Nesting Comments Yii2 - activerecord

Question

I have a comment table, like below:
+-----------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-----------+--------------+------+-----+---------+----------------+
| id | int(11) | NO | PRI | NULL | auto_increment |
| user_id | int(11) | NO | | NULL | |
| parent_id | int(11) | NO | | 0 | |
| post_id | int(11) | NO | | NULL | |
| body | text | NO | | NULL | |
| date | datetime | NO | | NULL | |
| status | tinyint(1) | NO | | 0 | |
+-----------+--------------+------+-----+---------+----------------+
Comment parent_id by defautl is 0, if comment is answered, parent id insert in parent_id column.
And make a relation with User Table with below code:
public function getPosts()
{
return $this->hasMany(Post::className(), ['category_id' => 'id']);
}
How can i show nesting?

Answer 1

First, you need to define the relation inside your Comment model class:
public function getChildComments()
{
return $this->hasMany(self::className(), ['parent_id' => 'id']);
}
That defines the entity relationship to itself. I think it is always good to also keep related logic or handlers into helper/callable methods in the same class in a way that doesn't require having to load them all at once from database. What comes next should answer the question:
How can i show nesting?
CASE01: Inside a RESTFul application
Simply override fields() inside Comment class to always output child comments:
public function fields()
{
$fields = parent::fields();
$fields['childs'] = 'childComments';
return $fields;
}
That's it. yii\rest\Serializer should take care of the recursive representation and you'll get something similar to this when outputting a list of comments:
CASE02: Inside a HTML web view
There is probably many ways to achieve it. The easiest and cleanest way I could think of is to tie on the template engine that Yii is already using to re-render the view holding child comments in a recursive way. As a working example, add something like what follows to your index.php file:
<?php
use yii\helpers\Html;
use yii\widgets\ListView;
use yii\data\ActiveDataProvider;
use app\models\Comment;
?>
<?= ListView::widget([
'dataProvider' => new ActiveDataProvider([
'query' => Comment::find(),
]),
'itemView' => '_comment',
'itemOptions' => ['style' => 'padding: 10px 50px; border: 1px solid red'],
]); ?>
Then create that _comment.php file:
<?php
use yii\helpers\Html;
use yii\widgets\ListView;
use yii\data\ActiveDataProvider;
?>
<div style="background-color: skyblue; padding: 5px 15px">
<h4><?= Html::encode($model->id) ?></h4>
<p><?= Html::encode($model->name) ?></p>
</div>
<?php
if ($model->getChildComments()->count()) {
echo ListView::widget([
'dataProvider' => new ActiveDataProvider([
'query' => $model->getChildComments(),
]),
'itemView' => '_comment',
'itemOptions' => ['style' => 'padding: 10px 0 10px 50px; border: 1px dotted blue'],
]);
}
?>
The template will create a new instance of itself each time it finds childComments linked to the represented one. With that bit of CSS paddings to show the nesting, that code should output this: