Yii 2 редактируемое дерево категорий

1. установим расширение

composer require --prefer-dist leandrogehlen/yii2-treegrid "*"

2. DDL таблицы

CREATE TABLE `tree` (
  `id` INTEGER(11) NOT NULL AUTO_INCREMENT,
  `name` VARCHAR(255) COLLATE utf8_general_ci NOT NULL COMMENT 'имя',
  `url` VARCHAR(255) COLLATE utf8_general_ci DEFAULT NULL COMMENT 'путь',
  `tree_id` INTEGER(11) DEFAULT NULL COMMENT 'предок',
  PRIMARY KEY (`id`) USING BTREE,
  UNIQUE KEY `id` (`id`) USING BTREE,
  UNIQUE KEY `name` (`name`) USING BTREE,
  UNIQUE KEY `url` (`url`) USING BTREE,
  KEY `tree_id` (`tree_id`) USING BTREE,
  CONSTRAINT `treee_fk1` FOREIGN KEY (`tree_id`) REFERENCES `tree` (`id`) ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB
AUTO_INCREMENT=14 CHARACTER SET 'utf8' COLLATE 'utf8_general_ci'
;

3. \views\tree\index.php

<?php

use yii\helpers\Html;
use yii\grid\GridView;
/* * *ext** */
use leandrogehlen\treegrid\TreeGrid;

/* @var $this yii\web\View */
/* @var $searchModel app\modules\rpg\models\TreeSearch */
/* @var $dataProvider yii\data\ActiveDataProvider */

$this->title = 'Trees';
$this->params['breadcrumbs'][] = $this->title;
?>
<div class="tree-index">

    <h1><?= Html::encode($this->title) ?></h1>
    <?php // echo $this->render('_search', ['model' => $searchModel]); ?>

    <p>
        <?php
        if ($dataProvider->count == 0)
            echo Html::a('Создать корневой элемент', ['add'], ['class' => 'btn btn-success']);
        ?>
    </p>
    <?=
    TreeGrid::widget([
        'dataProvider' => $dataProvider,
        'keyColumnName' => 'id',
        'showOnEmpty' => FALSE,
        'parentColumnName' => 'tree_id',
        'columns' => [

            'name',
            ['class' => 'yii\grid\ActionColumn',
                'template' => '{view} {update} {delete} {add}',
                'buttons' => [
                    'add' => function ($url, $model, $key)
                    {
                        return Html::a('<span class="glyphicon glyphicon-plus"></span>', $url);
                    },
                ]
            ]
        ]
    ]);
    ?>

</div>

Если таблица пустая, тосоздаем корневой элемент

Создаем кнопку add для добавления потомка

4. models\Tree.php

<?php

namespace app\modules\rpg\models;

use Yii;

/**
 * This is the model class for table "tree".
 *
 * @property integer $id
 * @property string $name
 * @property string $url
 * @property integer $tree_id
 *
 * @property Tree $tree
 * @property Tree[] $trees
 */
class Tree extends \yii\db\ActiveRecord
{

    /**
     * @inheritdoc
     */
    public static function tableName()
    {
        return 'tree';
    }

    /**
     * @inheritdoc
     */
    public function rules()
    {
        return [
            [['name'], 'required'],
            [['tree_id'], 'integer'],
            [['name', 'url'], 'string', 'max' => 255],
            [['name'], 'unique'],
            [['url'], 'unique'],
            [['url'], 'default', 'value' => null],
        ];
    }

    /**
     * @inheritdoc
     */
    public function attributeLabels()
    {
        return [
            'id' => 'ID',
            'name' => 'имя',
            'url' => 'путь',
        ];
    }

    public function myname($id)
    {
        $model = Tree::find()
                        ->where(['id' => $id])
                        ->one()->name;
        return $model;
    }

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

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

}

Немного поправил правило для сохранения NULL а не пустой строки

Создал функцию для имени

5.  controllers\TreeController.php

<?php

namespace app\modules\rpg\controllers;

use Yii;
use app\modules\rpg\models\Tree;
use app\modules\rpg\models\TreeSearch;
use yii\web\Controller;
use yii\web\NotFoundHttpException;
use yii\filters\VerbFilter;

/* * *ext** */
use yii\data\ActiveDataProvider;

/**
 * TreeController implements the CRUD actions for Tree model.
 */
class TreeController extends Controller
{

    public function behaviors()
    {
        return [
            'verbs' => [
                'class' => VerbFilter::className(),
                'actions' => [
                    'delete' => ['post'],
                ],
            ],
        ];
    }

    /**
     * Lists all Tree models.
     * @return mixed
     */
    public function actionIndex()
    {
        $query = Tree::find();
        $dataProvider = new ActiveDataProvider([
            'query' => $query,
        ]);

        return $this->render('index', [
                    'dataProvider' => $dataProvider
        ]);
    }

    /**
     * Displays a single Tree model.
     * @param integer $id
     * @return mixed
     */
    public function actionView($id)
    {
        return $this->render('view', [
                    'model' => $this->findModel($id),
        ]);
    }

    /**
     * Creates a new Tree model.
     * If creation is successful, the browser will be redirected to the 'view' page.
     * @return mixed
     */
    public function actionCreate()
    {
        $model = new Tree();

        if ($model->load(Yii::$app->request->post()) && $model->save())
        {
            return $this->redirect(['view', 'id' => $model->id]);
        }
        else
        {
            return $this->render('create', [
                        'model' => $model,
            ]);
        }
    }

    public function actionAdd()
    {
        $model = new Tree();
        $model->loadDefaultValues();
        $id = Yii::$app->request->get('id');
        $model->tree_id = $id;

        if ($model->load(Yii::$app->request->post()) && $model->save())
        {
            return $this->redirect(['index']);
        }
        else
        {
            return $this->render('create', [
                        'model' => $model,
            ]);
        }
    }

    /**
     * Updates an existing Tree model.
     * If update is successful, the browser will be redirected to the 'view' page.
     * @param integer $id
     * @return mixed
     */
    public function actionUpdate($id)
    {
        $model = $this->findModel($id);

        if ($model->load(Yii::$app->request->post()) && $model->save())
        {
            return $this->redirect(['view', 'id' => $model->id]);
        }
        else
        {
            return $this->render('update', [
                        'model' => $model,
            ]);
        }
    }

    /**
     * Deletes an existing Tree model.
     * If deletion is successful, the browser will be redirected to the 'index' page.
     * @param integer $id
     * @return mixed
     */
    public function actionDelete($id)
    {
        $this->findModel($id)->delete();

        return $this->redirect(['index']);
    }

    /**
     * Finds the Tree model based on its primary key value.
     * If the model is not found, a 404 HTTP exception will be thrown.
     * @param integer $id
     * @return Tree the loaded model
     * @throws NotFoundHttpException if the model cannot be found
     */
    protected function findModel($id)
    {
        if (($model = Tree::findOne($id)) !== null)
        {
            return $model;
        }
        else
        {
            throw new NotFoundHttpException('The requested page does not exist.');
        }
    }

}

В index передаются данные для дерева

В add указывается предок

Удаление происходит каскадно за счет внешнего ключа

Исходники https://github.com/des1roer/yii2tree