报错:Using $this when not in object context. 模型类用gii生成,原文如下:

<?php

namespace app\models;

use Yii;

/**
 * This is the model class for table "resources".
 *
 * @property integer $internalid
 * @property integer $resourcetype
 * @property string $publicid
 * @property integer $parentid
 *
 * @property Attachedfiles[] $attachedfiles
 * @property Changes[] $changes
 * @property Dicomidentifiers[] $dicomidentifiers
 * @property Maindicomtags[] $maindicomtags
 * @property Metadata[] $metadatas
 * @property Patientrecyclingorder[] $patientrecyclingorders
 * @property Resources $parent
 * @property Resources[] $resources
 */
class Resources extends \yii\db\ActiveRecord
{
    /**
     * @inheritdoc
     */
    public static function tableName()
    {
        return 'resources';
    }

    /**
     * @return \yii\db\Connection the database connection used by this AR class.
     */
    public static function getDb()
    {
        return Yii::$app->get('db2');
    }

    /**
     * @inheritdoc
     */
    public function rules()
    {
        return [
            [['resourcetype', 'publicid'], 'required'],
            [['resourcetype', 'parentid'], 'integer'],
            [['publicid'], 'string', 'max' => 64],
            [['parentid'], 'exist', 'skipOnError' => true, 'targetClass' => Resources::className(), 'targetAttribute' => ['parentid' => 'internalid']],
        ];
    }

    /**
     * @inheritdoc
     */
    public function attributeLabels()
    {
        return [
            'internalid' => 'Internalid',
            'resourcetype' => 'Resourcetype',
            'publicid' => 'Publicid',
            'parentid' => 'Parentid',
        ];
    }

    /**
     * @return \yii\db\ActiveQuery
     */
    public function getAttachedfiles()
    {
        return $this->hasMany(Attachedfiles::className(), ['id' => 'internalid']);
    }
}