创建时提示

controller

use yii\helpers\ArrayHelper;
public function actionCreate()
    {
        $model = new Customer();
        if ($model->load(Yii::$app->request->post()) && $model->save()) {
            return $this->redirect(['view', 'id' => $model->customer_id]);
        } else {
            $addresses = Address::find()->all();
            $addresses = ArrayHelper::map($addresses,'address_id','address');
            return $this->render('create', [
                'model' => $model,
                'addresses' =>$addresses,
            ]);
        }
    }

修改时默认选中

controller

    public function actionCreate()
    {
        $model = new Customer();

        if ($model->load(Yii::$app->request->post()) && $model->save()) {
            return $this->redirect(['view', 'id' => $model->customer_id]);
        } else {
            $addresses = Address::find()->all();
            $addresses = ArrayHelper::map($addresses,'address_id','address');
            return $this->render('create', [
                'model' => $model,
                'addresses' =>$addresses,
            ]);
        }
    }

共用 view

<?= $form->field($model,'address_id')->dropDownList($addresses,
            ['prompt'=>'请选择下面的一项'],
            ['options' =>
                [
                    $model->address_id => ['selected' => true]
                ]
            ]
        ) ?>