Introduction

This Laravel Eloquent extension provides recursive relationships using common table expressions (CTE).

Supports Laravel 5.5.29+.

Compatibility

• MySQL 8.0+
• MariaDB 10.2+
• PostgreSQL 9.4+
• SQLite 3.8.3+
• SQL Server 2008+

Installation

composer require staudenmeir/laravel-adjacency-list:"^1.0"

Usage

• Getting Started
• Relationships
• Tree
• Filters
• Order
• Depth
• Path

Getting Started

Consider the following table schema for hierarchical data:

Schema::create('users', function (Blueprint $table) {
    $table->increments('id');
    $table->unsignedInteger('parent_id')->nullable();
});

Use the HasRecursiveRelationships trait in your model to work with recursive relationships:

class User extends Model
{
    use \Staudenmeir\LaravelAdjacencyList\Eloquent\HasRecursiveRelationships;
}

By default, the trait expects a parent key named parent_id. You can customize it by overriding getParentKeyName():

class User extends Model
{
    use \Staudenmeir\LaravelAdjacencyList\Eloquent\HasRecursiveRelationships;
    
    public function getParentKeyName()
    {
        return 'parent_id';
    }
}

By default, the trait uses the model's primary key as the local key. You can customize it by overriding getLocalKeyName():

class User extends Model
{
    use \Staudenmeir\LaravelAdjacencyList\Eloquent\HasRecursiveRelationships;
    
    public function getLocalKeyName()
    {
        return 'id';
    }
}

Relationships

The trait provides various relationships:

• ancestors(): The model's recursive parents.
• ancestorsAndSelf(): The model's recursive parents and itself.
• children(): The model's direct children.
• childrenAndSelf(): The model's direct children and itself.
• descendants(): The model's recursive children.
• descendantsAndSelf(): The model's recursive children and itself.
• parent(): The model's direct parent.
• parentAndSelf(): The model's direct parent and itself.
• siblings(): The parent's other children.
• siblingsAndSelf(): All the parent's children.

$ancestors = User::find($id)->ancestors;

$users = User::with('descendants')->get();

$users = User::whereHas('siblings', function ($query) {
    $query->where('name', '=', 'John');
})->get();

$total = User::find($id)->descendants()->count();

User::find($id)->descendants()->update(['active' => false]);

User::find($id)->siblings()->delete();

Tree

The trait provides the tree() query scope to get all models, beginning at the root(s):

$tree = User::tree()->get();

Filters

The trait provides query scopes to filter models by their position in the tree:

• hasChildren(): Models with children.
• hasParent(): Models with a parent.
• isLeaf(): Models without children.
• isRoot(): Models without a parent.

$noLeaves = User::hasChildren()->get();

$noRoots = User::hasParent()->get();

$leaves = User::isLeaf()->get();

$roots = User::isRoot()->get();

Order

The trait provides query scopes to order models breadth-first or depth-first:

• breadthFirst(): Get siblings before children.
• depthFirst(): Get children before siblings.

$tree = User::tree()->breadthFirst()->get();

$descendants = User::find($id)->descendants()->depthFirst()->get();

Depth

The results of ancestor, descendant and tree queries include an additional depth column.

It contains the model's depth relative to the query's parent. The depth is positive for descendants and negative for ancestors:

$descendantsAndSelf = User::find($id)->descendantsAndSelf()->depthFirst()->get();

echo $descendantsAndSelf[0]->depth; // 0
echo $descendantsAndSelf[1]->depth; // 1
echo $descendantsAndSelf[2]->depth; // 2

You can customize the column name by overriding getDepthName():

class User extends Model
{
    use \Staudenmeir\LaravelAdjacencyList\Eloquent\HasRecursiveRelationships;

    public function getDepthName()
    {
        return 'depth';
    }
}

You can use the whereDepth() query scope to filter models by their relative depth:

$descendants = User::find($id)->descendants()->whereDepth(2)->get();

$descendants = User::find($id)->descendants()->whereDepth('<', 3)->get();

Path

The results of ancestor, descendant and tree queries include an additional path column.

It contains the dot-separated path of local keys from the query's parent to the model:

$descendantsAndSelf = User::find(1)->descendantsAndSelf()->depthFirst()->get();

echo $descendantsAndSelf[0]->path; // 1
echo $descendantsAndSelf[1]->path; // 1.2
echo $descendantsAndSelf[2]->path; // 1.2.3

You can customize the column name and the separator by overriding the respective methods:

class User extends Model
{
    use \Staudenmeir\LaravelAdjacencyList\Eloquent\HasRecursiveRelationships;

    public function getPathName()
    {
        return 'path';
    }

    public function getPathSeparator()
    {
        return '.';
    }
}

Contributing

Please see CONTRIBUTING and CODE OF CONDUCT for details.