Strategi must be a string - yii2

Question

please help me..
when data input arises such problems "Strategi must be a string."
this is my controller :
$isistrategi = $_POST['FormNarasi'];
$fn = FormNarasi::find()->where([
'kriteria_id' => $model->id,
'form_spmi_id' => $formSpmi->id,
])->one();
if(empty($fn))
$fn = new FormNarasi;
$fn->kriteria_id = $model->id;
$fn->form_spmi_id = $formSpmi->id;
$fn->strategi = $isistrategi;
this is my _form :
<?php
$fn = FormNarasi::find()->where([
'kriteria_id' => $model->id,
'form_spmi_id' => $formSpmi->id
])->one();
echo $form->field($fn, 'strategi')->widget(CKEditor::className(), [
'options' => ['rows' => 6],
'preset' => 'advance'
])
?>
<div class="form-group">
<?= Html::submitButton('Save', ['class' => 'btn btn-success','value'=>'1','name'=>'btn-submit']) ?>
</div>
<?php ActiveForm::end(); ?>
please help, master

Answer 1

Here you are assigning an array to the model
$isistrategi = $_POST['FormNarasi'];
...
$fn->strategi = $isistrategi; // HERE
and in the following code you are accessing it. There is an array assigned. So you should assign there a string (the content of the CKEditor)
echo $form->field($fn, 'strategi')->widget(CKEditor::className(), [ // HERE
...
])
As #Sfili_81 mentioned, do not access the $_POST directly and rather use $model->load(Yii::$app->request->post())