Simple usage example of DropDownList in Yii2_php example

The example in this article describes the simple usage of DropDownList in Yii2. Share it with everyone for your reference, the details are as follows:

Here we use practical application as an example to explain the usage of Yii2 DropDownList.

There is a classification table, like Infinitus Classification. The table structure is as follows, pid is the parent classification ID
Here we want to achieve:

When creating a new category, the parent category can be selected from all categories or not selected

When editing a category, the currently edited category cannot be selected as the parent category. . . If you choose yourself, the parent category will be yourself, and something will go wrong!

The implementation code is as follows, I will paste all the code of the form

<&#63;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 $form yii\widgets\ActiveForm */
&#63;>
<div class="category-form">
  <div class="row">
    <&#63;php
    if (!$model->isNewRecord) {//如果是编辑分类
      $cate = ArrayHelper::map(Category::find()->andWhere('id != :id', [':id' => $model->id])->all(), 'id', 'title');
    } else {//如果是新建分类
      $cate = ArrayHelper::map(Category::find()->all(), 'id', 'title');
    }
    &#63;>
    <div class="col-md-6 col-md-offset-3">
      <&#63;php $form = ActiveForm::begin(); &#63;>
      <&#63;= $form->field($model, 'title')->textInput(['maxlength' => 100])->label("分类标题") &#63;>
      <&#63;= $form->field($model, 'name')->textInput(['maxlength' => 100])->label("分类别名") &#63;>
      <&#63;= $form->field($model, 'pid')->dropDownList($cate, ['prompt' => '请选择父分类'])->label("父分类") &#63;>
      <&#63;= $form->field($model, 'keywords')->textarea(['maxlength' => 255])->label("分类关键词") &#63;>
      <&#63;= $form->field($model, 'description')->textarea(['maxlength' => 255])->label("分类描述") &#63;>
      <div class="form-group">
        <div class="row">
          <div class="col-md-6 col-md-offset-3">
            <&#63;= Html::submitButton($model->isNewRecord &#63; '创建' : '更新', ['class' => $model->isNewRecord &#63; 'btn btn-block btn-success' : 'btn btn-block btn-primary']) &#63;>
          </div>
        </div>
      </div>
      <&#63;php ActiveForm::end(); &#63;>
    </div>
  </div>
</div>

Readers who are interested in more Yii-related content can check out the special topics of this site: "Introduction to Yii Framework and Summary of Common Techniques", "Summary of Excellent Development Framework of PHP", "Basic Tutorial for Getting Started with Smarty Templates", "Introduction to PHP Object-Oriented Programming" Tutorial", "php string (string) usage summary", "php+mysql database operation introductory tutorial" and "php common database operation skills summary"

I hope this article will help you design PHP programs based on the Yii framework.