Object of class could not be converted to string

Hi, I’m Having this problem that I couldn’t find a solution after the data save to my table I get this error message

“Object of class app\models\ChnMember could not be converted to string” for 3 days I couldn’t find how to solve it, the data are saved to my table but All i get is that error message:

my app\models\ChnMember:


class ChnMember extends \yii\db\ActiveRecord

{

    /**

     * @inheritdoc

     */

    public static function tableName()

    {

        return 'chn_member';

    }


    /**

     * @inheritdoc

     */

    public function rules()

    {

        return [

            [['user_id', 'channel_id', 'chnmembertype_id'], 'required'],

            [['user_id', 'channel_id'], 'integer'],

            [['member_type', 'member_note'], 'string', 'max' => 100],

            [['chnmembertype_id'], 'string', 'max' => 20],

            [['user_id', 'channel_id', 'chnmembertype_id'], 'unique', 'targetAttribute' => ['user_id', 'channel_id', 'chnmembertype_id']],

            [['channel_id'], 'exist', 'skipOnError' => true, 'targetClass' => Channel::className(), 'targetAttribute' => ['channel_id' => 'channel_id']],

            [['chnmembertype_id'], 'exist', 'skipOnError' => true, 'targetClass' => ChnmemberType::className(), 'targetAttribute' => ['chnmembertype_id' => 'chnmembertype_id']],

            [['user_id'], 'exist', 'skipOnError' => true, 'targetClass' => User::className(), 'targetAttribute' => ['user_id' => 'user_id']],

        ];

    }


    /**

     * @inheritdoc

     */

    public function attributeLabels()

    {

        return [

            'member_type' => Yii::t('app', 'Member Type'),

            'member_note' => Yii::t('app', 'Member Note'),

            'user_id' => Yii::t('app', 'User ID'),

            'channel_id' => Yii::t('app', 'Channel ID'),

            'chnmembertype_id' => Yii::t('app', 'Chnmembertype ID'),

        ];

    }


    /**

     * @return \yii\db\ActiveQuery

     */

    public function getChannel()

    {

        return $this->hasOne(Channel::className(), ['channel_id' => 'channel_id']);

    }


    /**

     * @return \yii\db\ActiveQuery

     */

    public function getChnmembertype()

    {

        return $this->hasOne(ChnmemberType::className(), ['chnmembertype_id' => 'chnmembertype_id']);

    }


    /**

     * @return \yii\db\ActiveQuery

     */

    public function getUser()

    {

        return $this->hasOne(User::className(), ['user_id' => 'user_id']);

    }


    /**

     * @inheritdoc

     * @return \app\queries\ChnMemberQuery the active query used by this AR class.

     */

    public static function find()

    {

        return new \app\queries\ChnMemberQuery(get_called_class());

    }

}

I created a file name "AxChnMemJoin" :


<?php


namespace app\accions\chnmem;


use Yii;

use app\models\ChnMember;


class AxChnMemJoin

{

	public function ChannelMember($CHNID)

	{

		return ChnMember::findOne(['user_id' => Yii::$app->user->id, 'channel_id' => $CHNID]);

	}

	

	public function JoinChannel($CHNID)

	{

		$MCHNMEM = new ChnMember;

		$MCHNMEM->user_id = Yii::$app->user->id;

		$MCHNMEM->channel_id = $CHNID;

		$MCHNMEM->chnmembertype_id = '100';

		$MCHNMEM->member_type = 'Member';

		$MCHNMEM->member_note = '100';

		

		$MCHNMEM->save();

	}

	

	public function LeaveChannel($CHNID)

	{

		$this->ChannelMember($CHNID)->delete();

	}

}


?>

Then I call this file from a widget "ChannelHeaderWidget"


<?php 


namespace app\components\Channel\ViewContent;


use Yii;

use yii\base\Widget;

use yii\helpers\Html;


use app\models\Channel;

use app\accions\chnmem\AxChnMemJoin;


class ChannelHeaderWidget extends \yii\base\Widget {

	

	public $chn_id;

	

    public function run()

	{

		$modelHDR = Channel::findOne($this->chn_id);	$acc_ChnMem = new AxChnMemJoin;

		

		$isMember = $acc_ChnMem->ChannelMember($modelHDR->channel_id);

		

		// JOIN CHANNEL

		if (Yii::$app->request->post('value') == 'JoinChannel')

		{

			$acc_ChnMem->JoinChannel($modelHDR->channel_id);

		}


		// LEAVE CHANNEL

		if (Yii::$app->request->post('value') == 'LeaveChannel')

		{

			$acc_ChnMem->LeaveChannel($modelHDR->channel_id);

		}

		

        return $this->render('/chn/chn-header', [

			'modelHDR' => $modelHDR,

			'isMember' => $isMember,

        ]);

    }

	

}


?>

and my view "/chn/chn-header"


<?php


use yii\helpers\Html;

use yii\helpers\Url; // URL HOME


/* @var $this yii\web\View */

/* @var $modelHDR app\models\Channel */


$this->title = $modelHDR->channel_title;

?>


<header class="top channel-header" style="background: url('<?=Url::home().$modelHDR->channel_bgimage?>') no-repeat;">	

	

	<div class="title-chn row">

		<div class="col-xs-4">

			<img class="img-circle" src="<?=Url::home().$modelHDR->user->user_thavatar?>" height="70" width="70">

		</div>

		

		<div class="col-xs-16">

			<h2 class="title"><?= $modelHDR->channel_title ?></h2>

			<h3 class="title hidden-xs"><?= $modelHDR->channel_subject ?></h3>

		</div>

		

		<div class="col-xs-4 text-right" style="padding:15px">

			<?php if(Yii::$app->user->id){ ?>

				<?php if($modelHDR->user_id == Yii::$app->user->id){ ?>

				<button type="button" class="btn btn-info btn-lg" data-toggle="modal" data-target="#ModalEdit">Edit</button>

				<?php } ?>

				

				<?php if($modelHDR->user_id !== Yii::$app->user->id){ ?>

					<?= $this->render('/chn-mem/Join-Leave', [

							'modelHDR'	=> $modelHDR, 

							'isMember'	=> $isMember,

						])

					?>

				<?php } ?>

			<?php } ?>

		</div>

	</div>

	

</header>