feat: introduce the depth attribute (#281)

Author: franzose

src/Entity.php

@@ -7,6 +7,7 @@
 use Illuminate\Database\Eloquent\Model as Eloquent;
 use Illuminate\Database\Eloquent\Relations\BelongsTo;
 use Illuminate\Database\Eloquent\Relations\HasMany;
+use Illuminate\Database\Eloquent\Relations\HasOne;
 use Illuminate\Database\Eloquent\SoftDeletes;
 use Franzose\ClosureTable\Scope\Ancestor;
 use Franzose\ClosureTable\Scope\DirectChild;
@@ -23,8 +24,9 @@
  * However, if you named, for example, the position column to be "pos",
  * remember you can get its value either by $this->pos or $this->position.
  *
- * @property int position Alias for the current position attribute name
+ * @property int|null position Alias for the current position attribute name
  * @property mixed parent_id Alias for the direct ancestor identifier attribute name
+ * @property int|null depth Current node depth
  * @property EntityCollection children Child nodes loaded from the database
  */
 class Entity extends Eloquent
@@ -35,6 +37,7 @@ class Entity extends Eloquent
     use DirectChild;
     use Sibling;
 
+    private const DEPTH_RELATION_NAME = 'closureDepth';
     public const CHILDREN_RELATION_NAME = 'children';
 
     /**
@@ -69,6 +72,15 @@ class Entity extends Eloquent
      */
     public $timestamps = false;
 
+    /**
+     * The relations to eager load on every query.
+     *
+     * @var string[]
+     */
+    protected $with = [
+        self::DEPTH_RELATION_NAME,
+    ];
+
     /**
      * Entity constructor.
      */
@@ -182,6 +194,42 @@ public function getPositionColumn(): string
         return 'position';
     }
 
+    /**
+     * Returns the closure row with the max depth for the current node.
+     *
+     * @internal
+     */
+    public function closureDepth(): HasOne
+    {
+        $relatedClass = get_class($this->closure);
+        $descendantColumn = $this->closure->getDescendantColumn();
+        $depthColumn = $this->closure->getDepthColumn();
+
+        $relation = $this->hasOne($relatedClass, $descendantColumn, $this->getKeyName());
+        $relation->getRelated()->setTable($this->closure->getTable());
+
+        return $relation->ofMany($depthColumn, 'max');
+    }
+
+    /**
+     * Gets the current node depth.
+     */
+    public function getDepthAttribute(): ?int
+    {
+        if (!$this->exists) {
+            return null;
+        }
+
+        if ($this->relationLoaded(static::DEPTH_RELATION_NAME)) {
+            $depth = $this->getRelation(static::DEPTH_RELATION_NAME)?->getAttribute($this->closure->getDepthColumn());
+            return $depth !== null ? (int) $depth : 0;
+        }
+
+        $depth = $this->closureDepth()->value($this->closure->getDepthColumn());
+
+        return $depth !== null ? (int) $depth : 0;
+    }
+
     /**
      * Checks if the current model table has the given column.
      */

tests/Entity/DepthTests.php

@@ -0,0 +1,56 @@
+<?php
+declare(strict_types=1);
+
+namespace Franzose\ClosureTable\Tests\Entity;
+
+use Franzose\ClosureTable\Entity;
+use Franzose\ClosureTable\Tests\BaseTestCase;
+
+class DepthTests extends BaseTestCase
+{
+    public function testDepthAccessorUsesEagerLoadedRelation(): void
+    {
+        $expected = [
+            9 => 0,
+            10 => 1,
+            11 => 2,
+            12 => 3,
+            13 => 1,
+            14 => 1,
+            15 => 1,
+        ];
+
+        $entities = Entity::whereIn('id', array_keys($expected))->get();
+
+        foreach ($expected as $id => $depth) {
+            $entity = $entities->firstWhere('id', $id);
+
+            static::assertNotNull($entity);
+            static::assertTrue($entity->relationLoaded('closureDepth'));
+            static::assertEquals($depth, $entity->depth);
+        }
+    }
+
+    public function testDepthUpdatesAfterMove(): void
+    {
+        $entity = Entity::find(12);
+        $entity->moveTo(0, 13);
+
+        $entity = Entity::find(12);
+
+        static::assertEquals(2, $entity->depth);
+    }
+
+    public function testDepthForCreatedEntityWithoutRelationLoaded(): void
+    {
+        $entity = Entity::create(['title' => 'abcde']);
+
+        static::assertFalse($entity->relationLoaded('closureDepth'));
+        static::assertEquals(0, $entity->depth);
+    }
+
+    public function testDepthForUnsavedEntityIsNull(): void
+    {
+        static::assertNull((new Entity())->depth);
+    }
+}