# Nested Sets Behavior for Yii 2

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A modern nested sets behavior for the Yii framework utilizing the Modified Preorder Tree Traversal algorithm.

## Installation

The preferred way to install this extension is through [composer](http://getcomposer.org/download/).

Either run

```bash
$ php composer.phar require creocoder/yii2-nested-sets:dev-master
```

or add

```
"creocoder/yii2-nested-sets": "dev-master"
```

to the `require` section of your `composer.json` file.

## Configuring

First you need to configure model as follows:

```php
use creocoder\nestedsets\NestedSetsBehavior;

class Tree extends \yii\db\ActiveRecord
{
    public function behaviors() {
        return [
            NestedSetsBehavior::className(),
        ];
    }

    public function transactions()
    {
        return [
            self::SCENARIO_DEFAULT => self::OP_ALL,
        ];
    }

    public static function find()
    {
        return new TreeQuery(get_called_class());
    }
}
```

Second you need to configure query model as follows:

```php
use creocoder\nestedsets\NestedSetsQueryBehavior;

class TreeQuery extends \yii\db\ActiveQuery
{
    public function behaviors() {
        return [
            NestedSetsQueryBehavior::className(),
        ];
    }
}
```

## Usage

### Quick Example
#### Making a root node

```php
$countries = new Menu(['name' => 'Countries']);
$countries->makeRoot();
```

#### Make a node as the last child of another node

```php
$australia = new Menu(['name' => 'Australia']);
$australia->appendTo($countries);
```

The tree will look like this
```
- Countries
    - Australia
```

#### Make a node as the first child of another node

```php
$russia = new Menu(['name' => 'Russia']);
$russia->prependTo($countries);
```

The tree will look like this
```
- Countries
    - Russia
    - Australia
```

#### Append a node before another node

```php
$newZeeland = new Menu(['name' => 'New Zeeland']);
$newZeeland->insertBefore($australia);
```

The tree will look like this
```
- Countries
    - Russia
    - New Zeeland
    - Australia
```

#### Append a node after another node

```php
$newZeeland = new Menu(['name' => 'New Zeeland']);
$newZeeland->insertBefore($australia);
```

The tree will look like this
```
- Countries
    - Russia
    - New Zeeland
    - Australia
```

#### Append a node before another node

```php
$argentina = new Menu(['name' => 'Argentina']);
$argentina->insertAfter($australia);
```

The tree will look like this
```
- Countries
    - Russia
    - New Zeeland
    - Australia
    - Argentina
```