Efficient Unique Slug Generation in Eloquent Without Looping Queries

Generate unique database slugs in Eloquent by querying the maximum existing numerical suffix directly instead of executing repeated queries in a while loop.

When generating URL slugs for blog posts, products, or articles, collisions occur when two records share the same title ("My First Post").

A frequent implementation uses a while loop that repeatedly queries the database (post-1, post-2, post-3, ...) until an available slug is found. On busy applications with many duplicate titles, this pattern generates dozens of sequential database roundtrips for a single record creation.

You can determine the next unique slug in a single query by inspecting the maximum numeric suffix using SQL functions.

The Efficient Implementation

namespace App\Models;

use Illuminate\Database\Eloquent\Model;
use Illuminate\Support\Facades\DB;

class Article extends Model
{
    protected static function booted(): void
    {
        static::creating(function (Article $article): void {
            if (empty($article->slug)) {
                $article->slug = static::generateUniqueSlug($article->title);
            }
        });
    }

    public static function generateUniqueSlug(string $title): string
    {
        $baseSlug = str($title)->slug()->value();

        // Check if base slug is already available
        if (static::where('slug', $baseSlug)->doesntExist()) {
            return $baseSlug;
        }

        // Query the maximum existing numeric suffix in a single query
        $maxSuffix = static::query()
            ->where('slug', 'LIKE', "{$baseSlug}-%")
            ->max(DB::raw('CAST(SUBSTRING_INDEX(slug, "-", -1) AS SIGNED)'));

        if ($maxSuffix === null || $maxSuffix <= 0) {
            return "{$baseSlug}-2";
        }

        return "{$baseSlug}-" . ($maxSuffix + 1);
    }
}

How It Works

1. Initial Availability Check: Checks if the clean base slug ("laravel-tips") exists. If available, it returns immediately with 1 simple indexed lookup.
2. SUBSTRING_INDEX Extraction: For duplicate titles, MySQL's SUBSTRING_INDEX(slug, "-", -1) extracts the trailing characters after the last hyphen.
3. CAST(... AS SIGNED): Converts the extracted substring into an integer so the MAX() aggregate computes the numerical maximum rather than alphabetical sorting.
4. Calculated Next Suffix: Increments the maximum found suffix (max + 1), guaranteeing uniqueness without sequential trial-and-error queries.

Performance Comparison

• While Loop Approach: Runs (N) database queries (where (N) is the number of existing collisions).
• Direct Max Calculation: Always runs exactly 2 queries regardless of whether 2 or 2,000 colliding records exist.

Summary

• Avoid while (Model::whereSlug(...)->exists()) loops that create unpredictable N+1 database roundtrips.
• Use SQL string extraction and integer casting to retrieve the maximum numerical suffix in a single lookup.
• Guarantees fast, predictable execution time during bulk imports and high-traffic record creation.