Delete unused tags

app/Http/Controllers/FoodController.php

@@ -87,17 +87,7 @@ class FoodController extends Controller
         }
 
         $food->fill($attributes)->save();
-
-        $tags = $request->get('tags', []);
-        if (!empty($tags)) {
-            $food->syncTags(explode(',', $tags));
-        }
-        elseif ($food->tags->isNotEmpty()) {
-            $food->detachTags($food->tags);
-        }
-
-        // Refresh and index updated tags.
-        $food->fresh()->searchable();
+        $food->updateTagsFromRequest($request);
 
         session()->flash('message', "Food {$food->name} updated!");
         return redirect()->route('foods.show', $food);

app/Http/Controllers/RecipeController.php

@@ -216,17 +216,7 @@ class RecipeController extends Controller
                 $this->updateIngredients($recipe, $input);
                 $this->updateIngredientSeparators($recipe, $input);
                 $this->updateSteps($recipe, $input);
-
-                $tags = $request->get('tags', []);
-                if (!empty($tags)) {
-                    $recipe->syncTags(explode(',', $tags));
-                }
-                elseif ($recipe->tags->isNotEmpty()) {
-                    $recipe->detachTags($recipe->tags);
-                }
-
-                // Refresh and index updated tags.
-                $recipe->fresh()->searchable();
+                $recipe->updateTagsFromRequest($request);
             });
         } catch (\Exception $e) {
             DB::rollBack();

app/Models/Food.php

@@ -73,6 +73,7 @@ use Illuminate\Database\Eloquent\Model;
  * @method static \Illuminate\Database\Eloquent\Builder|Food withUniqueSlugConstraints(\Illuminate\Database\Eloquent\Model $model, string $attribute, array $config, string $slug)
  * @method static \Database\Factories\FoodFactory factory(...$parameters)
  * @property-read \Illuminate\Support\Collection $units_supported
+ * @property-read string $ingredient_id
  */
 final class Food extends Model
 {

app/Models/Recipe.php

@@ -82,6 +82,7 @@ use Spatie\MediaLibrary\MediaCollections\Models\Media;
  * @property float|null $volume
  * @property-read string|null $volume_formatted
  * @method static \Illuminate\Database\Eloquent\Builder|Recipe whereVolume($value)
+ * @property-read string $ingredient_id
  */
 final class Recipe extends Model implements HasMedia
 {

app/Models/Tag.php

@@ -3,6 +3,7 @@
 namespace App\Models;
 
 use Illuminate\Database\Eloquent\Factories\HasFactory;
+use Illuminate\Database\Eloquent\Relations\MorphToMany;
 use Spatie\Tags\Tag as TagBase;
 
 /**
@@ -31,8 +32,26 @@ use Spatie\Tags\Tag as TagBase;
  * @method static \Illuminate\Database\Eloquent\Builder|Tag whereUpdatedAt($value)
  * @method static Builder|Tag withType(?string $type = null)
  * @mixin \Eloquent
+ * @property-read \Illuminate\Database\Eloquent\Collection|\App\Models\Food[] $foods
+ * @property-read int|null $foods_count
+ * @property-read \Illuminate\Database\Eloquent\Collection|\App\Models\Recipe[] $recipes
+ * @property-read int|null $recipes_count
  */
 final class Tag extends TagBase
 {
     use HasFactory;
+
+    /**
+     * Get all foods related to this tag.
+     */
+    public function foods(): MorphToMany {
+        return $this->morphedByMany(Food::class, 'taggable');
+    }
+
+    /**
+     * Get all recipes related to this tag.
+     */
+    public function recipes(): MorphToMany {
+        return $this->morphedByMany(Recipe::class, 'taggable');
+    }
 }

app/Models/Traits/Taggable.php

@@ -4,6 +4,7 @@ namespace App\Models\Traits;
 
 use App\Models\Tag;
 use Illuminate\Database\Eloquent\Relations\MorphToMany;
+use Illuminate\Http\Request;
 use Spatie\Tags\HasTags;
 
 trait Taggable
@@ -27,4 +28,29 @@ trait Taggable
             ->morphToMany(self::getTagClassName(), 'taggable', 'taggables', null, 'tag_id')
             ->orderBy('order_column');
     }
+
+    /**
+     * Updates tags from a request with a "tags" parameter value for any bag.
+     */
+    public function updateTagsFromRequest(Request $request): void {
+        $tags_original = $this->tags;
+
+        $tags = $request->get('tags', []);
+        if (!empty($tags)) {
+            $this->syncTags(explode(',', $tags));
+        }
+        elseif ($this->tags->isNotEmpty()) {
+            $this->detachTags($this->tags);
+        }
+
+        // Refresh and index updated tags.
+        $this->refresh()->searchable();
+
+        // Delete any removed tags that are no longer in use.
+        $tags_original->diff($this->tags)->each(function (Tag $tag) {
+            if ($tag->foods->isEmpty() && $tag->recipes->isEmpty()) {
+                $tag->delete();
+            }
+        });
+    }
 }