Seeders

A seeder is a class that fills tables with data: test posts for development or required records such as a list of categories. With it a database that is empty after migrations gets content in a second, so pages can be checked against it. Seeders live in the app/Database/Seeds folder.

Creating a seeder

php spark make:seeder PostSeeder

The command creates the file app/Database/Seeds/PostSeeder.php with an empty run() method. Add one record to it:

// app/Database/Seeds/PostSeeder.php
namespace App\Database\Seeds;
 
use CodeIgniter\Database\Seeder;
 
class PostSeeder extends Seeder
{
    public function run()
    {
        $this->db->table('posts')->insert([
            'title' => 'First post',
            'body' => 'The text of the first post.',
            'status' => 1,
            'created_at' => date('Y-m-d H:i:s'),
        ]);
    }
}

The $this->db property is the database connection. The table('posts') method chooses the table, insert() adds a row.

Running

php spark db:seed PostSeeder

The terminal reports that the seeder has run, and a record appears in the posts table. Every run adds the rows again — a seeder does not check whether they already exist.

Many records

Several rows are easier to build in a loop and insert with one query:

public function run()
{
    $posts = [];
 
    for ($i = 1; $i <= 20; $i++) {
        $posts[] = [
            'title' => "Post #$i",
            'body' => 'The text of the post.',
            'status' => $i % 3 === 0 ? 0 : 1,
            'created_at' => date('Y-m-d H:i:s'),
        ];
    }
 
    $this->db->table('posts')->insertBatch($posts);
}

insertBatch() takes an array of rows. The table gets twenty posts, every third one with status 0, that is a draft.

Several seeders

When there are more tables, a main seeder calls the others in the right order:

// app/Database/Seeds/DatabaseSeeder.php
namespace App\Database\Seeds;
 
use CodeIgniter\Database\Seeder;
 
class DatabaseSeeder extends Seeder
{
    public function run()
    {
        $this->call('UserSeeder');
        $this->call('PostSeeder');
    }
}

Now one command fills the whole database: php spark db:seed DatabaseSeeder.

Starting from a clean database

During development the database is often rebuilt from scratch:

php spark migrate:refresh
php spark db:seed DatabaseSeeder

The first command drops and recreates the tables, the second fills them.

Common mistake

A seeder does not clear the table: run it twice and there are twice as many records, and with unique columns the second run ends with an error. Before filling again, rebuild the tables with migrate:refresh or clear the table at the start of run() with $this->db->table('posts')->truncate(). Test seeders are never run on the live server.