Yii 提供了多種內(nèi)置小部件，如 ActiveForm 用于模型表單、ListView/GridView 顯示列表和表格數(shù)據(jù)、Pagination 實(shí)現(xiàn)分頁(yè)控制、Menu 動(dòng)態(tài)生成導(dǎo)航菜單。當(dāng)發(fā)現(xiàn)視圖代碼重復(fù)、需要組合邏輯與展示、或抽象動(dòng)態(tài)行為時(shí)，應(yīng)創(chuàng)建自定義小部件。創(chuàng)建方法為繼承 yii\base.Widget 并實(shí)現(xiàn) run() 方法，然后通過(guò) widget() 方法調(diào)用并傳入配置選項(xiàng)即可。

Yii widgets are reusable components that help you build user interfaces more efficiently in Yii applications. Their main purpose is to encapsulate commonly used UI elements or logic, so you don’t have to write the same code over and over.

What Exactly Are Widgets in Yii?

Widgets in Yii are PHP classes that generate HTML or JavaScript-based interface elements. Think of them as building blocks for your front-end — things like form inputs, navigation menus, date pickers, or even something like a comment section. Each widget is self-contained, meaning it handles its own rendering and behavior.

For example, instead of manually writing out a dropdown menu with PHP loops and conditions every time, you can use Dropdown widget provided by Yii or create your own custom version.

Why Use Widgets?

Using widgets has several practical benefits:

• Code Reuse: Once you create a widget, you can use it across multiple pages or projects.
• Consistency: Ensures uniform look and behavior across your app.
• Separation of Concerns: Keeps your views cleaner by moving complex logic into widget classes.
• Extensibility: You can extend existing widgets to customize their behavior without rewriting everything.

If you're working on a large project with repetitive UI patterns, widgets become especially useful.

How Do You Use Built-in Widgets?

Yii comes with a set of built-in widgets that cover common use cases. Here's how you typically use them:

<?= \yii\widgets\Menu::widget([
    'items' => [
        ['label' => 'Home', 'url' => ['/site/index']],
        ['label' => 'About', 'url' => ['/site/about']],
    ],
]) ?>

Some commonly used ones include:

• ActiveForm: For creating model-based forms.
• ListView / GridView: For displaying lists or tabular data.
• Pagination: Handles pagination controls.
• Menu: Builds navigation menus dynamically.

You usually pass an array of configuration options to define how the widget should behave or render.

When Should You Create Custom Widgets?

You might want to build a custom widget if:

• You find yourself repeating the same block of view code.
• You need a component that combines both logic and presentation.
• You want to abstract some dynamic behavior (like AJAX loading) into a reusable part.

Creating a custom widget involves defining a class that extends yii\base\Widget, and implementing the run() method. Then you call it like any other widget:

<?= MyCustomWidget::widget(['option1' => $value]) ?>

It’s not hard, but it does require organizing your code properly and sometimes thinking ahead about flexibility and configuration.

基本上就這些。

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