Yii2 での DropDownList の簡単な使用例

<?php
use common\models\Category;
use yii\helpers\ArrayHelper;
use yii\helpers\Html;
use yii\widgets\ActiveForm;
/* @var $this yii\web\View */
/* @var $model common\models\Category */
/* @var $form yii\widgets\ActiveForm */
?>
<div class="category-form">
  <div class="row">
    <?php
    if (!$model->isNewRecord) {//如果是编辑分类
      $cate = ArrayHelper::map(Category::find()->andWhere(&#39;id != :id&#39;, [&#39;:id&#39; => $model->id])->all(), &#39;id&#39;, &#39;title&#39;);
    } else {//如果是新建分类
      $cate = ArrayHelper::map(Category::find()->all(), &#39;id&#39;, &#39;title&#39;);
    }
    ?>
    <div class="col-md-6 col-md-offset-3">
      <?php $form = ActiveForm::begin(); ?>
      <?= $form->field($model, &#39;title&#39;)->textInput([&#39;maxlength&#39; => 100])->label("分类标题") ?>
      <?= $form->field($model, &#39;name&#39;)->textInput([&#39;maxlength&#39; => 100])->label("分类别名") ?>
      <?= $form->field($model, &#39;pid&#39;)->dropDownList($cate, [&#39;prompt&#39; => &#39;请选择父分类&#39;])->label("父分类") ?>
      <?= $form->field($model, &#39;keywords&#39;)->textarea([&#39;maxlength&#39; => 255])->label("分类关键词") ?>
      <?= $form->field($model, &#39;description&#39;)->textarea([&#39;maxlength&#39; => 255])->label("分类描述") ?>
      <div class="form-group">
        <div class="row">
          <div class="col-md-6 col-md-offset-3">
            <?= Html::submitButton($model->isNewRecord ? &#39;创建&#39; : &#39;更新&#39;, [&#39;class&#39; => $model->isNewRecord ? &#39;btn btn-block btn-success&#39; : &#39;btn btn-block btn-primary&#39;]) ?>
          </div>
        </div>
      </div>
      <?php ActiveForm::end(); ?>
    </div>
  </div>
</div>