How to save related models to database?

Question

Yii

Please help me I can't save the record to the database.
I do not know how exactly to formulate the essence of the problem, but I will try to explain it to you.
I want to save records to db using dynamic forms. here is the link https://github.com/unclead/yii2-multiple-input
I do it through the link. what scheme? I have a goal and the goal can have its own data and also an unlimited number of stages.
Here is what I write in the widget.

<?= \unclead\multipleinput\MultipleInput::widget([
    'model'=>$model,
    'attribute'=>'stages',
])

these are two important arguments.
and it gives me this in the input in the name attribute . I need the stage to start with a capital letter. Otherwise it doesn't save stges. Please tell me how to do it? ps
Goals[stages][0][title]

Model

<?php

namespace app\models;

use Yii;
use yii\db\ActiveRecord;
use app\components\MathHelper;

/**
 * This is the model class for table "goals".
 *
 * @property int $id
 * @property string $goal
 * @property string $date_finish_goal
 * @property string $criterion_fifnish_goal
 * @property int $id_user
 * @property int $category_goal
 * @property int $priority_goal
 * @property int $status
 * @property int $is_public
 * @property string $need_goal
 * @property string $doc
 *
 * @property CriteriesGoals $categoryGoal
 * @property Users $user
 * @property Stages[] $Stages
 */
class Goals extends ActiveRecord
{
    /**
     * @inheritdoc
     */
    public static function tableName()
    {
        return 'goals';
    }

    /**
     * @inheritdoc
     */
    public function rules()
    {
        return [
            [['goal', 'date_finish_goal', 'criterion_fifnish_goal', 'id_user','priority_goal', 'is_public', 'need_goal', 'category_goal'], 'required', 'message'=>'Поле обязательное для заполнения'],
            [['date_finish_goal'], 'safe'],
            [['id_user', 'category_goal', 'priority_goal', 'status', 'is_public'], 'integer'],
            [['goal', 'criterion_fifnish_goal', 'need_goal'], 'string', 'max' => 255],
            [['category_goal'], 'exist', 'skipOnError' => true, 'targetClass' => CriteriesGoals::className(), 'targetAttribute' => ['category_goal' => 'id']],
            [['id_user'], 'exist', 'skipOnError' => true, 'targetClass' => Users::className(), 'targetAttribute' => ['id_user' => 'id']],
      [['doc'], 'file', 'skipOnEmpty' => true, 'extensions' => 'png, jpg, gif, jpeg'],
        ];
    }

  public function afterSave($insert, $changedAttributes){
    parent::afterSave($insert, $changedAttributes);
    if($insert)
    {
      $news = new News();
      $news->id_user = $this->id_user;
      $news->id_goal = $this->id;
      $news->date_create = date('Y-m-d H:i:s');
      $news->save();
    }
  }

    /**
     * @inheritdoc
     */
    public function attributeLabels()
    {
        return [
            'id' => 'ID',
            'goal' => 'Goal',
            'date_finish_goal' => 'Date Finish Goal',
            'criterion_fifnish_goal' => 'Criterion Fifnish Goal',
            'id_user' => 'Id User',
            'category_goal' => 'Category Goal',
            'priority_goal' => 'Priority Goal',
            'status' => 'Status',
            'is_public' => 'Is Public',
            'need_goal' => 'Need Goal',
            'doc' => 'Doc',
        ];
    }

    /**
     * @return \yii\db\ActiveQuery
     */
    public function getCategoryGoal()
    {
        return $this->hasOne(CriteriesGoals::className(), ['id' => 'category_goal']);
    }

    public function getPriorityGoal()
    {
        return $this->hasOne(PrioritiesGoals::className(), ['id' => 'priority_goal']);
    }

    /**
     * @return \yii\db\ActiveQuery
     */
    public function getUser()
    {
        return $this->hasOne(Users::className(), ['id' => 'id_user']);
    }

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

    public function getReports()
    {
        return $this->hasMany(News::className(), ['id_goal' => 'id'])->andWhere(['section'=>'report'])->orderBy(['id'=>SORT_DESC]);
    }
  
  /**
     * @return \yii\db\ActiveQuery
     */
    public function getSubstages()
    {
        return $this->hasMany(Substage::className(), ['id_stage' => 'goal_id']);
    }


    public static function getCountGoals(array $params=[])
    {
        $allCount = self::find()->where(['id_user'=>Yii::$app->user->id])->count();
        if($params['status'])
        {
            $count = self::find()->where(['status'=>$params['status'],'id_user'=>Yii::$app->user->id])->count();
            $results = [
                'count'=>$count,
                'procent'=>MathHelper::getProcent(['number'=>$count,'fromNumber'=>$allCount]),
            ];
        }else{
            $results = [
                'count'=>$allCount,
            ];
        }

        return $results;
    }

    public static function getSelectGoals()
    {
        return self::find()->select(['id','goal'])->where(['id_user'=>Yii::$app->user->id])->asArray()->all();
    }

}

Action

public function actionUpdate($id)
    {
        $model = $this->findModel($id);
        $Stages = $model->Stages;
        //$Substages = [new Substage];

        if ($model->load(Yii::$app->request->post())) {

      $model->doc = UploadedFile::getInstance($model, 'doc');
            if ($model->doc) {
                Yii::$app->storage->deleteUploadedFile($model->oldAttributes['doc']);
                $model->doc = Yii::$app->storage->saveUploadedFile($model->doc);
            }else{
                $model->doc = $model->oldAttributes['doc'];
            }
      if($model->save())
      {
                if(Model::loadMultiple($Stages, Yii::$app->request->post('Goals')))
                {
                    foreach ($Stages as $key => $Stage) {
                        $Stage->save(false);
                    }
                }
            }
        }

        return $this->render('update', [
            'model' => $model,
        ]);
    }

Answer 1

Good afternoon.
Do you use this widget in ActiveForm?
If so, would it be better to use it like this?

echo $form->field($model, 'stages')->widget(MultipleInput::className(), [
    'model' => $model,
    'attribute' => 'stages',
])
->label(false);

ps Yes, and it would not hurt to see how you save models.